Product item having coded data identifying a layout

[0001] Various methods, systems and apparatus relating to the present invention are disclosed in the following US Patents/Patent Applications filed by the applicant or assignee of the present invention:

6623101	6406129	6505916	6457809	6550895	6457812	10/296434
6428133	6746105	6750901	6476863	6788336	10/815621	10/815612
10/815630	10/815637	10/815638	10/815640	10/815642	10/815643	10/815644
10/815618	10/815639	10/815635	10/815647	10/815634	10/815632	10/815631
10/815648	10/815641	10/815645	10/815646	10/815617	10/815620	10/815615
10/815613	10/815633	10/815619	10/815616	10/815614	60/702191	10/815636
10/815649	11/041650	11/041651	11/041652	11/041649	11/041610	11/041609
11/041626	11/041627	11/041624	11/041625	11/041556	11/041580	11/041723
11/041698	11/041648	10/815609	10/815627	10/815626	10/815610	10/815611
10/815623	7070110	10/815629	HYT010US	10/815625	10/815624	10/815628
10/913375	10/913373	10/913374	10/913372	10/913377	10/913378	10/913380
10/913379	10/913376	10/913381	10/986402	11/172816	11/172815	11/172814
IRB016US	IRB017US	IRB018US	10/409876	10/409848	10/409845	11/084796
11/084742	11/084806	09/575197	09/575159	09/575123	6825945	09/575165
6813039	09/693415	6987506	6824044	09/608970	7038797	6980318
6816274	09/575139	09/575186	6681045	6678499	6679420	6963845
6976220	6728000	09/693219	09/575145	6976035	6813558	6766942
6965454	6995859	09/575192	6720985	09/609303	6922779	6978019
6847883	09/693647	09/721895	09/607843	09/693690	6959298	6973450
09/609553	6965882	09/608022	09/575181	09/722174	09/721896	10/291522
6718061	10/291523	10/291471	7012710	6825956	10/291481	10/291509
10/291825	10/291519	7031010	6972864	6862105	7009738	6989911
6982807	10/291576	6829387	6714678	6644545	6609653	6651879
10/291555	10/291510	10/291592	10/291542	7044363	7004390	6867880
7034953	6987581	10/291556	10/291821	10/291525	10/291586	10/291822
10/291524	10/291553	6850931	6865570	6847961	10/685523	10/685583
10/685455	10/685584	10/757600	10/804034	10/793933	6889896	10/831232
10/884882	6996274	10/943938	10/943874	10/943872	10/944044	10/943942
10/944043	10/949293	10/943877	6986459	10/954170	10/981773	10/981626
10/981616	10/981627	10/974730	10/986337	10/992713	11/006536	11/020256
11/020106	11/020260	11/020321	11/020319	11/026045	11/059696	11/051032
11/059674	11/107944	11/107941	11/082940	11/082815	11/082827	11/082829
6991153	6991154	11/124256	11/123136	11/154676	11/159196	11/182002
11/202251	11/202252	11/202253	11/203200	11/202218	11/206778	11/203424
11/222977	11/228450	11/227239	11/286334	11/298632	11/349143	11/442428
11/442385	7068382	7007851	6957921	6457883	10/743671	7044381
11/203205	09/928055	09/927684	09/928108	7038066	09/927809	7062651
6789194	6789191	10/900129	10/900127	10/913328	10/913350	10/982975
10/983029	11/331109	6644642	6502614	6622999	6669385	6827116
7011128	10/949307	6549935	6987573	6727996	6591884	6439706
6760119	09/575198	7064851	6826547	6290349	6428155	6785016
6831682	6741871	6927871	6980306	6965439	6840606	7036918
6977746	6970264	7068389	10/659027	10/659026	10/884885	10/884883
10/901154	10/932044	10/962412	10/962510	10/962552	10/965733	10/965933
10/974742	10/982974	10/983018	10/986375	11/107817	11/148238	11/149160
11/250465	11/327491	6982798	6870966	6822639	6474888	6627870
6724374	6788982	09/722141	6788293	6946672	6737591	09/722172
09/693514	09/721893	09/722088	6795593	6980704	6768821	10/291366
7041916	6797895	7015901	10/782894	10/782895	10/778056	10/778058
10/778060	10/778059	10/778063	10/778062	10/778061	10/778057	10/846895
10/917468	10/917467	10/917466	10/917465	10/917356	10/948169	10/948253
10/948157	10/917436	10/943856	10/919379	7019319	10/943878	10/943849
7043096	11/071267	11/144840	11/155556	11/155557	11/193481	11/193435
11/193482	11/193479	11/255941	11/281671	11/298474	7055739	09/575129
6830196	6832717	09/721862	10/473747	10/120441	6843420	10/291718
6789731	7057608	6766944	6766945	10/291715	10/291559	10/291660
10/531734	10/409864	10/309358	10/537159	10/410484	10/884884	6983878
10/786631	10/853782	10/893372	6929186	6994264	7017826	7014123
10/971051	10/971145	10/971146	7017823	7025276	10/990459	11/059684
11/074802	NPT058US	10/492169	10/492152	10/492168	10/492161	10/492154
10/502575	10/531229	10/683151	10/531733	10/683040	10/510391	10/510392
10/919261	10/778090	6957768	09/575162	09/575172	09/575170	09/575171
09/575161	6982701	6982703	10/291538	6786397	6947027	6975299
10/291714	7048178	10/291541	6839053	7015900	7010147	10/291713
6914593	10/291546	6938826	10/913340	10/940668	6992662	11/039897
11/074800	11/074782	11/074777	11/075917	11/102698	11/102843	11/202112
11/442114	6454482	6808330	6527365	6474773	6550997	10/181496
6957923	10/309185	10/949288	10/962400	10/969121	11/185722	11/181754
11/203180	09/517539	6566858	6331946	6246970	6442525	09/517384
09/505951	6374354	09/517608	6816968	6757832	6334190	6745331
09/517541	10/203559	10/203560	10/203564	10/636263	10/636283	10/866608
10/902889	10/902833	10/940653	10/942858	10/727181	10/727162	10/727163
10/727245	10/727204	10/727233	10/727280	10/727157	10/727178	10/727210
10/727257	10/727238	10/727251	10/727159	10/727180	10/727179	10/727192
10/727274	10/727164	10/727161	10/727198	10/727158	10/754536	10/754938
10/727227	10/727160	10/934720	11/212702	11/272491	PEA33US	10/296522
6795215	7070098	09/575109	6805419	6859289	6977751	6398332
6394573	6622923	6747760	6921144	10/884881	10/943941	10/949294
11/039866	11/123011	6986560	7008033	11/148237	11/248435	11/248426
PEC30US	10/922846	10/922845	10/854521	10/854522	10/854488	10/854487
10/854503	10/854504	10/854509	10/854510	10/854496	10/854497	10/854495
10/854498	10/854511	10/854512	10/854525	10/854526	10/854516	10/854508
10/854507	10/854515	10/854506	10/854505	10/854493	10/854494	10/854489
10/854490	10/854492	10/854491	10/854528	10/854523	10/854527	10/854524
10/854520	10/854514	10/854519	10/854513	10/854499	10/854501	10/854500
10/854502	10/854518	10/854517	10/934628	11/212823	10/407212	10/407207
10/683064	10/683041	10/728804	10/728952	10/728806	6991322	10/728790
10/728884	10/728970	10/728784	10/728783	10/728925	6962402	10/728803
10/728780	10/728779	10/773189	10/773204	10/773198	10/773199	6830318
10/773201	10/773191	10/773183	10/773195	10/773196	10/773186	10/773200
10/773185	10/773192	10/773197	10/773203	10/773187	10/773202	10/773188
10/773194	10/773193	10/773184	7018021	11/060751	11/060805	11/188017
11/298773	11/298774	11/329157	11/097308	11/097309	11/097335	11/097299
11/097310	11/097213	11/210687	11/097212	11/212637	MTD001US	MTD002US
6405055	6628430	10/920230	10/920372	10/920229	10/919366	10/919241
10/919242	10/919243	10/919380	10/919381	10/919382	10/919383	7075684
10/503924	10/503901	6915140	6999206	10/659023	10/659022	10/920219
6967750	6995876	10/920225	11/107942	11/107943	11/209711	10/659025
6914686	10/920221	10/920280	11/124158	11/124196	11/124199	11/124162
11/124202	11/124197	11/124154	11/124198	11/124153	11/124151	11/124160
11/124192	11/124175	11/124163	11/124149	11/124152	11/124173	11/124155
11/124157	11/124174	11/124194	11/124164	11/124200	11/124195	11/124166
11/124150	11/124172	11/124165	11/124186	11/124185	11/124184	11/124182
11/124201	11/124171	11/124181	11/124161	11/124156	11/124191	11/124159
11/124175	11/124188	11/124170	11/124187	11/124189	11/124190	11/124180
11/124193	11/124183	11/124178	11/124177	11/124148	11/124168	11/124167
11/124179	11/124169	11/187976	11/188011	11/188014	MCD062US	11/228540
11/228500	11/228501	11/228530	11/228490	11/228531	11/228504	11/228533
11/228502	11/228507	11/228482	11/228505	11/228497	11/228487	11/228529
11/228484	11/228489	11/228518	11/228536	11/228496	11/228488	11/228506
11/228516	11/228526	11/228539	11/228538	11/228524	11/228523	11/228519
11/228528	11/228527	11/228525	11/228520	11/228498	11/228511	11/228522
111/228515	11/228537	11/228534	11/228491	11/228499	11/228509	11/228492
11/228493	11/228510	11/228508	11/228512	11/228514	11/228494	11/228495
11/228486	11/228481	11/228477	11/228485	11/228483	11/228521	11/228517
11/228532	11/228513	11/228503	11/228480	11/228535	11/228478	11/228479
10/980187	11/246684	11/246672	11/246673	11/246683	11/246682	11/246687
11/246718	11/246685	11/246686	11/246703	11/246691	11/246711	11/246690
11/246712	11/246717	11/246709	11/246700	11/246701	11/246702	11/246668
11/246697	11/246698	11/246699	11/246675	11/246674	11/246667	10/760272
10/760273	10/760187	10/760182	10/760188	10/760218	10/760217	10/760216
10/760233	10/760246	10/760212	10/760243	10/760201	10/760185	10/760253
10/760255	10/760209	10/760208	10/760194	10/760238	10/760234	10/760235
10/760183	10/760189	10/760262	10/760232	10/760231	10/760200	10/760190
10/760191	10/760227	10/760207	10/760181	11/446227	11/454904	MPA36US
MPA37US	MPA38US	MPA39US	MPA40US	MPA41US	11/246676	11/246677
11/246678	11/246679	11/246680	11/246681	11/246714	11/246713	11/246689
11/246671	11/246670	11/246669	11/246704	11/246710	11/246688	11/246716
11/246715	11/246707	11/246706	11/246705	11/246708	11/246693	11/246692
11/246696	11/246695	11/246694	FNE010US	FNE011US	FNE012US	FNE013US
FNE015US	FNE016US	FNE017US	FNE018US	FNE019US	FNE020US	FNE021US
FNE022US	FNE023US	FNE024US	FNE025US	FNE026US	11/003786	11/003616
11/003418	11/003334	11/003600	11/003404	11/003419	11/003700	11/003601
11/003618	11/003615	11/003337	11/003698	11/003420	6984017	11/003699
11/071473	11/003463	11/003701	11/003683	11/003614	11/003702	11/003684
11/003619	11/003617	11/293800	11/293802	11/293801	11/293808	11/293809
CAG006US	CAG007US	CAG008US	CAG009US	CAG010US	CAG011US	11/293804
11/293840	11/293803	11/293833	11/293834	11/293835	11/293836	11/293837
11/293792	11/293794	11/293839	11/293826	11/293829	11/293830	11/293827
11/293828	11/293795	11/293823	11/293824	11/293831	11/293815	11/293819
11/293818	11/293817	11/293816	RMC001US	10/760254	10/760210	10/760202
10/760197	10/760198	10/760249	10/760263	10/760196	10/760247	10/760223
10/760264	10/760244	10/760245	10/760222	10/760248	10/760236	10/760192
10/760203	10/760204	10/760205	10/760206	10/760267	10/760270	10/760259
10/760271	10/760275	10/760274	10/760268	10/760184	10/760195	10/760186
10/760261	10/760258	11/442178	RRA35US	RRA36US	11/014764	11/014763
11/014748	11/014747	11/014761	11/014760	11/014757	11/014714	11/014713
11/014762	11/014724	11/014723	11/014756	11/014736	11/014759	11/014758
11/014725	11/014739	11/014738	11/014737	11/014726	11/014745	11/014712
11/014715	11/014751	11/014735	11/014734	11/014719	11/014750	11/014749
11/014746	11/014769	11/014729	11/014743	11/014733	11/014754	11/014755
11/014765	11/014766	11/014740	11/014720	11/014753	11/014752	11/014744
11/014741	11/014768	11/014767	11/014718	11/014717	11/014716	11/014732
11/014742	11/097268	11/097185	11/097184	11/293820	11/293813	11/293822
11/293812	11/293821	11/293814	11/293793	11/293842	11/293811	11/293807
11/293806	11/293805	11/293810	PFA001US

[0002] The above applications have been identified by their filing docket number, which will be substituted with the corresponding application number, once assigned.

[0003] The present invention broadly relates to a method and apparatus for the identification and protection of products and security documents using machine readable tags disposed on or in a surface of the product or security document, and user interaction therewith.

[0004] The following applications have been filed by the Applicant simultaneously with the present application: HYG020US HYG021US HYG022US HYG023US HYG024US HYG025US

[0005] The disclosures of these co-pending applications are incorporated herein by reference. The above applications have been identified by their filing docket number, which will be substituted with the corresponding application number, once assigned.

Surface Coding Background

[0006] The netpage surface coding consists of a dense planar tiling of tags. Each tag encodes its own location in the plane. Each tag also encodes, in conjunction with adjacent tags, an identifier of the region containing the tag. This region ID is unique among all regions. In the netpage system the region typically corresponds to the entire extent of the tagged surface, such as one side of a sheet of paper.

[0007] The surface coding is designed so that an acquisition field of view large enough to guarantee acquisition of an entire tag is large enough to guarantee acquisition of the ID of the region containing the tag. Acquisition of the tag itself guarantees acquisition of the tag's two-dimensional position within the region, as well as other tag-specific data. The surface coding therefore allows a sensing device to acquire a region ID and a tag position during a purely local interaction with a coded surface, e.g. during a “click” or tap on a coded surface with a pen.

[0008] The use of netpage surface coding is described in more detail in the following copending patent applications, U.S. Ser. No. 10/815,647 (docket number HYG001US), entitled “Obtaining Product Assistance” filed on 2^nd Apr. 2004; and U.S. Ser. No. 10/815,609 (docket number HYT001US), entitled “Laser Scanner Device for Printed Product Identification Cod” filed on 2^nd Apr. 2004.

Cryptography Background

[0009] Cryptography is used to protect sensitive information, both in storage and in transit, and to authenticate parties to a transaction. There are two classes of cryptography in widespread use: secret-key cryptography and public-key cryptography.

[0010] Secret-key cryptography, also referred to as symmetric cryptography, uses the same key to encrypt and decrypt a message. Two parties wishing to exchange messages must first arrange to securely exchange the secret key.

[0011] Public-key cryptography, also referred to as asymmetric cryptography, uses two encryption keys. The two keys are mathematically related in such a way that any message encrypted using one key can only be decrypted using the other key. One of these keys is then published, while the other is kept private. They are referred to as the public and private key respectively. The public key is used to encrypt any message intended for the holder of the private key. Once encrypted using the public key, a message can only be decrypted using the private key. Thus two parties can securely exchange messages without first having to exchange a secret key. To ensure that the private key is secure, it is normal for the holder of the private key to generate the public-private key pair.

[0012] Public-key cryptography can be used to create a digital signature. If the holder of the private key creates a known hash of a message and then encrypts the hash using the private key, then anyone can verify that the encrypted hash constitutes the “signature” of the holder of the private key with respect to that particular message, simply by decrypting the encrypted hash using the public key and verifying the hash against the message. If the signature is appended to the message, then the recipient of the message can verify both that the message is genuine and that it has not been altered in transit.

[0013] Secret-key can also be used to create a digital signature, but has the disadvantage that signature verification can also be performed by a party privy to the secret key.

[0014] To make public-key cryptography work, there has to be a way to distribute public keys which prevents impersonation. This is normally done using certificates and certificate authorities. A certificate authority is a trusted third party which authenticates the association between a public key and a person's or other entity's identity. The certificate authority verifies the identity by examining identity documents etc., and then creates and signs a digital certificate containing the identity details and public key. Anyone who trusts the certificate authority can use the public key in the certificate with a high degree of certainty that it is genuine. They just have to verify that the certificate has indeed been signed by the certificate authority, whose public key is well-known.

[0015] To achieve comparable security to secret-key cryptography, public-key cryptography utilises key lengths an order of magnitude larger, i.e. a few thousand bits compared with a few hundred bits.

[0016] Schneier B. (Applied Cryptography, Second Edition, John Wiley & Sons 1996) provides a detailed discussion of cryptographic techniques.

[0017] In a first aspect the present invention provides an object comprising first coded data disposed on or in a surface thereof, said first coded data identifying a plurality of locations on the surface and a layout of at least one interactive element associated with the surface.

[0018] In a further aspect the object further comprises graphical information printed on the surface, said graphical information relating to the at least one interactive element.

[0019] Optionally the layout is identified by a layout number, and one layout number is associated with a plurality of objects.

[0020] In a further aspect there is provided an object which is a consumer product item.

[0021] Optionally, the first coded data further identifies a class of product.

[0022] Optionally, the class of product is identified by a product class number and/or a manufacturer number.

[0023] Optionally, the class of product is identified by a Universal Product Code (UPC).

[0024] Optionally, the surface is defined by a label, packaging or the product item itself.

[0025] Optionally, the first coded data further identifies a flag for distinguishing the first coded data from other types of coded data.

[0026] In a further aspect there is provided an object further comprising a unique identifier for uniquely identifying the object, said unique identifier being distinguishable from the first coded data and independently readable.

[0027] Optionally, the unique identifier identifies a serial number.

[0028] Optionally, the unique identifier identifies an Electronic Product Code (EPC).

[0029] Optionally, the unique identifier comprises second coded data disposed on or in a surface of the object, said second coded data identifying a unique identity for the object.

[0030] Optionally, the second coded data further identifies a digital signature for the unique identity.

[0031] Optionally, the first coded data identifies a flag for distinguishing the first coded data from the second coded data.

[0032] Optionally, the unique identifier comprises a random pattern disposed on or in a surface of the object, said random pattern defining at least one fingerprint for the object.

[0033] Optionally, the random pattern is defined by a taggant randomly dispersed in ink printed on the surface.

[0034] Optionally, the unique identifier is contained in an RFID tag.

[0035] Optionally, the first coded data is defined by a plurality of tags, each tag identifying its own location on the surface and the layout of the at least one interactive element associated with the surface.

[0036] Optionally, each tag further identifies a class of product and/or a flag for distinguishing the first coded data from other types of coded data.

[0037] In another aspect the present invention provides data reader for interacting with an object, said object comprising first coded data disposed on or in a surface thereof, said first coded data identifying a plurality of locations on the surface and a layout of at least one interactive element associated with the surface,

said data reader comprising:

• • [0038] an optical sensor for sensing at least some of the first coded data;
  • [0039] a processor for generating layout data using the sensed coded data, said layout data identifying a position of the data reader relative to the surface and a layout of the at least one interactive element; and
  • [0040] means for communicating the layout data to a computer system.

[0041] In another aspect the present invention provides data reader for interacting with an object, said object comprising coded data disposed on or in a surface thereof, said coded data identifying: a plurality of locations on the surface and either (i) a layout of at least one interactive element associated with the surface, or (ii) a unique identity of the object,

said data reader comprising:

• • [0042] an optical sensor for sensing at least some of the coded data;
  • [0043] a processor configured for:
    • [0044] determining whether the sensed coded data identifies (i) the layout or (ii) the unique identity;
    • [0045] generating layout data using the sensed coded data, said layout data identifying a position of the data reader relative to the surface and either (i) the layout of the at least one interactive element or (ii) the unique identity; and
  • [0046] means for communicating the layout data to a computer system.

[0047] Optionally the processor determines whether the sensed coded data identifies (i) the layout or (ii) the unique identity, based on the presence of a flag in the sensed coded data.

[0048] In a further aspect there is provided a data reader which is selected from any one of the group comprising: a fixed scanner; a handheld scanner; a mobile phone; a pen; a stylus; and a personal digital assistant.

[0049] In another aspect the present invention provides a system for interacting with an object, said system comprising:

• • [0050] an object comprising first coded data disposed on or in a surface thereof, said first coded data identifying: a plurality of locations on the surface and a layout of at least one interactive element associated with the surface; and
  • [0051] a data reader comprising:
    • [0052] an optical sensor for sensing at least some of the first coded data;
    • [0053] a processor for generating layout data using the sensed coded data, said layout data identifying a position of the data reader relative to the surface and a layout of the at least one interactive element; and
    • [0054] means for communicating the layout data to a computer system.

[0055] In another aspect the present invention provides a system for identifying an interaction with an object, said object comprising first coded data disposed on or in a surface thereof, said first coded data identifying: a plurality of locations on the surface and a layout of at least one interactive element associated with the surface,

said system comprising a computer system configured for:

• • [0056] receiving layout data from a data reader interacting with the surface, said layout data identifying a position of the data reader relative to the surface and a layout of the at least one interactive element;
  • [0057] identifying in the computer system, using the layout data, an interaction with the object.

[0058] Optionally, the computer system is configured for:

• • [0059] retrieving the layout identified by the first coded data using the layout data; and
  • [0060] identifying the interaction by interpreting the position of the reader with reference to a zone of the at least one interactive element as specified in the retrieved layout.

[0061] In another aspect the present invention provides a method of interacting with an object, said object comprising first coded data disposed on or in a surface thereof, said first coded data identifying: a plurality of locations on the surface and a layout of at least one interactive element associated with the surface,

said method comprising the steps of:

• • [0062] sensing at least some of the first coded data;
  • [0063] generating layout data using the sensed coded data, said layout data identifying a position of the data reader relative to the surface and a layout of the at least one interactive element; and
  • [0064] communicating the layout data to a computer system.

[0065] In another aspect the present invention provides a method of identifying an interaction with an object, said object comprising first coded data disposed on or in a surface thereof, said first coded data identifying: a plurality of locations on the surface and a layout of at least one interactive element associated with the surface,

said method comprising the steps of:

• • [0066] receiving, in a computer system, layout data from a data reader interacting with the surface, said layout data identifying a position of the data reader relative to the surface and a layout of the at least one interactive element;
  • [0067] identifying in the computer system, using the layout data, an interaction with the object.

[0068] Optionally, said identifying step comprises:

• • [0069] retrieving the layout identified by the first coded data using the layout data; and
  • [0070] identifying the interaction by interpreting the position of the reader with reference to a zone of the at least one interactive element as specified in the retrieved layout.

[0071] In a second aspect the present invention provides an object comprising first coded data disposed on or in a surface thereof and an identifier, said first coded data identifying a plurality of locations on the surface and said identifier identifying a unique identity of the object,

wherein the first coded data and the identifier are distinguishable from each other and independently readable.

[0072] Optionally, the identifier identifies a serial number.

[0073] Optionally, the identifier identifies an Electronic Product Code (EPC).

[0074] Optionally, the identifier further identifies a digital signature for the unique identity.

[0075] Optionally, the identifier comprises second data disposed on or in a surface of the object.

[0076] Optionally, the first and second coded data are disposed on the same surface of the object.

[0077] Optionally, the second coded data comprises a barcode.

[0078] Optionally, the barcode is a linear barcode or a two-dimensional barcode.

[0079] Optionally, the first coded data is printed with a first ink and the second coded data is printed with a second ink, wherein the first and second inks may be the same or different from each other.

[0080] Optionally, the first ink is substantially invisible to the unaided human eye and the second ink is visible to the unaided human eye.

[0081] Optionally, at least a portion of the first coded data is coincident with the second coded data.

[0082] Optionally, the first coded data further identifies a flag for distinguishing the first coded data from the second coded data.

[0083] Optionally, the first coded data further identifies a layout of at least one interactive element associated with the surface.

[0084] Optionally, the layout is identified by a layout number, and one layout number is associated with a plurality of objects

[0085] Optionally, the object is a consumer product item and the first coded data further identifies a product class.

[0086] Optionally, the product class is identified by a product class number and/or a manufacturer number.

[0087] Optionally, the product class is identified by a Universal Product Code (UPC).

[0088] Optionally, the first coded data further identifies the unique identity of the object.

[0089] Optionally, the identifier comprises an RFID tag.

[0090] Optionally, the identifier comprises a random pattern disposed on or in a surface of the object, said random pattern defining at least one fingerprint for the object.

[0091] Optionally, the random pattern is defined by a taggant randomly dispersed in ink printed on the surface.

[0092] In a third aspect the present invention provides an object comprising first coded data disposed on or in a surface thereof and an RFID tag, said first coded data identifying a plurality of locations on the surface and said RFID tag identifying a unique identity of the object.

[0093] Optionally, the RFID tag identifies a serial number.

[0094] Optionally, the RFID tag identifies an Electronic Product Code (EPC).

[0095] Optionally, the RFID tag further identifies a digital signature for the unique identity.

[0096] Optionally, the digital signature is a public key signature.

[0097] Optionally, the digital signature is a random signature.

[0098] Optionally, the digital signature is a secret-key digital signature.

[0099] Optionally, the RFID tag is disposed on a same or different surface of the object relative to the coded data.

[0100] Optionally, the first coded data further identifies a layout of at least one interactive element associated with the surface.

[0101] Optionally, the RFID tag further identifies a layout of at least one interactive element associated with the surface.

[0102] Optionally, the layout is identified by a layout number, and one layout number is associated with a plurality of objects

[0103] Optionally, the object is a consumer product item and the first coded data further identifies a product class.

[0104] Optionally, the product class is identified by a product class number and/or a manufacturer number.

[0105] Optionally, the product class is identified by a Universal Product Code (UPC).

[0106] Optionally, the first coded data further identifies the unique identity of the object.

[0107] In a further aspect there is provided a data reader for interacting with an object, said object comprising first coded data disposed on or in a surface thereof and an RFID tag, said first coded data identifying a plurality of locations on the surface and said RFID tag identifying a unique identity of the object,

said data reader comprising:

• • [0108] an optical sensor for sensing at least some of the first coded data;
  • [0109] an RFID transceiver for sensing the RFID tag;
  • [0110] a processor for generating indicating data using the sensed coded data and the sensed RFID tag, said indicating data identifying a position of the data reader relative to the surface and a unique identity of the object; and
  • [0111] means for communicating the indicating data to a computer system.

[0112] In another aspect there is provided a data reader which is selected from any one of the group comprising: a fixed scanner; a handheld scanner; a mobile phone; a pen; a stylus; and a personal digital assistant.

[0113] In another aspect the present invention provides a system for interacting with an object, said system comprising:

• • [0114] an object comprising first coded data disposed on or in a surface thereof and an RFID tag, said first coded data identifying a plurality of locations on the surface and said RFID tag identifying a unique identity of the object; and
  • [0115] a data reader comprising:
    • [0116] an optical sensor for sensing at least some of the first coded data;
    • [0117] an RFID transceiver for sensing the RFID tag;
    • [0118] a processor for generating indicating data using the sensed coded data and the sensed RFID tag, said indicating data identifying a position of the data reader relative to the surface and a unique identity of the object; and
    • [0119] means for communicating the indicating data to a computer system.

[0120] In a further aspect the present invention provides a method of interacting with an object, said object comprising first coded data disposed on or in a surface thereof and an RFID tag, said first coded data identifying a plurality of locations on the surface and said RFID tag identifying a unique identity of the object,

said method comprising the steps of:

• • [0121] sensing at least some of the first coded data;
  • [0122] sensing the RFID tag;
  • [0123] generating indicating data using the sensed coded data and sensed RFID tag, said indicating data identifying a position of the data reader relative to the surface and a unique identity of the object; and
  • [0124] communicating the indicating data to a computer system.

[0125] In a fourth aspect the present invention provides an object comprising first coded data and a random pattern disposed on or in a surface thereof, said first coded data identifying a plurality of fiducials on the surface and said random pattern defining at least one fingerprint for the object.

[0126] Optionally, the or each fingerprint identifies an object identity.

[0127] Optionally, the or each fingerprint identifies a serial number.

[0128] Optionally, the or each fingerprint identifies an Electronic Product Code (EPC).

[0129] Optionally, the random pattern is defined by a taggant randomly dispersed in ink printed on the surface.

[0130] Optionally, the fiducials are all distinct from each other.

[0131] Optionally, each fiducial identifies a unique location on the surface.

[0132] Optionally, the first coded data further identifies a layout of at least one interactive element associated with the surface.

[0133] Optionally, the layout is identified by a layout number, and one layout number is associated with a plurality of objects

[0134] Optionally, the object is a consumer product item and the first coded data further identifies a product class.

[0135] Optionally, the product class is identified by a product class number and/or a manufacturer number.

[0136] Optionally, the product class is identified by a Universal Product Code (UPC).

[0137] Optionally, the first coded data further identifies a unique identity of the object.

[0138] In a further aspect the present invention provides a data reader for interacting with an object, said object comprising first coded data and a random pattern disposed on or in a surface thereof, said first coded data identifying a plurality of fiducials on the surface and said random pattern defining at least one fingerprint for the object,

said data reader comprising:

• • [0139] a first optical sensor for sensing at least some of the first coded data;
  • [0140] a second optical sensor for sensing at least some of the random pattern;
  • [0141] a processor configured for generating fingerprint data using the sensed coded data and the sensed random pattern, said fingerprint data identifying at least some of the random pattern and at least one fiducial; and
  • [0142] communication means configured for communicating the fingerprint data to a computer system.

[0143] Optionally, the first and second optical sensors are the same optical sensor or different optical sensors.

[0144] In another aspect the present invention provides a data reader which is selected from any one of the group comprising: a fixed scanner; a handheld scanner; a mobile phone; a pen; a stylus; and a personal digital assistant.

[0145] In another aspect the present invention provides a system for interacting with an object, said system comprising:

• • [0146] an object comprising first coded data and a random pattern disposed on or in a surface thereof, said first coded data identifying a plurality of fiducials on the surface and said random pattern defining at least one fingerprint for the object; and
  • [0147] a data reader comprising:
    • [0148] a first optical sensor for sensing at least some of the first coded data;
    • [0149] a second optical sensor for sensing at least some of the random pattern;
    • [0150] a processor configured for generating fingerprint data using the sensed coded data and the sensed random pattern, said fingerprint data identifying at least some of the random pattern and at least one fiducial; and
    • [0151] communication means configured for communicating the fingerprint data to a computer system.

[0152] In another aspect the present invention provides a system for identifying an object, said object comprising first coded data and a random pattern disposed on or in a surface thereof, said first coded data identifying a plurality of fiducials on the surface and said random pattern defining at least one fingerprint for the object, said system comprising a computer system configured for:

[0153] receiving fingerprint data from a data reader interacting with the surface, said fingerprint data identifying at least some of the random pattern and at least one fiducial; and

[0154] identifying in the computer system, using the fingerprint data, an object identity.

[0155] In another aspect the present invention provides a system for authenticating an object, said object comprising first coded data and a random pattern disposed on or in a surface thereof, said first coded data identifying a plurality of fiducials on the surface and said random pattern defining at least one fingerprint for the object,

said system comprising a computer system configured for:

• • [0156] receiving fingerprint data from a data reader interacting with the surface, said fingerprint data identifying at least some of the random pattern and at least one fiducial;
  • [0157] identifying, using the fingerprint data, an object identity; and
  • [0158] authenticating the object using the object identity.

[0159] Optionally, the computer system is configured for:

• • [0160] identifying a reference fingerprint using the fingerprint data; and
  • [0161] retrieving an object identity corresponding to the reference fingerprint identified.

[0162] Optionally, the reference fingerprint comprises a plurality of random marks positioned relative to at least one fiducial.

[0163] Optionally, the first coded data further identifies a product class, and the computer system is configured for:

• • [0164] receiving indicating data from the data reader, said indicating data identifying the product class;
  • [0165] identifying, using the fingerprint data and the indicating data, the object identity.

[0166] In another aspect the present invention provides a method of recording at least one reference fingerprint for an object, said object having a unique object identity and comprising first coded data and a random pattern disposed on or in a surface thereof, said first coded data identifying a plurality of fiducials on the surface,

said method comprising the steps of:

• • [0167] sensing and recording the first coded data and the random pattern;
  • [0168] determining at least one reference fingerprint for the object, the or each reference fingerprint comprising at least a portion of the recorded random pattern and at least one fiducial corresponding to said portion;
  • [0169] associating the object identity with the or each reference fingerprint.

[0170] In another aspect the present invention provides a method of interacting with an object, said object comprising first coded data and a random pattern disposed on or in a surface thereof, said first coded data identifying a plurality of fiducials on the surface and said random pattern defining at least one fingerprint for the object,

said method comprising the steps of:

• • [0171] sensing at least some of the first coded data;
  • [0172] sensing at least some of the random pattern;
  • [0173] generating fingerprint data using the sensed coded data and the sensed random pattern, said fingerprint data identifying at least some of the random pattern and at least one fiducial; and
  • [0174] communicating the fingerprint data to a computer system.

[0175] In another aspect the present invention provides a method of identifying an object, said object comprising first coded data and a random pattern disposed on or in a surface thereof, said first coded data identifying a plurality of fiducials on the surface and said random pattern defining at least one fingerprint for the object,

said method comprising the steps of:

• • [0176] receiving, in a computer system, fingerprint data from a data reader interacting with the surface, said fingerprint data identifying at least some of the random pattern and at least one fiducial; and
  • [0177] identifying in the computer system, using the fingerprint data, an object identity.

[0178] In another aspect the present invention provides a method of authenticating an object, said object comprising first coded data and a random pattern disposed on or in a surface thereof, said first coded data identifying a plurality of fiducials on the surface and said random pattern defining at least one fingerprint for the object,

said method comprising the steps of:

• • [0179] receiving, in a computer system, fingerprint data from a data reader interacting with the surface, said fingerprint data identifying at least some of the random pattern and at least one fiducial;
  • [0180] identifying in the computer system, using the fingerprint data, an object identity; and
  • [0181] authenticating the object using the object identity.

[0182] In a fifth aspect the present invention provides a method of authenticating an object comprising an identifier, said method comprising the steps of:

• • [0183] reading the identifier using a data reader to generate identity data;
  • [0184] sending an authentication request from the data reader to a computer system, said request comprising the identity data;
  • [0185] receiving, in the data reader, an authentication message from the computer system, said authentication message comprising an indication of authenticity, a description of an object associated with the identity data and a digital signature of the authentication message;
  • [0186] verifying the digital signature; and
  • [0187] conveying the description of the object to a user if the signature is valid.

[0188] Optionally, the identifier comprises or is contained in any one of: coded data disposed in or on a surface of the object; an RFID tag; a linear barcode; a 2D barcode.

[0189] Optionally, the identifier comprises one of a plurality of tags disposed on or in a surface of the object, each tag containing coded data identifying the object identity.

[0190] Optionally, each tag identifies its own location on the surface.

[0191] Optionally, the digital signature is a public-key signature.

[0192] Optionally, the public-key signature was generated using a private key associated with the manufacturer of the object.

[0193] Optionally, the signature is verified using a public key associated with the private key.

[0194] Optionally, the data reader obtains the public key from a certificate.

[0195] Optionally, the certificate is associated with the manufacturer or a certificate authority.

[0196] Optionally, the authentication message identifies the manufacturer.

[0197] Optionally, the data reader verifies the certificate.

[0198] Optionally, the certificate includes a description of the manufacturer.

[0199] Optionally, the data reader conveys the description of the manufacturer to the user.

[0200] Optionally, the description of the object comprises at least one of:

• • [0201] an identity of the object;
  • [0202] a name or description of a manufacturer of the object;
  • [0203] a manufacturing date/time of the object;
  • [0204] a selling date/time of the object;
  • [0205] a sold status of the object;
  • [0206] a purchased status of the object; and
  • [0207] a pedigree of the object.

[0208] Optionally, the description of the object is conveyed to the user visually on a display or audibly.

[0209] Optionally, the authentication request comprises a nonce generated by the data reader.

[0210] Optionally, the authentication message comprises the nonce.

[0211] In another aspect the present invention provides a method of authenticating an object comprising an identifier, said method comprising the steps of:

• • [0212] receiving, in a computer system, an authentication request from a data reader, said request comprising identity data generated by reading the identifier;
  • [0213] sending, to the data reader, an authentication message from the computer system, said authentication message comprising an indication of authenticity, a description of an object associated with the identity data and a digital signature of the authentication message,
    thereby allowing the data reader to verify the digital signature and convey the description of the object to a user if the signature is valid.

[0214] In another aspect the present invention provides a data reader for authenticating an object comprising an identifier, said data reader being configured for:

• • [0215] reading the identifier to generate identity data;
  • [0216] sending an authentication request from the data reader to a computer system, said request comprising the identity data;
  • [0217] receiving an authentication message from the computer system, said authentication message comprising an indication of authenticity, a description of an object associated with the identity data and a digital signature of the authentication message;
  • [0218] verifying the digital signature; and
  • [0219] conveying the description of the object to a user if the signature is valid.

[0220] In another aspect the present invention provides a data reader which is a mobile phone.

[0221] In another aspect the present application provides a system for authenticating an object, said system comprising an object comprising an identifier and a data reader configured for:

• • [0222] reading the identifier to generate identity data;
  • [0223] sending an authentication request from the data reader to a computer system, said request comprising the identity data;
  • [0224] receiving an authentication message from the computer system, said authentication message comprising an indication of authenticity, a description of an object associated with the identity data and a digital signature of the authentication message;
  • [0225] verifying the digital signature; and
  • [0226] conveying the description of the object to a user if the signature is valid.

[0227] In another aspect the present application provides a system for authenticating an object comprising an identifier, said system comprising a computer system configured for:

• • [0228] receiving an authentication request from a data reader, said request comprising identity data generated by reading the identifier;
  • [0229] sending, to the data reader, an authentication message, said authentication message comprising an indication of authenticity, a description of an object associated with the identity data and a digital signature of the authentication message,
    thereby allowing the data reader to verify the digital signature and convey the description of the object to a user if the signature is valid.

[0230] In a sixth aspect the present invention provides an object comprising:

• • [0231] a first identifier identifying a unique object identity;
  • [0232] a second identifier identifying a first digital signature for the identity; and
  • [0233] a mask for masking at least one of the first identifier and the second identifier,
    wherein the at least one masked identifier is readable only when said mask has been removed.

[0234] Optionally, only the first identifier is masked.

[0235] Optionally, only the second identifier is masked.

[0236] Optionally, both the first and second identifiers are masked.

[0237] Optionally, removal of said mask provides a visual indication of tampering to a user.

[0238] Optionally, the mask is a scratch-off layer.

[0239] Optionally, the object is packaged, the mask being provided by packaging for the object.

[0240] Optionally, the at least one masked identifier comprises coded data disposed on or in a surface of the object.

[0241] Optionally, the coded data is contained in a linear barcode, a 2D barcode or a plurality of printed tags.

[0242] Optionally, the mask is opaque.

[0243] Optionally, the coded data is disposed on an inside surface of packaging for the object.

[0244] Optionally, the at least one masked identifier comprises an RFID tag.

[0245] Optionally, the mask is radiopaque.

[0246] Optionally, the first digital signature is selected from any one of: a public-key digital signature; a secret-key digital signature; and a random number.

[0247] In a further aspect the object further comprises a third identifier for use in supply chain events.

[0248] Optionally, said third identifier identifies a second digital signature for the identity.

[0249] Optionally, the first and second digital signatures are different.

[0250] Optionally, said third identifier further identifies the unique identity of the object.

[0251] Optionally, the first identifier identifies an Electronic Product Code (EPC).

[0252] In a further aspect the present invention provides a method of registering a scan event for an object with a computer system, said object comprising a first identifier identifying a unique object identity, a second identifier identifying a first digital signature for the identity and a mask for masking at least one of the first identifier and the second identifier,

said method comprising the steps of:

• • [0253] removing the mask;
  • [0254] reading the first and second identifiers;
  • [0255] generating registration data identifying the object identity and the first digital signature; and
  • [0256] sending the registration data to the computer system.

[0257] Optionally, the scan event is used to register the object as purchased.

[0258] Optionally, the registration data further identifies a purchaser identity.

[0259] Optionally, purchaser identity data is contained in a data reader used to read the identifier.

[0260] In a further aspect the present invention provides a method of authenticating an object comprising an identifier and a mask for the identifier, said method comprising the steps of:

• • [0261] removing the mask;
  • [0262] reading the identifier using a data reader to generate identity data;
  • [0263] sending an authentication request from the data reader to a computer system, said request comprising the identity data;
  • [0264] receiving, in the data reader, an authentication message from the computer system, said authentication message comprising an indication of authenticity; and
  • [0265] conveying the indicated authenticity to a user.

[0266] Optionally, the authentication message comprises a description of an object associated with the identity data and a digital signature, said method comprising the further steps of:

• • [0267] verifying the digital signature; and
  • [0268] conveying the description of the object to a user if the signature is valid.

[0269] In a seventh aspect the present invention provides a method of transacting objects, each object comprising an identifier identifying an object identity,

said method comprising, in a computer system, the steps of:

• • [0270] receiving transaction data from a data reader, said transaction data identifying the object identity;
  • [0271] identifying a transaction history for the object identity;
  • [0272] determining whether the object identity has been transacted in a previous transaction; and either:
  • [0273] (i) allowing the transaction and updating the transaction history in the event that the object identity has not been previously transacted, or
  • [0274] (ii) sending transaction history data to the data reader in the event that the object identity has been previously transacted.

[0275] Optionally, the transaction history data identifies at least one previous transaction of the object identity.

[0276] Optionally, the transaction history data enables a user to conclude that the object is second-hand or the identifier is a duplicate.

[0277] Optionally, the transaction history data identifies when the previous transaction was made.

[0278] Optionally, the transaction history data identifies where the previous transaction was made.

[0279] Optionally, the transaction history data identifies a data reader used for recording the previous transaction.

[0280] Optionally, the transaction history data identifies a user to whom ownership of the object identity is recorded.

[0281] Optionally, recordal of ownership is allowable only once in the transaction history for each object identity.

[0282] Optionally, recordal of ownership is allowable only after an initial purchasing transaction in the transaction history.

[0283] Optionally, the object comprises an interactive element specifically for recording ownership.

[0284] Optionally, the interactive element is masked by a tamper-proof mechanism.

[0285] Optionally, the transaction data identifies a user identity, said user identity being contained in the data reader.

[0286] Optionally, the transaction history records ownership of the object identity with the user identity, in the event that the object identity has not been previously transacted

[0287] Optionally, the identifier comprises or is contained in any one of: coded data disposed in or on a surface of the object; an RFID tag; a linear barcode; a 2D barcode.

[0288] Optionally, the identifier comprises one of a plurality of tags disposed on or in a surface of the object, each tag containing coded data identifying the object identity.

[0289] Optionally, each tag identifies its own location on the surface.

[0290] Optionally, the identifier identifies a serial number and/or an Electronic Product Code (EPC).

[0291] Optionally, the identifier further identifies a digital signature for the object identity, and the transaction data identifies the digital signature.

[0292] In a further aspect there is provided a system for transacting objects, each object comprising an identifier identifying an object identity,

said system comprising a computer system configured for:

• • [0293] receiving transaction data from a data reader, said transaction data identifying the object identity;
  • [0294] identifying a transaction history for the object identity;
  • [0295] determining whether the object identity has been transacted in a previous transaction; and either:
  • [0296] (i) allowing the transaction and updating the transaction history in the event that the object identity has not been previously transacted, or
  • [0297] (ii) sending transaction history data to the data reader in the event that the object identity has been previously transacted.

[0298] An example of the present invention will now be described with reference to the accompanying drawings, in which:

[0299] FIG. 1 is an example of a document including Hyperlabel encoding;

[0300] FIG. 2 is an example of a system for interacting with the Hyperlabel document of FIG. 1;

[0301] FIG. 3 is a further example of system for interacting with the Hyperlabel document of FIG. 1;

[0302] FIG. 4. is a first example of a tag structure;

[0303] FIG. 5. is an example of a symbol unit cell for the tag structure of FIG. 4;

[0304] FIG. 6. is an example of an array of the symbol unit cells of FIG. 5;

[0305] FIG. 7. is an example of symbol bit ordering in the unit cells of FIG. 5;

[0306] FIG. 8. is an example of the tag structure of FIG. 4 with every bit set;

[0307] FIG. 9. is an example of tag types within a tag group for the tag structure of FIG. 4;

[0308] FIG. 10. is an example of continuous tiling of the tag groups of FIG. 9;

[0309] FIG. 11 is an example of interleaved codewords for the tag structure of FIG. 4;

[0310] FIG. 12 is an example of a code word for the tag structure of FIG. 4;

[0311] FIG. 13. is an example of a tag and its eight immediate neighbours, each labelled with its corresponding bit index in the active area map;

[0312] FIG. 14. is an alternative example of tag types within a tag group for the tag structure of FIG. 4;

[0313] FIG. 15. is an example of continuous tiling of the tag groups of FIG. 14;

[0314] FIG. 16. is an example of the orientation-indicating cyclic position codeword R for the tag group of FIG. 14;

[0315] FIG. 17. is an example of a local codeword A for the tag group of FIG. 14;

[0316] FIG. 18. is an example of distributed codewords B, C, D and E, for the tag group of FIG. 14;

[0317] FIG. 19. is an example of a layout of complete tag group;

[0318] FIG. 20. is an example of a code word for the tag group of FIG. 14;

[0319] FIG. 21. is a second example of a tag structure;

[0320] FIG. 22. is an example of a symbol unit cell for the tag structure of FIG. 21;

[0321] FIG. 23. is an example of an array of the symbol unit cells of FIG. 22;

[0322] FIG. 24. is an example of symbol bit ordering in the unit cells of FIG. 22;

[0323] FIG. 25. is an example of the tag structure of FIG. 21 with every bit set;

[0324] FIG. 26. is an example of tag types within a tag group for the tag structure of FIG. 21;

[0325] FIG. 27. is an example of continuous tiling of the tag groups of FIG. 26;

[0326] FIG. 28 is an example of an orientation indicating cyclic position codeword for the tag structure of FIG. 21;

[0327] FIG. 29 is an example of a codeword for the tag structure of FIG. 21;

[0328] FIG. 30 is an example of fragments of distributed codewords for the tag structure of FIG. 21;

[0329] FIG. 31. is an example of continuous tiling of the tag groups of FIG. 21;

[0330] FIG. 32. is an example of a tag segment of the tag groups of FIG. 21;

[0331] FIG. 33. is an example of inter-segment spacing for the tag groups of FIG. 21;

[0332] FIG. 34. is an example of the effect of inter-segment spacing on target position for the tag groups of FIG. 21;

[0333] FIG. 35. is an example of a code word for the tag group of FIG. 21;

[0334] FIG. 36. is an example of tag coordinates for the tag group of FIG. 21;

[0335] FIG. 37. is an example of tag and six immediate neighbour tags each labelled with its corresponding bit index in the active area map;

[0336] FIG. 38. is an example of a contiguous set of tags making up a data block;

[0337] FIG. 39. is an example of an expanded tag structure;

[0338] FIG. 40 is an example of a codeword for the tag structure of FIG. 39;

[0339] FIG. 41 is an example of fragments of distributed codewords for the tag structure of FIG. 39;

[0340] FIG. 42 is a second example of fragments of distributed codewords for the tag structure of FIG. 39;

[0341] FIG. 43 is an example of an item signature object model;

[0342] FIG. 44. is an example of Scanning at Retailer interactions;

[0343] FIG. 45. is an example of Online Scanning interaction detail;

[0344] FIG. 46. is an example of Offline Scanning interaction details;

[0345] FIG. 47. is an example of netpage Pen Scanning interactions;

[0346] FIG. 48. is an example of netpage Pen Scanning interaction details;

[0347] FIG. 49. is an example of a Hyperlabel tag class diagram;

[0348] FIG. 50. is an example of an item ID class diagram;

[0349] FIG. 51. is an example of a note ID class diagram;

[0350] FIG. 52. is an example of a pharmaceutical ID class diagram;

[0351] FIG. 53. is an example of an Object Description, ownership and aggregation class diagram;

[0352] FIG. 54. is an example of an Object Scanning History class diagram;

[0353] FIG. 55. is an example of scanner class diagram;

[0354] FIG. 56. is an example of an object ID hot list diagram;

[0355] FIG. 57. is an example of a valid ID range class diagram;

[0356] FIG. 58. is an example of Public Key List class diagram;

[0357] FIG. 59. is an example of a Trusted Authenticator class diagram;

[0358] FIG. 60. is an example of Tagging and Tracking Object Management;

[0359] FIG. 61. is an example of a layout ID class diagram;

[0360] FIG. 62. is an alternative example of Hyperlabel tag class diagram;

[0361] FIG. 63. is an example of a basic product item authentication interaction diagram;

[0362] FIG. 64. is an example of a more secure product item authentication interaction diagram;

[0363] FIG. 65. is an example of mobile phone displaying a product item authentication message; and

[0364] FIG. 66. is an example of a secure scan event interaction diagram.

[0365] FIG. 67 shows a consumer product item with Hyperlabel tags and an RFID tag;

[0366] FIG. 68 shows a consumer product item with Hyperlabel tags and a separate barcode identifier;

[0367] FIG. 69 shows a consumer product item with Hyperlabel tags and graphic data containing a randomly distributed taggant overprinted on the Hyperlabel tags; and

[0368] FIG. 70 shows a consumer product item with an object identifier code and a digital signature code having a mask layer partially scratched off.

[0369] The netpage surface coding consists of a dense planar tiling of tags. Each tag encodes its own location in the plane. Each tag also encodes, in conjunction with adjacent tags, an identifier of the region containing the tag. In the netpage system, the region typically corresponds to the entire extent of the tagged surface, such as one side of a sheet of paper.

[0370] Hyperlabel is the adaptation of the netpage tags for use in unique item identification for a wide variety of applications, including security document protection, object tracking, pharmaceutical security, supermarket automation, interactive product labels, web-browsing from printed surfaces, paper based email, and many others.

[0371] Using Memjet™ digital printing technology (which is the subject of a number of pending U.S. patent applications including U.S. Ser. No. 10/407,212), Hyperlabel tags are printed over substantially an entire surface, such as a security document, bank note, or pharmaceutical packaging, using infrared (IR) ink. By printing the tags in infrared-absorptive ink on any substrate which is infrared-reflective, the near-infrared wavelengths, and hence the tags are invisible to the human eye but are easily sensed by a solid-state image sensor with an appropriate filter. This allows machine readable information to be encoded over a large portion of the note or other surface, with no visible effect on the original note text or graphics thereon. A scanning laser or image sensor can read the tags on any part of the surface to performs associated actions, such as validating each individual note or item.

[0372] An example of such a Hyperlabel encoded document, is shown in FIG. 1. In this example, the Hyperlabel document consists of graphic data 2 printed using visible ink, and coded data 3 formed from Hyperlabel tags 4. The document includes an interactive element 6 defined by a zone 7 which corresponds to the spatial extent of a corresponding graphic 8. In use, the tags encode tag data including an ID. By sensing at least one tag, and determining and interpreting the encoded ID using an appropriate system, this allows the associated actions to be performed.

[0373] In one example, a tag map is used to define a layout of the tags on the Hyperlabel document based on the ID encoded within the tag data. The ID can also be used to reference a document description which describes the individual elements of the Hyperlabel document, and in particular describes the type and spatial extent (zone) of interactive elements, such as a button or text field. Thus, in this example, the element 6 has a zone 7 which corresponds to the spatial extent of a corresponding graphic 8. This allows a computer system to interpret interactions with the Hyperlabel document.

[0374] In position indicating techniques, the ID encoded within the tag data of each tag allows the exact position of the tag on the Hyperlabel document to be determined from the tag map. The position can then be used to determine whether the sensed tag is positioned in a zone of an interactive element from the document description.

[0375] In object indicating techniques, the ID encoded within the tag data allows the presence of the tag in a region of the document to be determined from the tag map (the relative position of the tag within the region may also be indicated). In this case, the document description can be used to determine whether the region corresponds to the zone of an interactive element.

[0376] An example of this process will now be described with reference to FIGS. 2 and 3 which show how a sensing device in the form of a Netpage pen or Hyperlabel reader 101, which interacts with the coded data on a printed Hyperlabel document 1, such as a security document, label, product packaging or the like. An product item 200 carrying a Hyperlabel tags is also shown in FIG. 2.

[0377] The Hyperlabel reader 401 senses a tag using an area image sensor and detects tag data. The Hyperlabel reader 101 uses the sensed data tag to generate interaction data which is transmitted via a short-range radio link 9 to a relay 44, which may form part of a computer 75 or a printer 601. The relay sends the interaction data, via a network 19, to a document server 10, which uses the ID to access the document description, and interpret the interaction. In appropriate circumstances, the document server sends a corresponding message to an application server 13, which can then perform a corresponding action.

[0378] In an alternative embodiment, the PC, Web terminal, netpage printer or relay device may communicate directly with local or remote application software, including a local or remote Web server. Relatedly, output is not limited to being printed by the netpage printer. It can also be displayed on the PC or Web terminal, and further interaction can be screen-based rather than paper-based, or a mixture of the two.

[0379] Typically Netpage pen users register with a registration server 11, which associates the user with an identifier stored in the respective Netpage pen. By providing the sensing device identifier as part of the interaction data, this allows users to be identified, allowing transactions or the like to be performed.

[0380] Hyperlabel documents are generated by having an ID server generate an ID which is transferred to the document server 10. The document server 10 determines a document description and then records an association between the document description and the ID, to allow subsequent retrieval of the document description using the ID.

[0381] The ID is then used to generate the tag data, as will be described in more detail below, before the document is printed by the Hyperlabel printer 601, using the page description and the tag map.

[0382] Each tag is represented by a pattern which contains two kinds of elements. The first kind of element is a target. Targets allow a tag to be located in an image of a coded surface, and allow the perspective distortion of the tag to be inferred. The second kind of element is a macrodot. Each macrodot encodes the value of a bit by its presence or absence.

[0383] The pattern is represented on the coded surface in such a way as to allow it to be acquired by an optical imaging system, and in particular by an optical system with a narrowband response in the near-infrared. The pattern is typically printed onto the surface using a narrowband near-infrared ink.

[0384] In the Hyperlabel system the region typically corresponds to the surface of an entire product item, or to a security document, and the region ID corresponds to the unique item ID. For clarity in the following discussion we refer to items and item IDs (or simply IDs), with the understanding that the item ID corresponds to the region ID.

[0385] The surface coding is designed so that an acquisition field of view large enough to guarantee acquisition of an entire tag is large enough to guarantee acquisition of the ID of the region containing the tag. Acquisition of the tag itself guarantees acquisition of the tag's two-dimensional position within the region, as well as other tag-specific data. The surface coding therefore allows a sensing device to acquire a region ID and a tag position during a purely local interaction with a coded surface, e.g. during a “click” or tap on a coded surface with a pen.

[0386] A wide range of different tag structures can be used, and some examples will now be described.

[0387] FIG. 4 shows the structure of a complete tag. Each of the four black circles is a target. The tag, and the overall pattern, has four-fold rotational symmetry at the physical level.

[0388] Each square region represents a symbol, and each symbol represents four bits of information.

[0389] FIG. 5 shows the structure of a symbol. It contains four macrodots, each of which represents the value of one bit by its presence (one) or absence (zero).

[0390] The macrodot spacing is specified by the parameter s throughout this document. It has a nominal value of 143 μm, based on 9 dots printed at a pitch of 1600 dots per inch. However, it is allowed to vary by ±10% according to the capabilities of the device used to produce the pattern.

[0391] FIG. 6 shows an array of nine adjacent symbols. The macrodot spacing is uniform both within and between symbols.

[0392] FIG. 7 shows the ordering of the bits within a symbol. Bit zero is the least significant within a symbol; bit three is the most significant. Note that this ordering is relative to the orientation of the symbol. The orientation of a particular symbol within the tag is indicated by the orientation of the label of the symbol in the tag diagrams. In general, the orientation of all symbols within a particular segment of the tag have the same orientation, consistent with the bottom of the symbol being closest to the centre of the tag.

[0393] Only the macrodots are part of the representation of a symbol in the pattern. The square outline of a symbol is used in this document to more clearly elucidate the structure of a tag. FIG. 8, by way of illustration, shows the actual pattern of a tag with every bit set. Note that, in practice, every bit of a tag can never be set.

[0394] A macrodot is nominally circular with a nominal diameter of (5/9)s. However, it is allowed to vary in size by ±10% according to the capabilities of the device used to produce the pattern.

[0395] A target is nominally circular with a nominal diameter of (17/9)s. However, it is allowed to vary in size by ±10% according to the capabilities of the device used to produce the pattern.

[0396] The tag pattern is allowed to vary in scale by up to ±10% according to the capabilities of the device used to produce the pattern. Any deviation from the nominal scale is recorded in the tag data to allow accurate generation of position samples.

[0397] Each symbol shown in the tag structure in FIG. 4 has a unique label. Each label consists an alphabetic prefix and a numeric suffix.

Tag Group

[0398] Tags are arranged into tag groups. Each tag group contains four tags arranged in a square. Each tag therefore has one of four possible tag types according to its location within the tag group square. The tag types are labelled 00, 10, 01 and 11, as shown in FIG. 9.

[0399] FIG. 10 shows how tag groups are repeated in a continuous tiling of tags. The tiling guarantees the any set of four adjacent tags contains one tag of each type.

Codewords

[0400] The tag contains four complete codewords. Each codeword is of a punctured 2⁴-ary (8,5) Reed-Solomon code.

[0401] Two of the codewords are unique to the tag. These are referred to as local and are labelled A and B. The tag therefore encodes up to 40 bits of information unique to the tag.

[0402] The remaining two codewords are unique to a tag type, but common to all tags of the same type within a contiguous tiling of tags. These are referred to as global and are labelled C and D, subscripted by tag type. A tag group therefore encodes up to 160 bits of information common to all tag groups within a contiguous tiling of tags.

[0403] The layout of the four codewords is shown in FIG. 11.

Reed-Solomon Encoding

[0404] Codewords are encoded using a punctured 2⁴-ary (8,5) Reed-Solomon code.

[0405] A 2⁴-ary (8,5) Reed-Solomon code encodes 20 data bits (i.e. five 4-bit symbols) and 12 redundancy bits (i.e. three 4-bit symbols) in each codeword. Its error-detecting capacity is three symbols. Its error-correcting capacity is one symbol.

[0406] As shown in FIG. 12, codeword coordinates are indexed in coefficient order, and the data bit ordering follows the codeword bit ordering.

[0407] A punctured 2⁴-ary (8,5) Reed-Solomon code is a 2⁴-ary (15,5) Reed-Solomon code with seven redundancy coordinates removed. The removed coordinates are the most significant redundancy coordinates.

[0408] The code has the following primitive polynominal:
p(x)=x⁴+x+1
The code has the following generator polynominal:
g(x)=(x+α)(x+α²) . . . (x+α¹⁰)
For a detailed description of Reed-Solomon codes, refer to Wicker, S. B. and V. K. Bhargava, eds., Reed-Solomon Codes and Their Applications, IEEE Press, 1994.
Tag Coordinate Space

[0409] The tag coordinate space has two orthogonal axes labelled x and y respectively. When the positive x axis points to the right then the positive y axis points down.

[0410] The surface coding does not specify the location of the tag coordinate space origin on a particular tagged surface, nor the orientation of the tag coordinate space with respect to the surface. This information is application-specific. For example, if the tagged surface is a sheet of paper, then the application which prints the tags onto the paper may record the actual offset and orientation, and these can be used to normalise any digital ink subsequently captured in conjunction with the surface.

[0411] The position encoded in a tag is defined in units of tags. By convention, the position is taken to be the position of the centre of the target closest to the origin.

Tag Information Content

[0412] Table 1 defines the information fields embedded in the surface coding. Table 2 defines how these fields map to codewords.

TABLE 1
Field definitions
Field	width	description
per codeword
codeword type	2	The type of the codeword, i.e. one of A (b′00′), B (b′01′),
		C (b′10′) and D (b′11′).
per tag
tag type	2	The type of the tag, i.e. one of 00 (b′00′), 01 (b′01′), 10
		(b′10′) and 11 (b′11′) - corresponds to the bottom two bits
		of the x and y coordinates of the tag.
x coordinate	13	The unsigned x coordinate of the tag allows a maximum
		coordinate value of approximately 14 m.
y coordinate	13	The unsigned y coordinate of the tagb.
active area flag	1	A flag indicating whether the tag is a member of an active
		area. b′1′ indicates membership.
active area map flag	1	A flag indicating whether an active area map is present.
		b′1′ indicates the presence of a map (see next field). If the
		map is absent then the value of each map entry is derived
		from the active area flag (see previous field).
active area map	8	A map1of which of the tag's immediate eight neighbours
		are members of an active area. b′1′ indicates membership
		(FIG. 13 indicates the bit ordering of the map)
data fragment	8	A fragment of an embedded data stream. Only present if
		the active area map is absent.
per tag group
encoding format	8	The format of the encoding.
		0: the present encoding
		Other values are TBA.
Region flags	8	Flags controlling the interpretation and routing of region-
		related information.
		0: region ID is an EPC
		1: region is linked
		2: region is interactive
		3: region is signed
		4: region includes data
		5: region relates to mobile application
		Other bits are reserved and must be zero.
tag size adjustment	16	The difference between the actual tag size and the nominal
		tag size (1.7145 mm (based on 1600 dpi, 9 dots per
		macrodot, and 12 macrodots per tag)), in 10 nm units, in
		sign-magnitude format.
Region ID	96	The ID of the region containing the tags.
CRC	16	A CRC of tag group data (CCITT CRC-16 (ITU, Interface
		between Data Terminal Equipment (DTE) and Data
		Circuit-terminating Equipment (DCE) for terminals
		operating in the packet mode and connected to public data
		networks by dedicated circuit, ITU-T X.25 (10/96))
Total	320

[0413] The active area map indicates whether the corresponding tags are members of an active area. An active area is an area within which any captured input should be immediately forwarded to the corresponding Hyperlabel server for interpretation. It also allows the Hyperlabel sensing device to signal to the user that the input will have an immediate effect.

TABLE 2
Mapping of fields to codewords
	codeword			field
codeword	bits	field	Width	bits
A	1:0	codeword type (b′00′)	2	all
	10:2	x coordinate	9	12:4
	19:11	Y coordinate	9	12:4
B	1:0	codeword type (b′01′)	2	all
	2	tag type	1	0
	5:2	x coordinate	4	3:0
	6	tag type	1	1
	9:6	y coordinate	4	3:0
	10	active area flag	1	all
	11	active area map flag	1	all
	19:12	active area map	8	all
	19:12	data fragment	8	all
C00	1:0	codeword type (b′10′)	2	all
	9:2	encoding format	8	all
	17:10	region flags	8	all
	19:18	tag size adjustment	2	1:0
C01	1:0	codeword type (b′10′)	2	all
	15:2	tag size adjustment	14	15:2
	19:16	region ID	4	3:0
C10	1:0	codeword type (b′10′)	2	all
	19:2	region ID	18	21:4
C11	1:0	codeword type (b′10′)	2	all
	19:2	region ID	18	39:22
D00	1:0	codeword type (b′11′)	2	all
	19:2	region ID	18	57:40
D01	1:0	codeword type (b′11′)	2	all
	19:2	region ID	18	75:58
D10	1:0	codeword type (b′11′)	2	all
	19:2	region ID	18	93:76
D11	1:0	codeword type (b′11′)	2	all
	3:2	region ID	2	95:94
	19:4	CRC	16	all

[0414] Note that the tag type can be moved into a global codeword to maximise local codeword utilization. This in turn can allow larger coordinates and/or 16-bit data fragments (potentially configurably in conjunction with coordinate precision). However, this reduces the independence of position decoding from region ID decoding and has not been included in the specification at this time.

Embedded Data

[0415] If the “region includes data” flag in the region flags is set then the surface coding contains embedded data. The data is encoded in multiple contiguous tags' data fragments, and is replicated in the surface coding as many times as it will fit.

[0416] The embedded data is encoded in such a way that a random and partial scan of the surface coding containing the embedded data can be sufficient to retrieve the entire data. The scanning system reassembles the data from retrieved fragments, and reports to the user when sufficient fragments have been retrieved without error.

[0417] As shown in Table 3, a 200-bit data block encodes 160 bits of data. The block data is encoded in the data fragments of A contiguous group of 25 tags arranged in a 5×5 square. A tag belongs to a block whose integer coordinate is the tag's coordinate divided by 5. Within each block the data is arranged into tags with increasing x coordinate within increasing y coordinate.

[0418] A data fragment may be missing from a block where an active area map is present. However, the missing data fragment is likely to be recoverable from another copy of the block.

[0419] Data of arbitrary size is encoded into a superblock consisting of a contiguous set of blocks arranged in a rectangle. The size of the superblock is encoded in each block. A block belongs to a superblock whose integer coordinate is the block's coordinate divided by the superblock size. Within each superblock the data is arranged into blocks with increasing x coordinate within increasing y coordinate.

[0420] The superblock is replicated in the surface coding as many times as it will fit, including partially along the edges of the surface coding.

[0421] The data encoded in the superblock may include more precise type information, more precise size information, and more extensive error detection and/or correction data.

TABLE 3
Embedded data block
field	width	description
data type	8	The type of the data in the superblock.
		Values include:
		0: type is controlled by region flags
		1: MIME
		Other values are TBA.
superblock width	8	The width of the superblock, in blocks.
superblock height	8	The height of the superblock, in blocks.
data	160	The block data.
CRC	16	A CRC of the block data.
total	200

Alternative First Example Tag Structure
Tag Group

[0422] Tags are arranged into tag groups. Each tag group contains four tags arranged in a square. Each tag therefore has one of four possible tag types according to its location within the tag group square. The tag types are labelled 00, 10, 01 and 11, as shown in FIG. 14.

[0423] Each tag in the tag group is rotated as shown in the figure, i.e. tag type 00 is rotated 0 degrees, tag type 10 is rotated 90 degrees, tag type 11 is rotated 180 degrees, and tag type 01 is rotated 270 degrees.

[0424] FIG. 15 shows how tag groups are repeated in a continuous tiling of tags. The tiling guarantees the any set of four adjacent tags contains one tag of each type.

Orientation-Indicating Cyclic Position Code

[0425] The tag contains a 2⁴-ary (4, 1) cyclic position codeword which can be decoded at any of the four possible orientations of the tag to determine the actual orientation of the tag. Symbols which are part of the cyclic position codeword have a prefix of “R” and are numbered 0 to 3 in order of increasing significance.

[0426] The cyclic position codeword is (0, 7, 9, E₁₆) Note that it only uses four distinct symbol values, even though a four-bit symbol has sixteen possible values. During decoding, any unused symbol value should, if detected, be treated as an erasure. To maximise the probability of low-weight bit error patterns causing erasures rather than symbol errors, the symbol values are chosen to be as evenly spaced on the hypercube as possible.

[0427] The minimum distance of the cyclic position code is 4, hence its error-correcting capacity is one symbol in the presence of up to one erasure, and no symbols in the presence of two or more erasures.

[0428] The layout of the orientation-indicating cyclic position codeword is shown in FIG. 16.

Local Codeword

[0429] The tag locally contains one complete codeword which is used to encode information unique to the tag. The codeword is of a punctured 2⁴-ary (13, 7) Reed-Solomon code. The tag therefore encodes up to 28 bits of information unique to the tag.

[0430] The layout of the local codeword is shown in FIG. 17.

Distributed Codewords

[0431] The tag also contains fragments of four codewords which are distributed across the four adjacent tags in a tag group and which are used to encode information common to a set of contiguous tags. Each codeword is of a 2⁴-ary (15,11) Reed-Solomon code. Any four adjacent tags therefore together encode up to 176 bits of information common to a set of contiguous tags.

[0432] The layout of the four complete codewords, distributed across the four adjacent tags in a tag group, is shown in FIG. 18. The order of the four tags in the tag group in FIG. 18 is the order of the four tags in FIG. 14.

[0433] FIG. 19 shows the layout of a complete tag group.

Reed-Solomon Encoding—Local Codeword

[0434] The local codeword is encoded using a punctured 2⁴-ary (13, 7) Reed-Solomon code. The code encodes 28 data bits (i.e. seven symbols) and 24 redundancy bits (i.e. six symbols) in each codeword. Its error-detecting capacity is six symbols. Its error-correcting capacity is three symbols.

[0435] As shown in FIG. 20, codeword coordinates are indexed in coefficient order, and the data bit ordering follows the codeword bit ordering.

[0436] The code is a 2⁴-ary (15, 7) Reed-Solomon code with two redundancy coordinates removed. The removed coordinates are the most significant redundancy coordinates. The code has the following primitive polynominal:
p(x)=x⁴+x+1  (EQ 1)
The code has the following generator polynominal:
g(x)=(x+α)(x+α²) . . . (x+α⁸)  (EQ 2)
Reed-Solomon Encoding—Distributed Codewords

[0437] The distributed codewords are encoded using a 2⁴-ary (15, 11) Reed-Solomon code. The code encodes 44 data bits (i.e. eleven symbols) and 16 redundancy bits (i.e. four symbols) in each codeword. Its error-detecting capacity is four symbols. Its error-correcting capacity is two symbols.

[0438] Codeword coordinates are indexed in coefficient order, and the data bit ordering follows the codeword bit ordering.

[0439] The code has the same primitive polynominal as the local codeword code.

[0440] The code has the following generator polynominal:
g(x)=(x+α)(x+α²) . . . (x+α⁴)  (EQ 3)
Tag Coordinate Space

[0441] The tag coordinate space has two orthogonal axes labelled x and y respectively. When the positive x axis points to the right then the positive y axis points down.

[0442] The surface coding does not specify the location of the tag coordinate space origin on a particular tagged surface, nor the orientation of the tag coordinate space with respect to the surface. This information is application-specific. For example, if the tagged surface is a sheet of paper, then the application which prints the tags onto the paper may record the actual offset and orientation, and these can be used to normalise any digital ink subsequently captured in conjunction with the surface.

[0443] The position encoded in a tag is defined in units of tags. By convention, the position is taken to be the position of the centre of the target closest to the origin.

Tag Information Content

Field Definitions

[0444] Table 4 defines the information fields embedded in the surface coding. Table 5 defines how these fields map to codewords.

TABLE 4
Field definitions
	width
field	(bits)	description
per tag
x coordinate	9 or 13	The unsigned x coordinate of the tag allows
		maximum coordinate values of approximately 0.9 m
		and 14 m respectively.
y coordinate	9 or 13	The unsigned y coordinate of the tag allows
		maximum coordinate values of approximately 0.9 m
		and 14 m respectively
active area flag	1	A flag indicating whether the area (the diameter of
		the area, centered on the tag, is nominally 5 times the
		diagonal size of the tag) immediately surrounding the
		tag intersects an active area.
		b′1′ indicates intersection.
data fragment flag	1	A flag indicating whether a data fragment is present
		(see next field).
		b′1′ indicates the presence of a data fragment.
		If the data fragment is present then the width of the x
		and y coordinate fields is 9. If it is absent then the
		width is 13.
data fragment	0 or 8	A fragment of an embedded data stream.
per tag group
(i.e. per region)
encoding format	8	The format of the encoding.
		0: the present encoding
		Other values are reserved.
region flags	8	Flags controlling the interpretation of region data.
		0: region ID is an EPC
		1: region has signature
		2: region has embedded data
		3: embedded data is signature
		Other bits are reserved and must be zero.
tag size ID	8	The ID of the tag size.
		0: the present tag size the nominal tag size is
		1.7145 mm, based on 1600 dpi, 9 dots per
		macrodot, and 12 macrodots per tag
		Other values are reserved.
region ID	96	The ID of the region containing the tags.
signature	36	The signature of the region.
high-order coordinate	4	The width of the high-order part of the x and y
width (w)		coordinates of the tag.
high-order x coordinate	0 to 15	High-order part of the x coordinate of the tag
		expands the maximum coordinate values to
		approximately 2.4 km and 38 km respectively
high-order y coordinate	0 to 15	High-order part of the y coordinate of the tag expands
		the maximum coordinate values to
		approximately 2.4 km and 38 km respectively.
CRC	16	A CRC of tag group data.

[0445] An active area is an area within which any captured input should be immediately forwarded to the corresponding Hyperlabel server for interpretation. This also allows the Hyperlabel server to signal to the user that the input has had an immediate effect. Since the server has access to precise region definitions, any active area indication in the surface coding can be imprecise so long as it is inclusive.

[0446] The width of the high-order coordinate fields, if non-zero, reduces the width of the signature field by a corresponding number of bits. Full coordinates are computed by prepending each high-order coordinate field to its corresponding coordinate field.

TABLE 5
Mapping of fields to codewords
	codeword			field
codeword	bits	field	width	bits
A	12:0	x coordinate	13	all
	12:9	data fragment	4	3:0
	25:13	y coordinate	13	all
	25:22	data fragment	4	7:4
	26	active area flag	1	all
	27	data fragment flag	1	all
B	7:0	encoding format	8	all
	15:8	region flags	8	all
	23:16	tag size ID	8	all
	39:24	CRC	16	all
	43:40	high-order coordinate	4	3:0
		width (w)
C	35:0	signature	36	all
	(35−w):(36−2w)	high-order x coordinate	w	all
	35:(36−w)	high-order y coordinate	w	all
	43:36	region ID	8	7:0
D	43:0	region ID	44	51:8
E	43:0	region ID	44	95:52

Embedded Data

[0447] If the “region has embedded data” flag in the region flags is set then the surface coding contains embedded data. The data is encoded in multiple contiguous tags' data fragments, and is replicated in the surface coding as many times as it will fit.

[0448] The embedded data is encoded in such a way that a random and partial scan of the surface coding containing the embedded data can be sufficient to retrieve the entire data. The scanning system reassembles the data from retrieved fragments, and reports to the user when sufficient fragments have been retrieved without error.

[0449] As shown in Table 6, a 200-bit data block encodes 160 bits of data. The block data is encoded in the data fragments of a contiguous group of 25 tags arranged in a 5×5 square. A tag belongs to a block whose integer coordinate is the tag's coordinate divided by 5. Within each block the data is arranged into tags with increasing x coordinate within increasing y coordinate.

[0450] A data fragment may be missing from a block where an active area map is present. However, the missing data fragment is likely to be recoverable from another copy of the block.

[0451] Data of arbitrary size is encoded into a superblock consisting of a contiguous set of blocks arranged in a rectangle. The size of the superblock is encoded in each block. A block belongs to a superblock whose integer coordinate is the block's coordinate divided by the superblock size. Within each superblock the data is arranged into blocks with increasing x coordinate within increasing y coordinate.

[0452] The superblock is replicated in the surface coding as many times as it will fit, including partially along the edges of the surface coding.

[0453] The data encoded in the superblock may include more precise type information, more precise size information, and more extensive error detection and/or correction data.

TABLE 6
Embedded data block
field	width	description
data type	8	The type of the data in the superblock.
		Values include:
		0: type is controlled by region flags
		1: MIME
		Other values are TBA.
superblock width	8	The width of the superblock, in blocks.
superblock height	8	The height of the superblock, in blocks.
data	160	The block data.
CRC	16	A CRC of the block data.
total	200

[0454] It will be appreciated that any form of embedded data may be used, including for example, text, image, audio, video data, such as product information, application data, contact data, business card data, and directory data.

Region Signatures

[0455] If the “region has signature” flag in the region flags is set then the signature field contains a signature with a maximum width of 36 bits. The signature is typically a random number associated with the region ID in a secure database. The signature is ideally generated using a truly random process, such as a quantum process, or by distilling randomness from random events.

[0456] In an online environment the signature can be validated, in conjunction with the region ID, by querying a server with access to the secure database.

[0457] If the “region has embedded data” and “embedded data is signature” flags in the region flags are set then the surface coding contains a 160-bit cryptographic signature of the region ID. The signature is encoded in a one-block superb lock.

[0458] In an online environment any number of signature fragments can be used, in conjunction with the region ID and optionally the random signature, to validate the signature by querying a server with knowledge of the full signature or the corresponding private key.

[0459] In an offline (or online) environment the entire signature can be recovered by reading multiple tags, and can then be validated using the corresponding public signature key.

[0460] Signature verification is discussed in more detail below.

[0461] FIG. 21 shows the structure of a complete tag. Each of the six black circles is a target. The tag, and the overall pattern, has six-fold rotational symmetry at the physical level.

[0462] Each diamond-shaped region represents a symbol, and each symbol represents four bits of information.

[0463] FIG. 22 shows the structure of a symbol. It contains four macrodots, each of which represents the value of one bit by its presence (one) or absence (zero).

[0464] The macrodot spacing is specified by the parameter s throughout this document. It has a nominal value of 143 μm, based on 9 dots printed at a pitch of 1600 dots per inch. However, it is allowed to vary by ±10% according to the capabilities of the device used to produce the pattern.

[0465] FIG. 23 shows an array of five adjacent symbols. The macrodot spacing is uniform both within and between symbols.

[0466] FIG. 24 shows the ordering of the bits within a symbol. Bit zero is the least significant within a symbol; bit three is the most significant. Note that this ordering is relative to the orientation of the symbol. The orientation of a particular symbol within the tag is indicated by the orientation of the label of the symbol in the tag diagrams. In general, the orientation of all symbols within a particular segment of the tag have the same orientation, consistent with the bottom of the symbol being closest to the centre of the tag.

[0467] Only the macrodots are part of the representation of a symbol in the pattern. The diamond-shaped outline of a symbol is used in this document to more clearly elucidate the structure of a tag. FIG. 25, by way of illustration, shows the actual pattern of a tag with every bit set. Note that, in practice, every bit of a tag can never be set.

[0468] A macrodot is nominally circular with a nominal diameter of (5/9)s. However, it is allowed to vary in size by ±10% according to the capabilities of the device used to produce the pattern.

[0469] A target is nominally circular with a nominal diameter of (17/9)s. However, it is allowed to vary in size by 10% according to the capabilities of the device used to produce the pattern.

[0470] The tag pattern is allowed to vary in scale by tip to ±10% according to the capabilities of the device used to produce the pattern. Any deviation from the nominal scale is recorded in the tag data to allow accurate generation of position samples.

[0471] Each symbol shown in the tag structure in FIG. 21 has a unique label. Each label consists an alphabetic prefix and a numeric suffix.

Tag Group

[0472] Tags are arranged into tag groups. Each tag group contains three tags arranged in a line. Each tag therefore has one of three possible tag types according to its location within the tag group. The tag types are labelled P, Q and R, as shown in FIG. 26.

[0473] FIG. 27 shows how tag groups are repeated in a continuous tiling of tags. The tiling guarantees the any set of three adjacent tags contains one tag of each type.

Orientation-Indicating Cyclic Position Code

[0474] The tag contains a 2³-ary (6,1) cyclic position codeword (this work is currently the subject of two pending US Patent applications, entitled “Cyclic position codes” and “Orientation indicating cyclic position codes” with application Ser. Nos. 10/120,441 and 10/409,864, respectively) which can be decoded at any of the six possible orientations of the tag to determine the actual orientation of the tag. Symbols which are part of the cyclic position codeword have a prefix of “R” and are numbered 0 to 5 in order of increasing significance.

[0475] The layout of the orientation-indicating cyclic position codeword is shown in FIG. 28.

[0476] The cyclic position codeword is (0,5,6,9,A₁₆,F₁₆). Note that it only uses six distinct symbol values, even though a four-bit symbol has sixteen possible values. During decoding, any unused symbol value should, if detected, be treated as an erasure. To maximise the probability of low-weight bit error patterns causing erasures rather than symbol errors, the symbol values are chosen to be evenly-spaced on the hypercube.

[0477] The minimum distance of the cyclic position code is 6, hence its error-correcting capacity is two symbols in the presence of up to one erasure, one symbol in the presence of two or three erasures, and no symbols in the presence of four or more erasures.

Local Codeword

[0478] The tag locally contains one complete codeword, labelled A, which is used to encode information unique to the tag. The codeword is of a punctured 2⁴-ary (12,7) Reed-Solomon code. The tag therefore encodes up to 28 bits of information unique to the tag.

[0479] The layout of the local codeword is shown in FIG. 29.

Distributed Codewords

[0480] The tag also contains fragments of six codewords, labelled B through G, which are distributed across three adjacent tags and which are used to encode information common to a set of contiguous tags. Each codeword is of a punctured 2⁴-ary (12,7) Reed-Solomon code. Any three adjacent tags therefore together encode up to 168 bits of information common to a set of contiguous tags.

[0481] The layout of the first four fragments of the six codewords B through G in tag type P is shown in FIG. 30. The layout in the other tag types follows the layout in tag type P, with symbols 4 through 7 in tag type Q, and fragments 8 through 11 in tag type Q.

[0482] The layout of the six complete codewords B through G, distributed across the three tag types P, Q and R, is shown in FIG. 31.

[0483] As shown earlier in FIG. 27, the tiling guarantees the any set of three adjacent tags contains one tag of each type, and therefore contains a complete set of distributed codewords. The tag type, used to determine the registration of the distributed codewords with respect to a particular set of adjacent tags, is inferred from the x-y coordinate encoded in the local codeword of each tag.

Tag Segment Geometry

[0484] FIG. 32 shows the geometry of a tag segment.

[0485] FIG. 33 shows the spacing d between tag segments, required to maintain consistent spacing between macrodots, where d is given by:
d=(1−√{square root over (3)}/2)s

[0486] FIG. 34 shows the effect of the inter-segment spacing don target position. Compared with their nominal positions in relation to closely-packed segments (i.e. with d=0), diagonal targets must be displaced by
(Δ_x, Δ_y)=(±1/√{square root over (3)},±1)d,
and horizontal targets must be displaced by
(Δ_x,Δ_y)=(±2/√{square root over (3)},0)d.
Reed-Solomon Encoding

[0487] Codewords are encoded using a punctured 2⁴-ary (12,7) Reed-Solomon code. A 2⁴-ary (12,7) Reed-Solomon code encodes 28 data bits (i.e. seven 4-bit symbols) and 20 redundancy bits (i.e. five 4-bit symbols) in each codeword. Its error-detecting capacity is five symbols. Its error-correcting capacity is two symbols.

[0488] As shown in FIG. 35, codeword coordinates are indexed in coefficient order, and the data bit ordering follows the codeword bit ordering.

[0489] A punctured 2⁴-ary (12,7) Reed-Solomon code is a 2⁴-ary (15,7) Reed-Solomon code with three redundancy coordinates removed. The removed coordinates are the most significant redundancy coordinates.

[0490] The code has the following primitive polynominal:
p(x)=x⁴+x+1

[0491] The code has the following generator polynominal:
g(x)=(x+α)(x+α²) . . . (x+α⁸)

[0492] For a detailed description of Reed-Solomon codes, refer to Wicker, S. B. and V. K. Bhargava, eds., Reed-Solomon Codes and Their Applications, IEEE Press, 1994.

Tag Coordinate Space

[0493] The tag coordinate space has two orthogonal axes labelled x and y respectively. When the positive x axis points to the right then the positive y axis points down.

[0494] The surface coding does not specify the location of the tag coordinate space origin on a particular tagged surface, nor the orientation of the tag coordinate space with respect to the surface. This information is application-specific. For example, if the tagged surface is a sheet of paper, then the application which prints the tags onto the paper may record the actual offset and orientation, and these can be used to normalise any digital ink subsequently captured in conjunction with the surface.

[0495] The position encoded in a tag is defined in units of tags. Tag coordinates are arranged as shown in in FIG. 36, where the tag with coordinate (0,0) is a P type tag. By convention, the position of a tag with an even y coordinate is defined to be the position of the center of the tag. The position of a tag with an odd y coordinate is therefore defined to be the position of the midpoint between the center of the tag and the center of its neighboring tag on the left. Horizontal and vertical tag units, based on center-to-center tag tag spacings, are given by: $u_x=4\left(2\sqrt{3}s\right)+2d\cong 14.1s$ $u_y=6\left(2s\right)+2\left(d\frac{\sqrt{3}}{2}\right)\cong 12.2s$
where d is the inter-segment spacing given by
d=(1−√{square root over (3)}/2)s

[0496] If the three tag types P, Q and R are assigned values 0, 1 and 2 respectively, then the type^t of a tag is inferred from its (x,y) coordinate as follows. If y is even, then:
t=x modulo 3
if y is odd, then:
t=(x−1) modulo 3
Tag Information Content

[0497] Table 7 defines the information fields embedded in the surface coding. Table 8 defines how these fields map to codewords.

TABLE 7
Field Definitions
field	width	description
per tag
X coordinate	10	The unsigned x coordinate of the tag allows a
		maximum x coordinate value of approximately 2.1 m
		(based on EQ 4).
Y coordinate	10	The unsigned y coordinate of the tag allows a
		maximum y coordinate value of approximately 1.8 m
		(based on EQ 5.
active area flag	1	flag indicating whether the tag is a member of an
		active area. b′1′ indicates membership.
active area map flag	1	flag indicating whether an active area map is
		present. b′1′ indicates the presence of a map (see
		next field). If the map is absent then the value of each
		map entry is derived from the active area flag (see
		previous field).
active area map	6	A map of which of the tag's immediate six
		neighbours are members of an active area. b′1′
		indicates membership - FIG. 37 indicates the bit
		ordering of the map
data fragment	6	A fragment of an embedded data stream. Only
		present if the active area map is absent.
per tag group
encoding format	12	The format of the encoding.
		0: the present encoding
		Other values are TBA.
macrodot spacing adjustment	16	The difference between the actual macrodot spacing
		and the nominal macrodot spacing, in nm units, in
		sign-magnitude format - the nominal macrodot
		spacing is 142875 nm (based on 1600 dpi and 9 dots
		per macrodot)
region flags	12	Flags controlling the interpretation and routing of
		region-related information.
		0: region ID is an EPC
		1: region is linked
		2: region is interactive
		3: region is signed
		4: region includes data
		5: region relates to mobile application
		Other bits are reserved and must be zero.
region ID	112	The ID of the region containing the tags.
CRC	16	A CRC (CCITT CRC-16) of tag group data.

[0498] The active area map indicates whether the corresponding tags are members of an active area. An active area is an area within which any captured input should be immediately forwarded to the corresponding Hyperlabel server for interpretation. It also allows the Hyperlabel sensing device to signal to the user that the input will have an immediate effect.

TABLE 8
Mapping of fields to codewords
	codeword	field	field
codeword	bits	width	bits	field
A	9:0	10	all	x coordinate
	19:10	10	all	y coordinate
	20	1	all	active area flag
	21	1	all	active area map flag
	27:22	6	all	active area map
	27:22	6	all	data fragment
B	11:0	12	all	Encoding format
	27:12	16	all	Macrodot spacing
				adjustment
C	11:0	12	all	region flags
	27:12	16	27:12	region ID
D	27:0	28	55:28
E	27:0	28	83:56
F	27:0	28	111:84
G	11:0	12	11:0
	27:12	16	all	CRC

Embedded Data

[0499] If the “region includes data” flag in the region flags is set then the surface coding contains embedded data. The data is encoded in multiple contiguous tags' data fragments, and is replicated in the surface coding as many times as it will fit.

[0500] The embedded data is encoded in such a way that a random and partial scan of the surface coding containing the embedded data can be sufficient to retrieve the entire data. The scanning system reassembles the data from retrieved fragments, and reports to the user when sufficient fragments have been retrieved without error.

[0501] As shown in Table 9, a 216-bit data block encodes 160 bits of data.

TABLE 9
Embedded data block
field	width	Description
data type	16	The type of the data in the superblock.
		Values include:
		0: type is controlled by region flags
		1: MIME
		Other values are TBA.
superblock width	12	The width of the superblock, in blocks.
superblock height	12	The height of the superblock, in blocks.
data	160	The block data.
CRC	16	A CRC of the block data.
total	216

[0502] The block data is encoded in the data fragments of a contiguous group of 36 tags arranged in a 6×6 square as shown in FIG. 38. A tag belongs to a block whose integer x and y coordinates are the tag's x and y coordinates divided by 6. Within each block the data is arranged into tags with increasing x coordinate within increasing y coordinate.

[0503] A data fragment may be missing from a block where an active area map is present. However, the missing data fragment is likely to be recoverable from another copy of the block.

[0504] Data of arbitrary size is encoded into a superblock consisting of a contiguous set of blocks arranged in a rectangle. The size of the superblock is encoded in each block. A block belongs to a superblock whose integer coordinate is the block's coordinate divided by the superblock size. Within each superblock the data is arranged into blocks with increasing x coordinate within increasing y coordinate.

[0505] The superblock is replicated in the surface coding as many times as it will fit, including partially along the edges of the surface coding.

[0506] The data encoded in the superblock may include more precise type information, more precise size information, and more extensive error detection and/or correction data.

General Considerations

Cryptographic Signature of Region ID

[0507] If the “region is signed” flag in the region flags is set then the surface coding contains a 160-bit cryptographic signature of the region ID. The signature is encoded in a one-block superblock.

[0508] In an online environment any signature fragment can be used, in conjunction with the region ID, to validate the signature. In an offline environment the entire signature can be recovered by reading multiple tags, and can then be validated using the corresponding public signature key.

Mime Data

[0509] If the embedded data type is “MIME” then the superblock contains Multipurpose Internet Mail Extensions (MIME) data according to RFC 2045 (Freed, N., and N. Borenstein, “Multipurpose Internet Mail Extensions (MIME)—Part One: Format of Internet Message Bodies”, RFC 2045, November 1996), RFC 2046 (Freed, N., and N. Borenstein, “Multipurpose Internet Mail Extensions (MIME)—Part Two: Media Types”, RFC 2046, November 1996) and related RFCs. The MIME data consists of a header followed by a body. The header is encoded as a variable-length text string preceded by an 8-bit string length. The body is encoded as a variable-length type-specific octet stream preceded by a 16-bit size in big-endian format.

[0510] The basic top-level media types described in RFC 2046 include text, image, audio, video and application.

[0511] RFC 2425 (Howes, T., M. Smith and F. Dawson, “A MIME Content-Type for Directory Information”, RFC 2045, September 1998) and RFC 2426 (Dawson, F., and T. Howes, “vCard MIME Directory Profile”, RFC 2046, September 1998) describe a text subtype for directory information suitable, for example, for encoding contact information which might appear on a business card.

Encoding and Printing Considerations

[0512] The Print Engine Controller (PEC) (which is the subject of a number of pending US patent applications, including: Ser. Nos. 09/575,108; 10/727,162; 09/575,110; 09/607,985; Ser. Nos. 6,398,332; 6,394,573; 6,622,923) supports the encoding of two fixed (per-page) 2⁴-ary (15,7) Reed-Solomon codewords and four variable (per-tag) 2⁴-ary (15,7) Reed-Solomon codewords, although other numbers of codewords can be used for different schemes.

[0513] Furthermore, PEC supports the rendering of tags via a rectangular unit cell whose layout is constant (per page) but whose variable codeword data may vary from one unit cell to the next. PEC does not allow unit cells to overlap in the direction of page movement.

[0514] A unit cell compatible with PEC contains a single tag group consisting of four tags. The tag group contains a single A codeword unique to the tag group but replicated four times within the tag group, and four unique B codewords. These can be encoded using five of PEC's six supported variable codewords. The tag group also contains eight fixed C and D codewords. One of these can be encoded using the remaining one of PEC's variable codewords, two more can be encoded using PEC's two fixed codewords, and the remaining five can be encoded and pre-rendered into the Tag Format Structure (TFS) supplied to PEC.

[0515] PEC imposes a limit of 32 unique bit addresses per TFS row. The contents of the unit cell respect this limit. PEC also imposes a limit of 384 on the width of the TFS. The contents of the unit cell respect this limit.

[0516] Note that for a reasonable page size, the number of variable coordinate bits in the A codeword is modest, making encoding via a lookup table tractable. Encoding of the B codeword via a lookup table may also be possible. Note that since a Reed-Solomon code is systematic, only the redundancy data needs to appear in the lookup table.

Imaging and Decoding Considerations

[0517] The minimum imaging field of view required to guarantee acquisition of an entire tag has a diameter of 39.6 s, i.e.
(2×(12+2))√{square root over (2)}s
allowing for arbitrary alignment between the surface coding and the field of view. Given a macrodot spacing of 143 μm, this gives a required field of view of 5.7 mm.

[0518] Table 10 gives pitch ranges achievable for the present surface coding for different sampling rates, assuming an image sensor size of 128 pixels.

TABLE 10
Pitch ranges achievable for present surface coding for different
sampling rates, computed using Optimize Hyperlabel Optics;
dot pitch = 1600 dpi, macrodot pitch = 9 dots, viewing
distance = 30 mm, nib-to-FOV separation = 1 mm,
image sensor size = 128 pixels
	sampling rate	pitch range
	2	−40 to +49
	2.5	−27 to +36
	3	−10 to +18

[0519] For the surface coding of the first example, the corresponding decoding sequence is as follows:

• • [0520] locate targets of complete tag
  • [0521] infer perspective transform from targets
  • [0522] sample and decode any one of tag's four codewords
  • [0523] determine codeword type and hence tag orientation
  • [0524] sample and decode required local (A and B) codewords
  • [0525] codeword redundancy is only 12 bits, so only detect errors
  • [0526] on decode error flag bad position sample
  • [0527] determine tag x-y location, with reference to tag orientation
  • [0528] infer 3D tag transform from oriented targets
  • [0529] determine nib x-y location from tag x-y location and 3D transform
  • [0530] determine active area status of nib location with reference to active area map
  • [0531] generate local feedback based on nib active area status
  • [0532] determine tag type from A codeword
  • [0533] sample and decode required global (C and D) codewords (modulo window alignment, with reference to tag type)
  • [0534] although codeword redundancy is only 12 bits, correct errors; subsequent CRC verification will detect erroneous error correction
  • [0535] verify tag group data CRC
  • [0536] on decode error flag bad region ID sample
  • [0537] determine encoding type, and reject unknown encoding
  • [0538] determine region flags
  • [0539] determine region ID
  • [0540] encode region ID, nib x-y location, nib active area status in digital ink
  • [0541] route digital ink based on region flags

[0542] Note that region ID decoding need not occur at the same rate as position decoding.

[0543] Note that decoding of a codeword can be avoided if the codeword is found to be identical to an already-known good codeword.

[0544] For the surface coding of the alternative first example, the corresponding decoding sequence is as follows:

• • [0545] locate targets of complete tag
  • [0546] infer perspective transform from targets
  • [0547] sample cyclic position code
  • [0548] decode cyclic position code
  • [0549] determine orientation from cyclic position code
  • [0550] sample and decode local Reed-Solomon codeword
  • [0551] determine tag x-y location
  • [0552] infer 3D tag transform from oriented targets
  • [0553] determine nib x-y location from tag x-y location and 3D transform
  • [0554] determine active area status of nib location with reference to active area map
  • [0555] generate local feedback based on nib active area status
  • [0556] determine tag type
  • [0557] sample distributed Reed-Solomon codewords (modulo window alignment, with reference to tag type)
  • [0558] decode distributed Reed-Solomon codewords
  • [0559] verify tag group data CRC
  • [0560] on decode error flag bad region ID sample
  • [0561] determine encoding type, and reject unknown encoding
  • [0562] determine region flags
  • [0563] determine region ID
  • [0564] encode region ID, nib x-y location, nib active area status in digital ink
  • [0565] route digital ink based on region flags

[0566] Region ID decoding need not occur at the same rate as position decoding and decoding of a codeword can be avoided if the codeword is found to be identical to an already-known good codeword.

[0567] If the high-order coordinate width is non-zero, then special care must be taken on boundaries between tags where the low-order x or y coordinate wraps, otherwise codeword errors may be introduced. If wrapping is detected from the low-order x or y coordinate (i.e. it contains all zero bits or all one bits), then the corresponding high-order coordinate can be adjusted before codeword decoding. In the absence of genuine symbol errors in the high-order coordinate, this will prevent the inadvertent introduction of codeword errors.

Expanded Tag

[0568] The tag can be expanded to increase its data capacity by adding additional bands of symbols about its circumference. This appendix describes an expanded tag with one additional band of symbols. While the tag described in the main part of the document has a raw capacity of 36 symbols, the expanded tag has a raw capacity of 60 symbols.

[0569] The capacity of the expanded tag is precisely sufficient to allow the inclusion of a complete 160-bit digital signature in each tag group. This allows complete digital signature verification on a “single-click” interaction with the surface coding.

Tag Structure

[0570] FIG. 39 shows the structure of a complete (P type) expanded tag. Apart from the additional band of symbols and the related change in the positions of the targets, it has a similar physical structure to the tag described earlier.

[0571] In the expanded tag the macrodot spacing^S has a nominal value of 111 μm, based on 7 dots printed at a pitch of 1600 dots per inch.

[0572] A macrodot is nominally circular with a nominal diameter of (3/7)s.

[0573] A target is nominally circular with a nominal diameter of (10/7)s.

[0574] The expanded tag, like the tag described earlier, also participates in a tag group, and each expanded tag has one of the three possible tag types P, Q and R.

[0575] The expanded tag, like the tag described earlier, contains an orientation-indicating cyclic position code.

Local Codeword

[0576] The expanded tag locally contains one complete codeword which is used to encode information unique to the tag. The codeword is of a punctured 2⁴-ary (12,7) Reed-Solomon code. The tag therefore encodes up to 28 bits of information unique to the tag.

[0577] The layout of the local codeword is shown in FIG. 40.

Distributed Codewords

[0578] The expanded tag contains fragments of twelve codewords, labelled B through M, which are distributed across three adjacent tags and which are used to encode information common to a set of contiguous tags. Each codeword is of a punctured 2⁴-ary (12,7) Reed-Solomon code. Any three adjacent tags therefore together encode up to 336 bits of information common to a set of contiguous tags.

[0579] The layout of the first four fragments of the six codewords B through G in tag type P is shown in FIG. 41. The layout in the other tag types follows the layout in tag type P, with symbols 4 through 7 in tag type Q, and fragments 8 through 11 in tag type Q.

[0580] The layout of the first four fragments of the six codewords H through M in tag type P is shown in FIG. 42. The layout in the other tag types follows the layout in tag type P, with symbols 4 through 7 in tag type Q, and fragments 8 through 11 in tag type Q.

[0581] As shown earlier in FIG. 37, the tiling guarantees the any set of three adjacent tags contains one tag of each type, and therefore contains a complete set of distributed codewords. The tag type, used to determine the registration of the distributed codewords with respect to a particular set of adjacent tags, is inferred from the x-y coordinate encoded in the local codeword of each tag.

Tag Coordinate Space

[0582] The tag coordinate space encoded in the expanded tag is identical to that encoded in the tag described earlier, with the exception that tag units are different (due both to the change in tag structure and the change in macrodot spacing).

[0583] Horizontal and vertical tag units, based on center-to-center tag tag spacings, are given by: $u_x=5\left(2\sqrt{3}s\right)+2d\cong 17.6s$ $u_y=7.5\left(2s\right)+2\left(d\frac{\sqrt{3}}{2}\right)\cong 15.2s$
where d is the inter-segment spacing given by
d=(1−√{square root over (3)}/2)s
Tag Information Content

[0584] Table 11 defines the information fields embedded in the expanded tag surface coding. Table 12 defines how these fields map to codewords.

TABLE 11
Field definitions
Field	width	description
per tag
x coordinate	10	The unsigned x coordinate of the tag - allows a maximum
		x coordinate value of approximately 2.0 m (based on EQ
		8).
y coordinate	10	The unsigned y coordinate of the tag - allows a maximum
		y coordinate value of approximately 1.7 m (based on EQ
		9)
active area flag	1	A flag indicating whether the tag is a member of an
		active area. b′1′ indicates membership.
active area map flag	1	A flag indicating whether an active area map is present.
		b′1′ indicates the presence of a map (see next field). If
		the map is absent then the value of each map entry is
		derived from the active area flag (see previous field).
active area map	6	A map of which of the tag's immediate six neighbours
		are members of an active area. b′1′ indicates
		membership - FIG. 37 indicates the bit ordering of the
		map
data fragment	6	A fragment of an embedded data stream. Only present if
		the active area map is absent
per tag group
encoding format	12	The format of the encoding.
		Refer to Table 5 for values.
macrodot spacing adjustment	16	The difference between the actual macrodot spacing and
		the nominal macrodot spacing, in nm units, in sign-
		magnitude format - the nominal macrodot spacing is
		111125 nm (based on 1600 dpi and 7 dots per macrodot
region flags	12	Flags controlling the interpretation and routing of region-
		related information.
		Refer to Table 5 for values.
region ID	112	The ID of the region containing the tags.
Signature	160	A digital signature of the region ID.
CRC	16	A CRC (CCITT CRC-16) of tag group data.

[0585]

TABLE 12
Mapping of fields to codewords
	codeword	field	field
codeword	bits	width	bits	field
A	9:0	10	all	x coordinate
	19:10	10	all	y coordinate
	20	1	all	active area flag
	21	1	all	active area map flag
	27:22	6	all	active area map
	27:22	6	all	data fragment
B	11:0	12	all	encoding format
	27:12	16	all	macrodot spacing
				adjustment
C	11:0	12	all	region flags
	27:12	16	27:12	region ID
D	27:0	28	55:28
E	27:0	28	83:56
F	27:0	28	111:84
G	11:0	12	11:0
	27:12	16	all	CRC
H	27:0	28	27:0	signature
I	27:0	28	55:28
J	27:0	28	83:56
K	27:0	28	111:84
L	27:0	28	139:112
M	19:0	20	159:140
	27:20	8	all	unused

Encoding and Printing Considerations

[0586] The tag group unit cell of the expanded tag only respects PEC's TFS width limit if the macrodot spacing is reduced from 9 to 7 dots, as reflected in the macrodot spacing^S of 111 μm.

Imaging and Decoding Considerations

[0587] The minimum imaging field of view required to guarantee acquisition of an entire expanded tag has a diameter of 44 s i.e.
2(1+8+2)₂s)
allowing for arbitrary alignment between the surface coding and the field of view. Given a macrodot spacing of 111 μm this gives a required field of view of approximately 4.0 mm.
Surface Coding Security
Security Requirements
Item security can be defined to have two related purposes:

• • [0588] to allow authentication of an item
  • [0589] to prevent forgery of an item

[0590] The greater the difficulty of forgery, the greater the trustworthiness of authentication. When an item is coded, Hyperlabel surface coding security has two corresponding purposes:

• • [0591] to allow authentication of a coded item
  • [0592] to prevent forgery of a coded item with a novel item ID

[0593] If a user is able to determine the authenticity of the surface coding of an item, then the user may be able to make an informed decision about the likely authenticity of the item.

[0594] If it is intractable to forge the surface coding for a novel ID, then the only tractable way of forging an item with an authentic surface coding is to duplicate the surface coding of an existing item (and hence its ID). If the user is able to determine by other means that the ID of an item is likely to be unique, then the user may assume that the item is authentic.

[0595] Since the Hyperlabel surface coding allows meaningful interaction between a sensing device and a coded surface during a purely local interaction, it is desirable for the surface coding to support authentication during a similarly local interaction, i.e. without requiring an increase in the size of the sensing device field of view.

[0596] Since no a priori relationship exists between creators of authentic coded items and users potentially wishing to authenticate such items, it is undesirable to require a trust relationship between creators and users. For example, it is undesirable to require that creators share secret signature keys with users.

[0597] It is reasonable for many users to rely on online access to an authenticator trusted by a creator for the purposes of authenticating items. Conversely, it is desirable to allow authentication to take place in the absence of online access.

Security Discussion

[0598] As described above, authentication relies on verifying the correspondence between data and a signature of that data. The greater the difficulty in forging a signature, the greater the trustworthiness of signature-based authentication.

[0599] The item ID is unique and therefore provides a basis for a signature. If online authentication access is assumed, then the signature may simply be a random number associated with the item ID in an authentication database accessible to the trusted online authenticator. The random number may be generated by any suitable method, such as via a deterministic (pseudo-random) algorithm, or via a stochastic physical process. A keyed hash or encrypted hash may be preferable to a random number since it requires no additional space in the authentication database. However, a random signature of the same length as a keyed signature is more secure than the keyed signature since it is not susceptible to key attacks. Equivalently, a shorter random signature confers the same security as a longer keyed signature.

[0600] In the limit case no signature is actually required, since the mere presence of the item ID in the database indicates authenticity. However, the use of a signature limits a forger to forging items he has actually sighted.

[0601] To prevent forgery of a signature for an unsighted ID, the signature must be large enough to make exhaustive search via repeated accesses to the online authenticator intractable. If the signature is generated using a key rather than randomly, then its length must also be large enough to prevent the forger from deducing the key from known ID-signature pairs. Signatures of a few hundred bits are considered secure, whether generated using private or secret keys.

[0602] While it may be practical to include a reasonably secure random signature in a tag (or local tag group), particularly if the length of the ID is reduced to provide more space for the signature, it may be impractical to include a secure ID-derived signature in a tag. To support a secure ID-derived signature, we can instead distribute fragments of the signature across multiple tags. If each fragment can be verified in isolation against the ID, then the goal of supporting authentication without increasing the sensing device field of view is achieved. The security of the signature can still derive from the full length of the signature rather than from the length of a fragment, since a forger cannot predict which fragment a user will randomly choose to verify. A trusted authenticator can always perform fragment verification since they have access to the key and/or the full stored signature, so fragment verification is always possible when online access to a trusted authenticator is available.

[0603] Fragment verification requires that we prevent brute force attacks on individual fragments, otherwise a forger can determine the entire signature by attacking each fragment in turn. A brute force attack can be prevented by throttling the authenticator on a per-ID basis. However, if fragments are short, then extreme throttling is required. As an alternative to throttling the authenticator, the authenticator can instead enforce a limit on the number of verification requests it is willing to respond to for a given fragment number. Even if the limit is made quite small, it is unlikely that a normal user will exhaust it for a given fragment, since there will be many fragments available and the actual fragment chosen by the user can vary. Even a limit of one can be practical. More generally, the limit should be proportional to the size of the fragment, i.e. the smaller the fragment the smaller the limit. Thus the experience of the user would be somewhat invariant of fragment size. Both throttling and enforcing fragment verification limits imply serialisation of requests to the authenticator. A fragment verification limit need only be imposed once verification fails, i.e. an unlimited number of successful verifications can occur before the first failure. Enforcing fragment verification limits further requires the authenticator to maintain a per-fragment count of satisfied verification requests.

[0604] A brute force attack can also be prevented by concatenating the fragment with a random signature encoded in the tag. While the random signature can be thought of as protecting the fragment, the fragment can also be thought of as simply increasing the length of the random signature and hence increasing its security. A fragment verification limit can make verification subject to a denial of service attack, where an attacker deliberately exceeds the limit with invalid verification request in order to prevent further verification of the item ID in question. This can be prevented by only enforcing the fragment verification limit for a fragment when the accompanying random signature is correct.

[0605] Fragment verification may be made more secure by requiring the verification of a minimum number of fragments simultaneously.

[0606] Fragment verification requires fragment identification. Fragments may be explicitly numbered, or may more economically be identified by the two-dimensional coordinate of their tag, modulo the repetition of the signature across a continuous tiling of tags.

[0607] The limited length of the ID itself introduces a further vulnerability. Ideally it should be at least a few hundred bits. In the netpage surface coding scheme it is 96 bits or less. To overcome this the ID may be padded. For this to be effective the padding must be variable, i.e. it must vary from one ID to the next. Ideally the padding is simply a random number, and must then be stored in the authentication database indexed by ID. If the padding is deterministically generated from the ID then it is worthless.

[0608] Offline authentication of secret-key signatures requires the use of a trusted offline authentication device. The QA chip (which is the subject of a number of pending US patent applications, including Ser Nos. 09/112,763; 09/112,762; 09/112,737; 09/112,761; 09/113,223) provides the basis for such a device, although of limited capacity. The QA chip can be programmed to verify a signature using a secret key securely held in its internal memory. In this scenario, however, it is impractical to support per-ID padding, and it is impractical even to support more than a very few secret keys. Furthermore, a QA chip programmed in this manner is susceptible to a chosen-message attack. These constraints limit the applicability of a QA-chip-based trusted offline authentication device to niche applications.

[0609] In general, despite the claimed security of any particular trusted offline authentication device, creators of secure items are likely to be reluctant to entrust their secret signature keys to such devices, and this is again likely to limit the applicability of such devices to niche applications.

[0610] By contrast, offline authentication of public-key signatures (i.e. generated using the corresponding private keys) is highly practical. An offline authentication device utilising public keys can trivially hold any number of public keys, and may be designed to retrieve additional public keys on demand, via a transient online connection, when it encounters an ID for which it knows it has no corresponding public signature key. Untrusted offline authentication is likely to be attractive to most creators of secure items, since they are able to retain exclusive control of their private signature keys.

[0611] A disadvantage of offline authentication of a public-key signature is that the entire signature must be acquired from the coding, violating our desire to support authentication with a minimal field of view. A corresponding advantage of offline authentication of a public-key signature is that access to the ID padding is no longer required, since decryption of the signature using the public signature key generates both the ID and its padding, and the padding can then be ignored. A forger can not take advantage of the fact that the padding is ignored during offline authentication, since the padding is not ignored during online authentication.

[0612] Acquisition of an entire distributed signature is not particularly onerous. Any random or linear swipe of a hand-held sensing device across a coded surface allows it to quickly acquire all of the fragments of the signature. The sensing device can easily be programmed to signal the user when it has acquired a full set of fragments and has completed authentication. A scanning laser can also easily acquire all of the fragments of the signature. Both kinds of devices may be programmed to only perform authentication when the tags indicate the presence of a signature.

[0613] Note that a public-key signature may be authenticated online via any of its fragments in the same way as any signature, whether generated randomly or using a secret key. The trusted online authenticator may generate the signature on demand using the private key and ID padding, or may store the signature explicitly in the authentication database. The latter approach obviates the need to store the ID padding.

[0614] Note also that signature-based authentication may be used in place of fragment-based authentication even when online access to a trusted authenticator is available.

[0615] Table 13 provides a summary of which signature schemes are workable in light of the foregoing discussion.

TABLE 13
Summary of workable signature schemes
			online
encoding	acquisition	signature	authen-	offline
in tags	from tags	generation	tication	authentication
Local	full	random	ok	Impractical to
				store per ID
				information
		secret key	Signature too	Undesirable to
			short to be	store secret
			secure	keys
		private key	Signature too
			short to be
			secure
Distributed	fragment(s)	random	ok	impracticalb
		secret key	ok	impracticalc
		private key	ok	impracticalb
	full	random	ok	impracticalb
		secret key	ok	impracticalc
		private key	ok	ok

Security Specification

[0616] FIG. 43 shows an example item signature object model. An item has an ID (X) and other details (not shown). It optionally has a secret signature (Z). It also optionally has a public-key signature. The public-key signature records the signature (S) explicitly, and/or records the padding (P) used in conjunction with the ID to generate the signature. The public-key signature has an associated public-private key pair (K, L). The key pair is associated with a one or more ranges of item IDs.

[0617] Typically issuers of security documents and pharmaceuticals will utilise a range of IDs to identify a range of documents or the like. Following this, the issuer will then use these details to generate respective IDs for each item, or document to be marked.

[0618] Authentication of the product can then be performed online or offline by sensing the tag data encoded within the tag, and performing the authentication using a number of different mechanisms depending on the situation.

[0619] Examples of the processes involved will now be described for public and private key encryption respectively.

Authentication Based on Public-Key Signature

Setup per ID range:

• • [0620] generate public-private signature key pair (K, L)
  • [0621] store key pair (K, L) indexed by ID range
    Setup per ID:
  • [0622] generate ID padding (P)
  • [0623] retrieve private signature key (L) by ID (X)
  • [0624] generate signature (S) by encrypting ID (X) and padding (P) using private key (L):
  • [0625] S←E_L(X, P)
  • [0626] store signature (S) in database indexed by ID (X) (and/or store padding (P))
  • [0627] encode ID (X) in all tag groups
  • [0628] encode signature (S) across multiple tags in repeated fashion
    Online fragment-based authentication (user):
  • [0629] acquire ID (X) from tags
  • [0630] acquire position (x, y)_j and signature fragment (T_i) from tag
  • [0631] generate fragment number (i) from position (x, y)_i:
    • [0632] i←F[(x,y)_i]
  • [0633] look up trusted authenticator by ID (X)
  • [0634] transmit ID (X), fragment (S_i) and fragment number (i) to trusted authenticator
    Online fragment-based authentication (trusted authenticator):
  • [0635] receive ID (X), fragment (S_i) and fragment number (i) from user
  • [0636] retrieve signature (S) from database by ID (X) (or re-generate signature)
  • [0637] compare received fragment (T_i) with corresponding fragment of signature (S_i)
  • [0638] report authentication result to user
    Offline signature-based authentication (user):
  • [0639] acquire ID from tags (X)
  • [0640] acquire positions (x, y)_i and signature fragments (T_i) from tag
  • [0641] generate fragment numbers (i) from positions (x, y)_i:
    • [0642] i←F[(x, y)_i]
      • [0643] S←S₀|S₁| . . . |S_n-1
  • [0644] generate signature (S) from (n) fragments:
  • [0645] retrieve public signature key (K) by ID (X)
  • [0646] decrypt signature (S) using public key (K) to obtain ID (X′) and padding (P′):
  • [0647] X′|P′←D_K(S)
  • [0648] compare acquired ID (A) with decrypted ID (X′)
  • [0649] report authentication result to user
    Authentication Based on Secret-Key Signature
    Setup per ID:
  • [0650] generate secret (Z)
  • [0651] store secret (Z) in database indexed by ID (X)
  • [0652] encode ID (X) and secret (Z) in all tag groups
    Online secret-based authentication (user):
  • [0653] acquire ID (X) from tags
  • [0654] acquire secret (Z′) from tags
  • [0655] look up trusted authenticator by ID
  • [0656] transmit ID (X) and secret (Z′) to trusted authenticator
    Online secret-based authentication (trusted authenticator):
  • [0657] receive ID (X′) and secret (Z′) from user
  • [0658] retrieve secret (Z) from database by ID (X)
  • [0659] compared received secret (Z′) with secret (Z)
  • [0660] report authentication result to user
    As discussed earlier, secret-based authentication may be used in conjunction with fragment-based authentication.
    Cryptographic Algorithms

[0661] When the public-key signature is authenticated offline, the user's authentication device typically does not have access to the padding used when the signature was originally generated. The signature verification step must therefore decrypt the signature to allow the authentication device to compare the ID in the signature with the ID acquired from the tags. This precludes the use of algorithms which don't perform the signature verification step by decrypting the signature, such as the standard Digital Signature Algorithm U.S. Department of Commerce/National Institute of Standards and Technology, Digital Signature Standard (DSS), FIPS 186-2, 27 January 2000.

[0662] RSA encryption is described in:

• • [0663] Rivest, R. L., A. Shamir, and L. Adleman, “A Method for Obtaining Digital Signatures and Public-Key Cryptosystems”, Communications of the ACM, Vol. 21, No. 2, February 1978, pp. 120-126
  • [0664] Rivest, R. L., A. Shamir, and L. M. Adleman, “Cryptographic communications system and method”, U.S. Pat. No. 4,405,829, issued 20 Sep. 1983
  • [0665] RSA Laboratories, PKCS #1 v2.0: RSA Encryption Standard, Oct. 1, 1998

[0666] RSA provides a suitable public-key digital signature algorithm that decrypts the signature. RSA provides the basis for the ANSI X9.31 digital signature standard American National Standards Institute, ANSI X9.31-1998, Digital Signatures Using Reversible Public Key Cryptography for the Financial Services Industry (rDSA), Sep. 8, 1998. If no padding is used, then any public-key signature algorithm can be used.

[0667] In the Hyperlabel surface coding scheme the ID is 96 bits long or less. It is padded to 160 bits prior to being signed.

[0668] The padding is ideally generated using a truly random process, such as a quantum process [14,15], or by distilling randomness from random events Schneier, B., Applied Cryptography, Second Edition, John Wiley & Sons 1996.

[0669] In the Hyperlabel surface coding scheme the random signature, or secret, is 36 bits long or less. It is also ideally generated using a truly random process. If a longer random signature is required, then the length of the item ID in the surface coding can be reduced to provide additional space for the signature.

Security Tagging and Tracking

[0670] Currency, checks and other monetary documents can be tagged in order to detect currency counterfeiting and counter money laundering activities. The Hyperlabel tagged currency can be validated, and tracked through the monetary system. Hyperlabel tagged products such as pharmaceuticals can be tagged allowing items to be validated and tracked through the distribution and retail system.

[0671] A number of examples of the concepts of Hyperlabel security tagging and tracking referring specifically to bank notes and pharmaceuticals, however Hyperlabel tagging can equally be used to securely tag and track other products, for example, traveller's checks, demand deposits, passports, chemicals etc.

[0672] Hyperlabel tagging, with the netpage system, provides a mechanism for securely validating and tracking objects.

[0673] Hyperlabel tags on the surface of an object uniquely identify the object. Each Hyperlabel tag contains information including the object's unique ID, and the tag's location on the Hyperlabel tagged surface. A Hyperlabel tag also contains a signature fragment which can be used to authenticate the object. A scanning laser or image sensor can read the tags on any part of the object to identify the object, validate the object, and allow tracking of the object.

Currency Tagging

[0674] Currency may be tagged with Hyperlabels in order to detect counterfeiting and allow tracking of currency movement. Hyperlabel tags can be printed over the entire bank note surface or can be printed in a smaller region of the note. Hyperlabel tagging can be used in addition to other security features such as holograms, foil strips, colour-shifting inks etc. A scanning laser or image sensor can read the tags on any part of the note to validate each individual note.

[0675] A Hyperlabel currency tag identifies the note currency, issue country, and note denomination. It also identifies the note's serial number, the note side (i.e. front or back), and it may contain other information (for example, the exact printing works where the note was printed). There are two note IDs for each physical bank note—one for each side of the note.

[0676] Each time a note is scanned its location is recorded. This location information can be collected in a central database allowing analysis and identification of abnormal money movements and detection of counterfeit notes. For example, in the case of sophisticated forgeries where Hyperlabel dot patterns are exactly duplicated, there will be multiple copies of exactly forged notes (at a minimum, the original and the forgery). If multiple identical notes appear in different places at the same time, all but one of the notes must be a forgery. All can then be treated as suspect.

[0677] Hyperlabel currency tags can be read by any Hyperlabel scanner. These scanners can be incorporated into a variety of devices to facilitate authentication and tracking, for example, automated teller machines, currency counters, and vending machines. Scanners may also be incorporated into devices such as:

• • [0678] Currency counters
  • [0679] Automated teller machines
  • [0680] Cash registers
  • [0681] POS checkouts
  • [0682] Mobile phone with inbuilt scanner
  • [0683] Netpage pens
  • [0684] Vending machines
  • [0685] Hyperlabel Supermarket Checkout
  • [0686] Mobile Phone with Inbuilt Scanner
  • [0687] Handheld Validity Scanner

[0688] Such scanners are multi-purpose since they can also be used to scan Hyperlabel tagged consumer goods and printed materials. A small hand-held scanner may also be used to scan and validate currency. When a scanner scans a note it notifies the currency server of the note details, the current date and time, and the scanner location (if known). Optionally the scanner may also send the identity of the person making the cash transaction, if known. This information would be available in respect of bank transactions, currency exchanges and large cash transactions.

[0689] Currency tagging is discussed in further detail in copending patent application Ser. No. 11/041,651 (Docket number: HYN001US), Ser. No. 11/041,609 (Docket number: HYN002US), Ser. No. 11/041,652 (Docket number: HYN003US), Ser. No. 11/041,649 (Docket number: HYN004US) and Ser. No. 11/041,610 (Docket number: HYN005US), the contents of which are all incorporated herein by reference.

Pharmaceutical Tagging

[0690] Hyperlabel tags can be printed over the entire surface of the pharmaceutical packaging, or only on a smaller area of the packaging. A Hyperlabel pharmaceutical tag contains the item's product ID and a serial number, to uniquely identify an individual item. The product ID identifies the item's National Drug Code (NDC) number. The NDC number is allocated and administered by the FDA (U.S. Food and Drug Administration) for drugs and drug-related items and identifies the product and manufacturer. Alternatively the tag may contain another product ID code, such as the European International Article Numbering (EAN) code, or EPC etc.

[0691] The pharmaceutical ID can be read by a scanner and used to look up details of the item's lot number and expiry date. Alternatively the lot number and expiry date may be contained in the pharmaceutical tag to allow off-line retrieval of this information by any scanner. The pharmaceutical ID may also be used to access details such as dosage and administration information, drug interactions, precautions, contraindications, product warnings, recall information, place of manufacture etc.

[0692] Each time a pharmaceutical item is scanned its location is recorded. This location information can be collected in a central database allowing analysis and identification of abnormal product movements and detection of counterfeit pharmaceuticals.

[0693] Suitable scanners can include:

• • [0694] Cash registers
  • [0695] POS checkouts
  • [0696] Mobile phone with inbuilt scanner
  • [0697] Netpage pens
  • [0698] Vending machines
    Tracking

[0699] For the purpose of tracking and item validation the manufacturer, or other central authority, maintains a database which tracks the location and status of all items.

[0700] Hyperlabel scanners can be built into a variety of devices. Scanners may be fixed or mobile. A fixed scanner has a permanent, known location. A mobile scanner has no fixed location. A scanner may be on-line, i.e. have immediate access to the central database, or it may be off-line.

[0701] Scanners may be specific to a particular product application, such as a currency counter, or may be a generic Hyperlabel scanner. Hyperlabel scanners may be embedded in other multi-function devices, for example, a mobile phone or PDA.

[0702] A central database maintains up-to-date information on valid object IDs, an object ID hotlist (for all suspect object IDs), and a list of public keys corresponding to object IDs. The central server also maintains an object scanning history to track an object's movements. Each time an object is scanned, its timestamped location is recorded. If known, the details of the object owner may also be recorded. This information may be known particularly in the case of large financial transactions e.g. a large cash withdrawal from a bank. This object scanning history data can be used to detect illegal product movements, for example, the illegal import of a pharmaceutical. It can also be used to detect abnormal or suspicious product movements which may be indicative of product counterfeiting.

[0703] If an object is known to be stolen it can be immediately added to an object ID hotlist on the central server. This hotlist is automatically distributed to (or becomes accessible to) all on-line scanners, and will be downloaded to all off-line scanners on their next update. In this way the stolen status is automatically and rapidly disseminated to a huge number of outlets. Similarly, if an object is in any other way suspect it can be added to the hotlist so that its status is flagged to the person scanning the object.

[0704] An on-line scanner has instant access to the central server to allow checking of each object ID at the time of scanning. The object scanning history is also updated at the central server at the time the object is scanned.

[0705] An off-line scanner stores object status data internally to allow validation of a scanned object. The object status data includes valid ID range lists, an object ID hotlist, a public key list, and an object scanning history. Each time an object is scanned the details are recorded in the object scanning history. The object status data is downloaded from the central server, and the object scanning history is uploaded to the central server, each time the scanner connects.

[0706] A mobile scanner's location can be provided to the application by the scanner, if it is GPS-equipped. Alternatively the scanner's location can be provided by the network through which it communicates.

[0707] For example, if the hand-held scanner uses the mobile phone network, the scanner's location can be provided by the mobile phone network provider. There are a number of location technologies available. One is Assisted Global Positioning System (A-GPS). This requires a GPS-equipped handset, which receives positioning signals from GPS satellites. The phone network knows the approximate location of the handset (in this case the handset is also the scanner) from the nearest cell site. Based on this, the network tells the handset which GPS satellites to use in its position calculations. Another technology, which does not require the device to be GPS-equipped, is Uplink Time Difference of Arrival (U-TDOA). This determines the location of a wireless handset, using a form of triangulation, by comparing the time it takes a wireless handset's signal to reach several Location Measurement Units (LMUs) installed at the network's cell sites. The handset location is then calculated based on the differences in arrival times of the three (or more) signals.

Authentication

[0708] Each object ID has a signature. Limited space within the Hyperlabel tag structure makes it impractical to include a full cryptographic signature in a tag so signature fragments are distributed across multiple tags. A smaller random signature, or secret, can be included in a tag.

[0709] To avoid any vulnerability due to the limited length of the object ID, the object ID is padded, ideally with a random number. The padding is stored in an authentication database indexed by object ID. The authentication database may be managed by the manufacturer, or it may be managed by a third-party trusted authenticator.

[0710] Each Hyperlabel tag contains a signature fragment and each fragment (or a subset of fragments) can be verified, in isolation, against the object ID. The security of the signature still derives from the full length of the signature rather than from the length of the fragment, since a forger cannot predict which fragment a user will randomly choose to verify.

[0711] Fragment verification requires fragment identification. Fragments may be explicitly numbered, or may by identified by the two-dimensional coordinate of their tag, modulo the repetition of the signature across continuous tiling of tags.

[0712] Note that a trusted authenticator can always perform fragment verification, so fragment verification is always possible when on-line access to a trusted authenticator is available.

Establishing Authentication Database

[0713] Prior to allocating a new range of IDs, some setup tasks are required to establish the authentication database.

[0714] For each range of IDs a public-private signature key pair is generated and the key pair is stored in the authentication database, indexed by ID range.

[0715] For each object ID in the range the following setup is required:

• • [0716] generate ID padding and store in authentication database, indexed by object ID
  • [0717] retrieve private signature key by object ID
  • [0718] generate signature by encrypting object ID and padding, using private key
  • [0719] store signature in authentication database indexed by object ID, and/or store the padding, since the signature can be re-generated using the ID, padding and private key
  • [0720] encode the signature across multiple tags in repeated fashion

[0721] This data is required for the Hyperlabel tags therefore the authentication database must be established prior to, or at the time of, printing of the Hyperlabels.

[0722] Security issues are discussed in more detail above.

Off-Line Public-Key-Based Authentication

[0723] An off-line authentication device utilises public-key signatures. The authentication device holds a number of public keys. The device may, optionally, retrieve additional public keys on demand, via a transient on-line connection when it encounters an object ID for which it has no corresponding public key signature.

[0724] For off-line authentication, the entire signature is needed. The authentication device is swiped over the Hyperlabel tagged surface and a number of tags are read. From this, the object ID is acquired, as well as a number of signature fragments and their positions. The signature is then generated from these signature fragments. The public key is looked up, from the scanning device using the object ID. The signature is then decrypted using the public key, to give an object ID and padding. If the object ID obtained from the signature matches the object ID in the Hyperlabel tag then the object is considered authentic.

[0725] The off-line authentication method can also be used on-line, with the trusted authenticator playing the role of authenticator.

On-Line Public-Key-Based Authentication

[0726] An on-line authentication device uses a trusted authenticator to verify the authenticity of an object. For on-line authentication a single tag can be all that is required to perform authentication. The authentication device scans the object and acquires one or more tags. From this, the object ID is acquired, as well as at least one signature fragment and its position. The fragment number is generated from the fragment position. The appropriate trusted authenticator is looked up by the object ID. The object ID, signature fragment, and fragment number are sent to the trusted authenticator.

[0727] The trusted authenticator receives the data and retrieves the signature from the authentication database by object ID. This signature is compared with the supplied fragment, and the authentication result is reported to the user.

On-Line Secret-Based Authentication

[0728] Alternatively or additionally, if a random signature or secret is included in each tag (or tag group), then this can be verified with reference to a copy of the secret accessible to a trusted authenticator. Database setup then includes allocating a secret for each object, and storing it in the authentication database, indexed by object ID.

[0729] The authentication device scans the object and acquires one or more tags. From this, the object ID is acquired, as well as the secret. The appropriate trusted authenticator is looked up by the object ID. The object ID and secret are sent to the trusted authenticator.

[0730] The trusted authenticator receives the data and retrieves the secret from the authentication database by object ID. This secret is compared with the supplied secret, and the authentication result is reported to the user.

[0731] Secret-based authentication can be used in conjunction with on-line fragment-based authentication is discussed in more detail above.

Product Scanning Interactions

[0732] Product Scanning at a retailer is illustrated in FIG. 44. When a store operator scans a Hyperlabel tagged product the tag data is sent to the service terminal (A). The service terminal sends the transaction data to the store server (B).

[0733] The store server sends this data, along with the retailer details, to the manufacturer server (C). The Hyperlabel server knows which manufacturer server to send the message to from the object ID. On receipt of the input, the manufacturer server authenticates the object, if the manufacturer is the trusted authenticator. Alternatively the manufacturer server passes the data on to the authentication server to verify the object ID and signature (D). The authentication server sends the authentication result back to the manufacturer server (E). The manufacturer server checks the status of the object ID (against its valid ID lists and hotlist), and sends the response to the store server (F), which in turn send the result back the store service terminal (G). The store server could also communicate with the relevant authentication server directly.

[0734] The interaction detail for on-line product scanning at a retailer is shown in FIG. 45. The store operator scans the Hyperlabel tagged product. The scanner sends the scanner ID and tag data to the service terminal. The service terminal sends this data along with the terminal ID and scanner location to the store server. The store server then sends the request on to the manufacturer server, which performs authentication (either itself or via a third party authentication server) and determines the object status. The response is then sent back to the store server, and on to the operator service terminal.

[0735] The interaction detail for off-line product scanning at a retailer is shown in FIG. 46. The store operator scans the Hyperlabel tagged product. The scanner sends the scanner ID and tag data from multiple tags to the service terminal. The service terminal sends this data, along with the terminal ID and scanner location, to the store server. The store server then performs off-line authentication, as described in Section 3.4.2, and determines the object status through its cached hotlist, valid object ID lists, and public key list. The store server records the scan details in its internal object scanning history. The response is then sent back to the operator service terminal.

[0736] An alternative for off-line product scanner occurs where the scanner is a hand-held, stand-alone scanner. In this case the cached authentication data is stored within the scanner itself, and the scanner performs the validation internally. The object scanning history is also cached within the scanner. Periodically the scanner connects to the central database, uploads it's object scanning history, and downloads the latest public key list, object ID hotlist and valid ID range list. This connection may be automatic (and invisible to the user), or may be initiated by the user, for example, when the scanner is placed in a docking station/charger.

[0737] Product scanning with a netpage pen or Hyperlabel reader is illustrated in FIG. 47. When a user scans a Hyperlabel tagged item with their netpage pen, the input is sent to the netpage System, from the user's netpage pen, in the usual way (A). To scan a product rather than interact with it, the pen can be placed in a special mode. This is typically a one-shot mode, and can be initiated by tapping on a <scan> button printed on a netpage. Alternatively, the pen can have a user-operable button, which, when held down during a tap or swipe, tells the pen to treat the interaction as a product scan rather than a normal interaction. The tag data is transmitted from the pen to the user's netpage base station. The netpage base station may be the user's mobile phone or PDA, or it may be some other netpage device, such as a PC. The input is relayed to the Hyperlabel server (B) and then on to manufacturer server (C) in the usual way. On receipt of the input, the manufacturer server authenticates the object if the manufacturer is the trusted authenticator. Alternatively the manufacturer server passes the data on to the authentication server to verify the object ID and signature (D). The authentication server sends the authentication result back to the manufacturer server (E). The manufacturer server checks the status of the object ID (against its valid ID lists and hotlist), and sends the response to the Hyperlabel server (G). The Hyperlabel server, as part of the netpage system, can know the identity and devices of the user. The Hyperlabel server will relay the manufacturer server's response to the user's phone (G) or Web browsing device (H) as appropriate. If the user's netpage pen has LEDs then the Hyperlabel server can send a command to the user's pen to light the appropriate LED(s) (I,J).

[0738] The interaction detail for scanning with a netpage pen is shown in FIG. 48. The netpage pen clicks on the Hyperlabel tagged product. The netpage pen sends the pen id, the product's tag data and the pen's location to the Hyperlabel server. If the pen ID is not already associated with a scanner, the Hyperlabel server may create a new scanner record for the pen, or may use the pen ID as a scanner ID. The Hyperlabel server sends the scanner ID, tag data, and scanner location (if known) to the manufacturer server, which performs authentication (either itself or via a third party authentication server) and determines the object status. The response is then sent back to the Hyperlabel server, and on to the user's default Web browsing device.

Security Tagging and Tracking Object Model

[0739] The Security Tagging and Tracking object model revolves around Hyperlabel tags, object IDs, and signatures. FIG. 60 illustrates the management and organisation of these objects.

[0740] As shown in FIG. 49, a Hyperlabel tag comprises a tag type, object ID, two-dimensional position and a signature fragment. The tag type indicates whether this is a tag on a common object, or whether the tag is on a special type of object such as a currency note or a pharmaceutical product. A signature fragment has an optional fragment number which identifies the fragment's place within the full signature.

[0741] As described above, a product's unique item ID may be seen as a special kind of unique object ID. The Electronic Product Code (EPC) is one emerging standard for an item ID. An item ID typically consists of a product ID and a serial number. The product ID identifies a class of product, while the serial number identifies a particular instance of that class, i.e. an individual product item. The product ID in turn typically consists of a manufacturer number and a product class number. The best-known product ID is the EAN.UCC Universal Product Code (UPC) and its variants. The Item ID class diagram is shown in FIG. 50.

[0742] Currency notes are identified by a note ID. The note ID comprises note data and a serial number. The note data identifies the type of currency, the country of issue, the note denomination, the note side (front or back) and other currency-specific information. There are two note IDs for each physical bank note—one for each side of the printed note. The Note ID class diagram is shown in FIG. 51.

[0743] Pharmaceuticals are identified by a pharmaceutical ID. Typically the pharmaceutical ID will be an EPC. A pharmaceutical ID consists of a product ID and a serial number. The product ID in turn typically consists of a manufacturer number and a product class number. The best known product ID for pharmaceutical products is the National Drug Code (NDC), allocated and administered by the US Food and Drug Administration. The Pharmaceutical ID class diagram is shown in FIG. 52.

[0744] Object Description, ownership and aggregation class diagram is shown in FIG. 53. This is described in more detail above.

[0745] The Object Scanning History class diagram is shown in FIG. 54. An object has an object scanning history, recording each time the scanner scans an object. Each object scanned event comprises the scanner ID, the date and time of the scan, and the object status at the time of the scan, and the location of the scanner at the time the object was scanned. The object status may be valid, stolen, counterfeit suspected, etc. If known, the object owner details may also be recorded.

[0746] A scanner has a unique scanner ID, a network address, owner information and a status (e.g. on-line, off-line). A scanner is either a mobile scanner, whose location may vary, or a fixed scanner, whose location is known and constant. A scanner has a current location, comprising the location details and a timestamp. A scanner may be a netpage pen, in which case it will be associated with a netpage Pen record. If a scanner in off-line, it will keep an object scanning history, and will optionally store a public key list, a valid ID range list and an object ID hotlist. The scanner class diagram is shown in FIG. 55.

[0747] The manufacturer, or other central authority, maintains a number of Object ID Hot Lists, each with a unique list ID, and the time the list was last updated. Each hot list comprises a list of suspect object IDs, comprising the object ID, date, time, status (suspected counterfeit, stolen, etc.) and other information. The Object ID Hot List class diagram is shown in FIG. 56.

[0748] The manufacturer, or other central authority, maintains a list of valid ID ranges. Each valid object ID range entry in the list comprises the start object ID and end object ID (the valid ID range) and the time the entry was updated. The Valid ID Range List class diagram is shown in FIG. 57.

[0749] The manufacturer, or other central authority, maintains a public key list. The public key list consists of a number of entries identifying the public key for a range of Object IDs. Each valid object ID range entry comprises the update time for the entry, the start object ID for the range, the end object ID for the range, and the public key applicable to each object ID in the given range. The Public Key List class diagram is shown in FIG. 58.

[0750] Object authentication may be performed by the manufacturer, or by a third-party trusted authenticator. A trusted authenticator has an authenticator ID, name and details. A trusted authenticator holds a list of public-private key pairs, each associated with one or more ID ranges. This is a list of object ID ranges (identified by the start and end ID) and the corresponding public/private signature key pair. A trusted authenticator also holds a list of secret signatures, and a list of public-key signatures. Each public-key signature identifies the actual signature and/or the padding used to generate the signature. Each secret signature and public-key signature is associated by object ID with a unique object. The Trusted Authenticator class diagram is shown in FIG. 59.

Applications

[0751] It will be appreciated that Hyperlabel tags can be used with a range of objects, including, for example, items of manufacture, pharmaceutical items, currency notes, cheques, credit or debit cards, redeemable tickets, vouchers, coupons, lottery tickets instant win tickets, or identity cards or documents, such as a driver's licenses or passports.

[0752] The identity can include at least one of an Electronic Product Code (EPC), a National Drug Code (NDC) number, a serial number of a pharmaceutical item, a currency note attribute such as a value or the like, a cheque attribute or a card attribute such as card type, issuing institution, account number, issue date, expiry date or limit.

Advantages of Hyperlabel

[0753] Unlike 2D optical barcodes that are often difficult to read due to label damage and a direct ‘line-of-sight’ requirement needed for scanning, optically readable, but invisible, infrared Hyperlabel tags, are printed all over, or on a large section of a product label. Hyperlabel tags support line-of-sight omnidirectional reading. In practice, the Hyperlabel reader is designed to scan the scanning field from at least two substantially orthogonal directions. This helps the reader to avoid occlusions which may occur if a hand is holding an item. Hyperlabel tags also incorporate Reed-Solomon error correction methods to improve reliability.

[0754] A further advantage of Hyperlabels over barcodes is that they are unobtrusive to the customer as they do not use visible label space, and tag information is not restricted to only one section of a label. Hyperlabel tags are therefore easy to locate, easy to read, and enable accurate automatic scanning.

[0755] Hyperlabels are less promiscuous than RFID tags since they require line-of-sight for reading. This means that it will be difficult for customers to have their product scanned for information without their knowledge. Hyperlabels provide customers with the means to protect their privacy.

Hyperlabels as Interactive Web Pages

[0756] A distinctive and unique feature of Hyperlabel technology is that Hyperlabels provide the opportunity to design packaging labels as interactive ‘Web pages’—and thus make it possible for a whole new range of product-linked customer services to be introduced by the pharmaceutical industry.

[0757] When digital pen use becomes widespread, product graphics can be added to labels to indicate interactive areas and prompting customers to write or click using a Netpage pen. A digital Netpage pen can identify the x-y position on a label, and enable a link to be established between the information on the label, and a Web page on a server. The Netpage pen connects the customer to an Internet-based Hyperlabel Server through a companion device such as a mobile phone or computer.

[0758] Using a Netpage pen to interact with the label, customers can be offered additional information on drug use, risks and advice on potential interactions between drugs. It could also provide an opportunity for customers to register for participation in new drug trials, to enter promotions, to participate in Web chat sessions, or to receive ‘free’ samples. Web pages can be customised based on customer profiles, local area health data, or by using a range of product supply chain data such as geographic location.

[0759] Hyperlabels therefore make it possible for the pharmaceutical industry to extend the use of product labels and packaging to increase brand strength, and to establish closer links with customers. Thus, with Hyperlabels, the customer can become an integral part of the product supply chain, and supply chain data can be integrated with customer relationship management (CRM) or healthcare databases to improve the overall efficiency and level of service offered to customers.

Hyperlabel Tags Encoding Layout Data

[0760] A Hyperlabel tagged surface carries a continuous array of Hyperlabel tags. These typically encode the product item's unique identifier (e.g. EPC) and digital signature(s), as well as a two-dimensional coordinate grid.

[0761] A range of analog printing processes are used to produce labels and packaging, including gravure, letterpress, offset, flexographic, and digital. Some packaging is produced using multiple processes in sequence. For example, package graphics may be printed on a web-fed flexographic press, while batch and expiry information is digitally printed onto each finished package using laser marking or inkjet.

[0762] Hyperlabel tags may be printed digitally using an add-on digital printer, placed either before or after the colour press. The Hyperlabel digital add-on printer can utilise a Memjet printhead as described earlier, or any of a range of commercially-available laser and inkjet printheads such as from HP Indigo, Xaar, Xeikon, Agfa.dotrix, VideoJet, Mark Andy, etc. The Hyperlabel digital printer can be web-fed or sheet-fed according to the line to which it is added.

[0763] The add-on digital printer must be synchronised with the colour press to ensure registration between printed graphics and Hyperlabel tags. This can be achieved by conventional means, for example by generating an electronic signal in the colour press synchronised with the printing of an impression, and feeding that signal to the Hyperlabel printer. Alternatively, the Hyperlabel printer can optically detect printed fiducials produced by the colour press, as is sometimes used to synchronise die cutters with a colour press.

[0764] The Hyperlabel printer can be merely approximately synchronised with the colour press, and fine synchronisation can be achieved by measuring the actual registration achieved and recording a corresponding offset in the Netpage server database, as described elsewhere in relation to pre-tagged Netpage blanks. The measurement can take place while the packaging is still in the form of web or sheet media, or after being folded or applied to the product item. In the former case detection of the registration of the product graphics is still required, for example via fiducials as mentioned above. In the latter case registration of the product graphics is determined by virtue of the individual package passing along the line. This may be intrinsic in the design of the line, or may involve a photodetector to detect passage of the item. Detection of the Hyperlabel tag pattern uses a Hyperlabel reader in both cases.

[0765] Web or sheet media can be pre-printed (or printed in-line by an upstream digital Hyperlabel printer) with Hyperlabel tags which encode a continuous and large two-dimensional coordinate space and no explicit item identifiers. After passing through the colour press, each item's packaging will have a different range of coordinates. These can be detected as described above and recorded in the Netpage server database (and/or a product database) as being associated with the item and its item identifier. When a Hyperlabel tag on a particular item is subsequently read, its coordinate can be translated into an item identifier by querying the Netpage server (or product server).

[0766] A digital printhead can be adapted to print both product graphics and Hyperlabel tags, as described earlier in relation to Memjet digital printheads. Other digital printheads can be similarly adapted through the provision for an extra, infrared, ink channel.

[0767] As an alternative to digitally printing Hyperlabel tags, Hyperlabel tags can be printed using an analog process such as gravure, letterpress, offset or flexographic, for example on the same colour press used to print product graphics. A colour press is adapted to print Hyperlabel tags through the provision of an extra, infrared, ink channel; i.e. through the provision of an extra plate which bears the image of the Hyperlabel tags. The Hyperlabel plate can be produced by conventional means, such as computer to film (CtF) or direct computer to plate (CtP).

[0768] Note that although Hyperlabel tags are ideally printed using an invisible ink such as infrared ink, they can also be printed using a visible ink such as a coloured, black or gray ink. And although Hyperlabel tags are ideally printed over the entire product package, they can also be printed selectively in specific areas. And although Hyperlabel tags are ideally position-indicating, they can also be object-indicating, as described elsewhere.

[0769] If Hyperlabel tags are printed using an analog press, then it is impractical to provide each product item package with a unique serial number. However, the Hyperlabel tags can still encode the product identifier portion of the item identifier and the usual two-dimensional coordinate grid. In addition, the tags must encode a unique layout number which identifies the particular graphic (and interactive) layout of the package. The Hyperlabel tags also encode a flag which allows any Hyperlabel reader to determine that the tags encode a layout number rather than a serial number. The layout number only needs to be unique for different layouts associated with the same product identifier. It forms a unique layout identifier when paired with a product identifier, as shown in FIG. 61. The layout number changes precisely when new plates are produced for a new graphic package design, such as for a particular promotion or a particular geographic region. CtP makes frequent layout changes particularly convenient. Analog-printed Hyperlabel tags can thus encode a layout identifier rather than an item identifier, as shown in FIG. 62. During a subsequent interaction with a product item via a Hyperlabel reader, the layout identifier is used to retrieve the corresponding layout to allow the interaction to be interpreted in the usual way. For convenience we refer to such Hyperlabel tags as “layout-indicating” (to distinguish then from item-indicating Hyperlabel tags), and the data sent from the Hyperlabel reader to the Netpage server as “layout data”.

[0770] It is convenient to encode a product identifier in the layout identifier, since it allows a Hyperlabel reader to identify the product. However, it is also possible to encode a pure layout identifier in Hyperlabel tags which identifies the layout but does not directly identify the product. Equivalently, it is possible to encode a pure coordinate grid in the Hyperlabel tags and use the range of the coordinates to identify the corresponding layout. Thus all product items sharing the same graphic package layout would share the same coordinate grid range, and a change in layout would result in a change in coordinate grid range. The equivalence of a pure coordinate grid and a coordinate grid coupled with an item or layout identifier is discussed in the cross-referenced applications.

[0771] Layout-indicating Hyperlabel tags can confer interactivity in the usual way via the layout identifier and the coordinate grid that they encode, and product identification (but not product item identification) via the product identifier they encode.

[0772] Identification of individual product items is still important. It confers the various supply chain benefits discussed at length elsewhere, and plays a role in various interactive scenarios. For example, some product promotions may ideally be single-use, such as entering a competition or redeeming a token.

[0773] In addition, item-level identification, coupled with a digital signature unique to the item, allows product item authentication. In the following discussion, item-indicating Hyperlabel tags typically carry the digital signature(s) of the item in the usual way.

Location-Indicating Tags in Conjunction with Alternative Item Identifiers

[0774] Item-level identification can be provided in a variety of ways in conjunction with location-indicating or layout-indicating Hyperlabel tags. For example, location- or layout-indicating tags can be printed over the whole package, while item-indicating tags can be printed in only a small area. This has the benefit that the corresponding digital Hyperlabel printer can be relatively small, since it is no longer required to print tags across the full width of a web or sheet, but only onto a small area of each package. Digital printers for printing batch and expiry information, as well as for printing item-level indicia such as two-dimensional barcodes, are already part of conventional packaging workflows. A small-area digital Hyperlabel printer is can be incorporated in a similar place in such packaging workflows.

[0775] Item-level identification may be provided using a conventional radio-frequency identification (RFID) tag 210 or a linear or two-dimensional barcode 211 (FIGS. 67 and 68). Even if such carriers are present on a package, it can be convenient to also provide item-indicating Hyperlabel tags 4 in a small area, since these are readable by a standard Hyperlabel reader. Any Hyperlabel hyperlink which requires item-level identification, such as competition entry, token redemption or item authentication, can be implemented in the item-indicating Hyperlabel area. Alternatively, the user can be prompted to click in the item-indicating Hyperlabel area to identify the item, after invoking a single-use hyperlink elsewhere on the product where only layout-indicating tags are present.

[0776] If the item-level identification carrier is an RFID tag 210, then the Hyperlabel reader 101 can incorporate an RFID tag reader to allow it to obtain the item identifier from the RFID tag 210 at the same time as it reads location- or layout-indicating Hyperlabel tags 4. Having read the data contained in the Hyperlabel tag(s) 4 and the RFID tag 210, the Hyperlabel reader sends “indicating data”, which identifies the item ID and the position of the reader, to the Netpage server. In the case that the Hyperlabel tags 4 are location-indicating tags, the Netpage server can identify the layout from the item ID contained in the indicating data. Thus a Hyperlabel hyperlink requiring item-level identification can be implemented via a combination of location- or layout-indicating Hyperlabel tags 4 and an RFID tag 210. Accordingly, the Hyperlabel reader 101 may comprises an optical sensor for sensing the Hyperlabel tags 4, an RFID transceiver for sensing the RFID tag, a processor for generating the indicating data and means for communicating with the Netpage server (e.g. by wireless or wired communication)

[0777] Equivalently, a device already enabled with an RFID reader to provide gross interactivity with an RFID-tagged object or surface can be augmented with a Hyperlabel reader to allow it to support much more fine-grained interactivity with an RFID- and Hyperlabel-tagged object or surface.

[0778] If the item-level identification carrier is a visible barcode 211, then invisible item-indicating Hyperlabel tags 4 can be provided in the same area as the barcode. This allows a user of a Hyperlabel reader 101 to click on the barcode to obtain the item identifier, even though the Hyperlabel reader 101 may be unable to read the (arbitrarily large) visible barcode. Alternatively or additionally, item-indicating tags can be printed adjacent to the barcode using the same visible ink as the barcode, to eliminate the need for a separate Hyperlabel ink channel. A Hyperlabel reader 101 can also be augmented to allow it to read conventional barcodes.

[0779] An RFID tag or barcode can encode the same item identifier and digital signature(s) as an item-indicating Hyperlabel tag.

[0780] Rather than encoding an item identifier explicitly in an RFID tag 210, barcode 211 or Hyperlabel tag 4, a random pattern can be printed and characterised to serve both as an item identifier and as a digital signature. The random pattern, or at least a portion thereof, serves as a “fingerprint” for the object.

[0781] In US Patent Application Number 20050045055 (“Security Printing Method” filed 28 August 2003), the contents of which is incorporated herein by reference, Gelbart discusses the addition of powder taggants during printing for the purpose of subsequent authentication. As discussed elsewhere, both the presence of such a taggant and the exact random pattern formed by the taggant can be used as the basis for authentication and possibly identification.

[0782] When the random pattern formed by the taggant is used as the basis for authentication, the pattern is measured and recorded during product manufacture or packaging, and is measured and verified, with reference to the earlier recording, during subsequent authentication. The random pattern may cover the entire product surface or a subset thereof. The recorded reference data (reference fingerprints) derived from the pattern may cover the entire pattern or a subset thereof. The verification data (or fingerprint data) derived from the pattern during authentication typically relates to only a small area (e.g. one fingerprint) of the pattern. It is therefore necessary to know which area of the pattern is being verified, so that the verification data can be compared with the correct subset of the reference data. In some systems this relies on detecting other surface features, such as text or line art, and using such features as fiducials. Since such features are typically not unique, this approach may require guidance from a human operator.

[0783] Hyperlabel tags 4, since they encode a two-dimensional coordinate grid, provide a unique set of fiducials against which both reference data and verification data can be registered. This increases the reliability of authentication, and eliminates the need for human guidance. The taggant may be mixed with either the infrared ink used to print the Hyperlabels, or it may be mixed with the colored inks used to print graphical user information. In FIG. 69, the ink used to print the word ‘TEA’ contains a randomly dispersed taggant. Alternatively, if the taggant is applied by mixing it with an infrared ink, then the high density and (typical) full coverage of the Hyperlabel tag pattern 4 ensures that the taggant is also densely present on the entire tagged surface.

[0784] Although the random pattern formed by the taggant can be measured across the entire tagged surface, at a minimum it can be measured within a defined region. This region can be graphically delineated to indicate to a user that this is where item-level identification and/or authentication is available.

[0785] The random pattern can be characterised for each product package as it passes through the packaging line, either while the packaging is still on the web or sheet, or after the individual package is folded or filled. At this stage the spatial nature of the random pattern is analysed and recorded, either as a set of spatial features or as a hash of such spatial features. For example, each detected feature in the random pattern can be assigned a quantised two-dimensional coordinate within the Hyperlabel coordinate system, and the set of quantised coordinates can be hashed to produce a single compact number. Verification then consists of generating the equivalent hash and comparing it with the reference hash.

[0786] A Hyperlabel reader 101 may incorporate a reader for reading the random pattern formed by the taggant. If the taggant is read optically, then the Hyperlabel reader's image sensor can be used to read the taggant pattern. If the taggant uses a different wavelength to the Hyperlabel tag pattern, then the Hyperlabel reader 101 can alternate between activating LEDs matched to the wavelength of the Hyperlabel tag pattern, and LEDs matched to the wavelength of the taggant. If the taggant needs to be imaged with a greater magnification than the Hyperlabel tag pattern, then the Hyperlabel reader can either always image at the greater magnification, and subsample when processing Hyperlabel tag images, or it can incorporate dual optical paths, optionally using a beam splitter to allow a single external aperture.

[0787] If no explicit item-level identifier is available (e.g. from an RFID tag 210, barcode 211 or Hyperlabel tag 4), then the reference data (e.g. hash) can also serve as an item identifier. The product item is assigned a standard item identifier at time of manufacture, the standard item identifier is stored in the product database keyed by the reference data, and the standard item identifier can subsequently be recovered using the verification data (e.g. hash) as a key to look up the database, either for identification or verification purposes.

[0788] In the presence of layout-indicating Hyperlabel tags which encode a product identifier, the random pattern only needs to map to a serial number, not an entire item identifier.

[0789] A serialised product item carries a unique item identifier which typically consists of a product identifier and a serial number. The item ID may be carried by the product item in a number of ways. For example, it may be carried in a linear or two-dimensional barcode 211, a RFID tag 210, or a Hyperlabel tag pattern 4. The product item may also carry a digital signature associated with the item ID which allows a reader to verify with a certain degree of certainty that the item is authentic.

Verification of Product Authenticity

[0790] We wish to allow people who purchase and use a product item to verify its authenticity. They may use a dedicated device to read and verify the item ID and digital signature carried by an item, or they may use a more general-purpose device such as a mobile phone, suitably-enabled with a reader. The reader is matched to the carrier(s) used by the product item to carry the item ID and digital signature. For example, it may be an optical reader for linear or two-dimensional barcodes, an RF reader for RFID tags, or an optical reader for Hyperlabel tags.

[0791] FIG. 63 shows the basic interaction between a product item, reader device and product service during product authentication. The reader reads the item ID and at least a partial digital signature from the item. The reader then queries a name service using item ID to identify a product service for the item. The product service is typically run by or on behalf of the manufacturer of the item, and records information about product items such as product descriptions, digital signatures and/or keys used to generate digital signatures, and pedigree information. The reader queries the product service using the item ID and (partial) digital signature to authenticate the product item. As described earlier, the product service authenticates the (partial) digital signature with respect to the item ID, and responds to the reader with an authentication result message which indicates whether the item is authentic or not. The authentication result message may also identify the object identity. For further security, the reader may additionally generate a nonce which it sends to the product service and the authentication result message may include this nonce.

[0792] Note that the product service may in fact be composed of a number of services run by a number of different entities. For example, the manufacturer may run a basic product service which provides product descriptions, but may entrust the product authentication function to a third-party authenticator.

[0793] The reader incorporates a mechanism for indicating the result of the authentication to the user. For example, the indicating mechanism can produce audible, visible or tactile output. In the limit case the indicating mechanism may simply provide a binary pass or fail indication, such as via a beep or buzz, a green or red LED, or a short or long vibration.

[0794] Note that the reader device may consist of a collection of devices. For example, the reader itself may be separate from the device used to communicate with services on the network, which may itself be separate from the device which incorporates the indicating mechanism.

[0795] However, a counterfeiter could foil a binary pass/fail indicator by tagging a counterfeit product item with a valid item ID and digital signature harvested from a different product class and possibly manufacturer. To prevent this exploit, the reader must confirm the manufacturer and/or product class of the item to the user to allow the user to correlate this information with the actual product item.

[0796] Again, the indicating mechanism can produce audible or visible output, but structured to convey the manufacturer and/or product class of the product item to the user. For example, the indicating mechanism can play back a spoken or synthesised audio message via a speaker, or show text and/or imagery on a display.

[0797] However, a counterfeiter could foil this system by tagging a counterfeit product item with a valid item ID and digital signature administered by the counterfeiter, and spoofing the manufacturer and/or product class of the item to mislead the user into believing the item is authentic. To prevent this exploit, the counterfeiter must be prevented from spoofing the name of the manufacturer and/or the name of a product class.

[0798] FIG. 64 shows a more secure interaction between a product item, reader device and product service during product authentication, enhanced to involve a trusted certificate authority (CA). In the enhanced protocol the authentication result message from the product service to the reader is signed by the product service. The reader can verify the authenticity of the names of the manufacturer and product class as follows. The authentication result message contains the manufacturer identifier. The reader identifies a CA for the manufacturer, and queries the CA using the manufacturer ID to obtain the manufacturer's certificate. The certificate contains a public key which the reader can use to authenticate the message, and the name of the manufacturer suitable for playback or display. The certificate is signed by the CA, and the CA guarantees not to sign a certificate containing a particular manufacturer name unless it has independently verified the identity of the manufacturer. This prevents a counterfeiter spoofing a manufacturer name. The reader uses the public key to authenticate the authentication result message. The authentication result message includes the name of the product class. This prevents a counterfeiter from spoofing a product class name. The reader plays back or displays the name of the manufacturer and the name of the product class to the user.

[0799] As an alternative to the reader obtaining the manufacturer's certificate from the CA, it can obtain the certificate from some other source (such as the product service), and merely authenticate the certificate using the corresponding CA's signature public key.

[0800] The product service ID and manufacturer ID are one and the same, then the reader doesn't need to authenticate the result message. However, it still needs to derive the manufacturer name from the manufacturer's certificate. Note that a single CA is backed by a hierarchy of trust, and a CA can itself be authenticated with respect to a parent CA in the hierarchy, and so on back to the root CA. The reader typically caches the authenticated certificates of recently-encountered manufacturers and their CAs.

[0801] As described earlier, each product item can have a record of ownership and a history of scan events, possibly relating to aggregates (such as cartons or pallets) containing the product item. These constitute the product item's pedigree. In general there is a one-to-many relationship between ownership records and scan event records, and changes in ownership are typically triggered by particular scan events.

[0802] The authentication result message sent by the product service to the reader, and subsequently played back or displayed to the user, can include pedigree information to help the user ascertain the status of the product item. This can indicate to the user the manufacturing and distribution path the item has followed, or simply indicate when and where the item was sold (as discussed further below).

[0803] If the product item has been recorded as stolen, either individually or as part of an aggregate, then the user can also be alerted when they request authentication of the item. The authentication message then indicates that the item is stolen.

[0804] FIG. 65 shows an example authentication message displayed on a mobile phone.

[0805] Most item ID carriers, including barcodes and RFID tags, are susceptible to exact duplication. Since the inclusion of a digital signature makes it impractical for a counterfeiter to produce a counterfeit item carrying a novel item ID, the counterfeiter is reduced to duplicating an item already seen. The item's pedigree can be used to detect such duplication, although such detection may devolve to the end user.

[0806] As an example, a counterfeiter may purchase an authentic pharmaceutical item and duplicate its packaging a thousand times, including its item ID and digital signature carrier, to produce a thousand counterfeit items filled with counterfeit and possibly ineffective or unsafe product. An unsuspecting purchaser, when authenticating the item as discussed above, would find it authentic. The counterfeiter, rather than purchasing the original product item, could alternatively harvest the item ID and signature of an item still in distribution or on the retail shelf.

[0807] To prevent this exploit, when a user attempts to purchase an object by reading its identifier, the Netpage server looks up a transaction history for the object and allows the transaction to proceed only if there have been no previous transactions for its item ID. If there have been any previous transactions, an indication of these transactions (in the form of “transaction history data”) can be sent to the user. The transaction history data sent to the user may indicate the time and possibly place the item was sold. The transaction history data may also indicate the identity of a reader used to record any previous transactions or a user who has recorded himself as the owner of the object. Hence, the user can conclude that either the object is second-hand or that the item's ID was harvested, in which case the object is probably a counterfeit.

[0808] If the user purchases a counterfeit item through an unconventional channel, then they may have no expectation that its pedigree will reflect their purchase, since they may have an expectation that the item is being re-sold or is being sold by someone who does not record sales. To protect such a user from a counterfeit, they can be given the power to register their purchase of the item, possibly anonymously. Since only one user can register the purchase, all but one purchaser of a duplicated item can detect the duplication.

[0809] To prevent ‘denial-of-service’ attacks on this mechanism, where counterfeiters deliberately try to undermine the system by registering product items on the retail shelf as purchased, purchase registration can be restricted to product items already recorded as sold.

[0810] Harvesting and denial-of-service can also be prevented if the digital signature which confers the power to register the purchase of an item is protected (or masked) by a tamper-proof mechanism. For example, in the case of a printed carrier such as a barcode 211 or Hyperlabel tag pattern 4, the carrier for the digital signature can be hidden under a scratch-off layer 220 or it may simply be printed on an inside surface of packaging containing the object. The scratch-off layer 220 or the packaging serves as a visible indicator of tampering. The product item 200 then typically carries two digital signatures: one used to authenticate scan events in the supply chain, and the other used by the end user to authenticate the item post-purchase, and register the item as purchased. Alternatively or additionally, the user can also use the public digital signature to authenticate the item, and use the tamper-proof digital signature to register the purchase.

[0811] A reader in the supply chain can use the digital signature associated with an item (or aggregate) to authenticate the k item before generating a scan event, or can transmit the digital signature as part of the scan event to allow the product service to authenticate the product item, as shown in FIG. 66. This prevents counterfeit scan events from being recorded as part of an item's pedigree, i.e. it prevents a counterfeit pedigree from being established for a counterfeit or diverted item. In the Figure the product service represents the distributed set of supply chain services, run by manufacturers, distributors and retailers, which record and serve information about product items. As described earlier, the scan event identifies the reader (scanner), and the time and location of the scan.

[0812] The reader and product service can also utilise encryption and/or digital signing in their communications to prevent counterfeit scan events from being accepted. For example, each reader can be registered with the product service and have its own private key for signing scan events, and the product service can authenticate each signed scan event using the reader's corresponding public key before accepting and recording the scan event.

[0813] It will, of course, be appreciated that the present invention has been described purely by way of example and that modifications of detail may be made within the scope of the invention, which is defined by the accompanying. claims.