Method and apparatus for controlling release of time sensitive information

[0002] This invention relates generally to conveyance of information and more particularly to controlling the release of time sensitive information.

[0003] Conveyance of data between parties is known. Such conveyance may be done over wireline transmission paths such as telephone lines, the Internet, etc., and done between data devices such as facsimile machines, computers, etc. Additionally, conveyance of information may be done over wireless transmission paths between wireless communication devices such as portable radios, portable computers that include an RF transceiver, personal digital assistance (PDA), etc. The information conveyed between parties, whether over a wireless communication path or wire line communication path, may be transmitted in a secure manner utilizing encryption and decryption algorithms or may be transmitted in clear text.

[0004] For secured conveyances of data, the sending party encrypts the data using an encryption algorithm and a particular key. The key may be a public encryption key of the intended recipient or a unique key for this particular communication. Having encrypted the information, the sending party transmits the encrypted data along with an indication of the particular key to the recipient party. Upon receiving the encrypted data, the recipient obtains, or recaptures, the key and subsequently decrypts the data.

[0005] If such data, whether in clear text or in a secured manner, is transmitted to multiple parties, each of the receiving parties may receive the data at different times. For example, if a company is releasing internal information as to a reorganization, the employees at the corporate headquarters, where the message was originated, would most likely receive the message considerably sooner than employees stationed in other parts of the country and/or world. Such information could be considered to be time-sensitive if the releasing party wants the recipients to have access to the data at the same future time.

[0006] Currently, if the releasing party is releasing time-sensitive information, the releasing party has to rely on the recipients to access the information only when requested to do so. In other words, the releasing parties has to rely on the integrity of the recipients not to access the information before requested. While most people would honor the request, some would not. Therefore, a need exists for a method and apparatus that provides the releasing party with automatic control over the releasing of time-sensitive information.

[0007] FIG. 1 illustrates a schematic block diagram of a local area network or wide area network which is in accordance with the present invention;

[0008] FIG. 2 illustrates a graphical representation of a calculation for a release of time sensitive information in accordance with the present invention;

[0009] FIG. 3 illustrates a logic diagram for controlling release of time-sensitive information;

[0010] FIG. 4 illustrates a logic diagram for encrypting time-sensitive information and subsequently releasing information such that the time-sensitive information may be decrypted in accordance with the present invention;

[0011] FIG. 5 illustrates a logic diagram that may be used by an end-user to prepare time sensitive information and also to receive time-sensitive information in accordance with the present invention; and

[0012] FIG. 6 illustrates a logic diagram for preparing time-sensitive information in accordance with the present invention.

[0013] Generally, the present invention provides a method and apparatus for controlling release of time-sensitive information. This may be accomplished by a server establishing access information for a specific future time which only becomes available once the specific future time has passed. When the specific future time has passed, the server releases the access information such that an end-user or end-users may utilize the access information to obtain time-sensitive information. The access information may be a random number which can be used to calculate a decryption key and an encryption key. The encryption key can be released by the server at any time such that an end-user may encrypt time sensitive information for release at the specific future time, but the random number is not released until the specific future time has passed. When the random number is released, end-users may generate the decryption key and subsequently decrypt the time-sensitive information. With such a method and apparatus, time-sensitive information can be released at any time and accessed only at a specific future time based on the release of access information relating to the specific future time.

[0014] The present invention can be more fully described with reference 1 through 6. FIG. 1 illustrates a wide area network (“WAN”) or local area network (“LAN”) 10 that includes a server 12 and a plurality of end-users 14-22. Each of the end-users 14-22 include memory 26-34. Such memory may be random access memory, read-only memory, hard drive, disk drive and associated disks, or any other means for storing digital information. The server 12 includes a processing unit 23 and memory 24. The processing unit may be a microprocessor, micro-controller, microcomputer, digital signal processor or any other device that manipulates digital information based on programming instructions. The memory may be read-only memory, RAM, magnetic tape, hard drive, CD ROM, disk drive and associated disks, or any other means for storing digital information. Typically, the memory 24 will store programming instructions such that, when read by the processing unit 23, causes the processing unit 23 to perform the functions illustrated in one of, or all of, the logic diagrams of FIGS. 3 through 6. Note that the server 12 and the end-users 12-22 may be personal computers, work stations, or any other device that manipulated digital information based on programming instructions. Further note that the server 12 may be incorporated in one or more of the end-users 14-22, but, for the convenience of this discussion, will be discussed as a separate entity.

[0015] In an example of operation, assume that an end-user 14 has time sensitive information that it desires to be released at some future point-in-time, where the time-sensitive information may be a press release, a corporate announcement, release of a combination for a bank safe, or any type of information that a user desires to release to a recipient or plurality of recipients at a specific future time. Having decided to release time sensitive information, the end-user 14 sends a request for an encryption key to the server 12 via the WAN or LAN, which may be the Internet, asynchronous transfer mode infrastructure, or any other means for conveying digital data between sites.

[0016] Prior to granting the end-user's 14 request, the server 12 generates, at time T₀, a specific random number for a specific future time. For example, the specific future time may be 20 years from today's date. For this specific future time, a random number is generated. From this random number, iteratively using a one-way function, such as SHA-1, secret numbers may be generated for any time prior to the specific future time and for any time interval. For example, secret numbers may be iteratively generated at hour increments dating back from the specific future time, which, as stated, may be 20 years from today's date. Thus, if a straight forward one-way function were utilized a 175,000 calculations of the one-way function would need to be performed to obtain the secret number of the first hour of today, which is the first hour of the first day of the first month of the first year of the time controlled releasing period. The discussion involving FIG. 2 presents a technique for calculating secret numbers for any time within the time controlled releasing period using a maximum of 84 calculations for a 20 year period.

[0017] Continuing with the example, as mentioned, at T₁, end-user 14 has time-sensitive information 36 which it desires to release at some future point-in-time and has made a request to the server 12 for an encryption key. The request identifies the future point-in-time when the time-sensitive information is to be released and may or may not contain the time sensitive information. If it includes the time sensitive information, the server 12 will encrypt the information and release the encrypted information. If the request does not include the information, the end-user will encrypt the information and release the encrypted information. Upon receiving the request, the server 12 calculates a secret number for the specified future point-in-time based on the specific future time, the specified future point-in-time specified, the random number, and the one-way function. Once the secret number has been calculated, the server generates a key pair. If the system is employing a Diffie Hellman or elliptic curved cryptic system, a private key can simply be the secret number with a corresponding public key being dependent thereon. If, however, the system is employing an RSA technique, the secret number is used to generate a unique private decryption key and a corresponding public encryption key.

[0018] Having generated the public encryption key, the server 12, at time T₂, sends the encryption key to the end-user 14. Upon receiving the encryption key, the end-user 14 encrypts the time-sensitive information 36 and transmits it to the network at time T₃. At this point, each of the recipient end-users will have a copy of the encrypted time-sensitive information 36. However, none of the recipients may decrypt the information until the specified future point-in-time has passed.

[0019] When the specified future point-in-time has passed, the server 12 releases the corresponding secret number (“CSN”) at time T₄. At this time, each of the recipient end-users 16-22 receive the corresponding secret number and subsequently generates the private decryption key therefrom. As one skilled in the art will readily appreciate, the secret numbers corresponding to any future time must be keep confidential until the corresponding time has passed.

[0020] Once the decryption key has been obtained, at T₅, from the corresponding secret number, the recipient end-users 16-22 decrypt the time-sensitive information to obtain the clear text representation thereof. Thus, the present invention achieves time-released cryptography with the desirable properties that time-enforcement is done using a server which can be controlled and the server need not deal directly with data to be encrypted.

[0021] FIG. 2 illustrates a graphical representation of a calculation of a plurality of random numbers that correspond to a specific future release time or a specific future point-in-time. In this example, the specific future point-in-time is 11:00 PM, Dec. 31, 2000. For this specific future point-in-time, one random number is generated by the server and is the only independent number for the entire time release process. The random number may then be used to calculate any secret number relating to a preceding point-in-time using the one-way functions for years f_y(S), for months f_m(S), for days f_d(S), and for hours f_h(S).

[0022] In general, given a secret number (S) corresponding to the last hour of the last day of the last month of the last year to be handled by the server for the time release process, i.e., final point-in-time or the specific future point-in-time, the last hour of the previous year is obtained by utilizing the one-way function for years f_y(S). By performing f_y(f_y(S)), the secret number for the last hour of the next previous year is obtained. The secret number for the last hour of other previous years is obtained in the same manner. Within any given year upto and including the last year of the time release process, a secret number for the last hour of the last day of the next to last month may be obtained by utilizing the one-way function for months f_m(S1), where S1 is the secret number corresponding to the last hour of the last day of the last month of the given year. By performing f_m(f_m(S1)), the secret number for the last hour of the last day of the second to last month is obtained. The secret number for the last hour of the last day of other previous months within the given year is obtained in the same manner.

[0023] Within any given month of any given year, a secret number may be obtained for the last hour of any day by performing the one-way function for days f_d(S2) as many times as required to obtain the desired day, where S2 is the secret number corresponding to the last hour of the last day of the given month of the given year. For example, by performing f_d(f_d(S2)), the secret number for the last hour of the second to last day of the given month is obtained. The secret number for the last hour of other previous days within the given month is obtained in the same manner. A secret number for any hour in a given day of a given month of a given year can be obtained by utilizing the one-way function for hours f_h(S3) as many times as required to obtain the desired hour, where S3 is the secret number corresponding to the last hour of the given day of the given month of the given year. For example, by performing f_h(f_h(S3)), the secret number for the second to last hour is obtained. The secret number for other previous hours within the given day of the given month of the given year is obtained in the same manner.

[0024] Continuing with the general discussion, when a specific release time, or point-in-time, arrives, the server must release the secret number corresponding to the current hour such that the corresponding decryption key may be calculated by an end-user. The end-user may further use the secret number for the current hour, to calculate a secret number, and the corresponding decryption key, for any previous hour in the current day using the one-way function for hours f_h(S_ch), where S_chis the secret number for the current hour.

[0025] If the end-user desires to calculate a secret number for any hour during the previous day in the current month, the server must also release the secret number corresponding to the last hour of the previous day S_pd. The end-user would then use the one-way function f_h(S_pd) as many times as required to obtain the desired secret number. In, addition, from this secret number S_pd, the secret number of the last hour of any preceding day of the current month may be determined using the one-way function for days f_d(S_pd) as many times as required. From a secret number S_dcorresponding to a given day, a secret number may be calculated using the one-way function for hours f_h(S_d) as many times as required for any hour within the given day.

[0026] To calculate secret numbers for hours in preceding months of the current month within the current year, the server needs to release the secret number S_pmcorresponding to the last hour of the last day of the previous month to the current month. To calculate the secret number for the last hour of the last day of a preceding month within the current year, the one-way function for months f_m(S_pm) is used as many times as required. Using the secret number for a previous month of the current year, the secret number for the last hour of any day may be obtained using the one-way function for days. From these secret numbers for days, secret numbers for any hour in a given day can be calculated using the one-way function for days. To calculate the secret number for previous hours of the last day of the previous month, the one-way function for hours f_h(S_pm) is used as many times as required. To calculate the secret number for the last hour of any day in the previous month, the one-way function for days f_d(S_pm) is used as many times as required. From a secret number S_dcorresponding to a given day within the previous month, a secret number may be calculated using the one-way function for hours f_h(S_d) for any hour within the given day.

[0027] To obtain a secret number for any hour in a previous year, the server must release the secret number for the last hour of the last day of the last month for the previous year. From this secret number, any secret number can be determined for any hour using the one-way functions for hours, days, and months. As one skilled in the art will readily appreciate, given a secret number that corresponds to a given time (specified in hours, day, months, and/or years), a secret number may be calculated for any given previous time.

[0028] The example of FIG. 2 has the specified future point-in-time for the release of time-sensitive information being Jul. 4, 1998 at 6:00 a.m. To obtain the unique secret number for this time, the server 12 utilizes the random number for 11 PM, Dec. 31, 2000 and the one-way functions for years, months, days, and hours functions. To begin, the server 12 calculates a secret number (S1) for 11 PM, Dec. 31, 1998 by executing f_y(f_y(S)), where the nested f_y(S) provides the secret number for 11 PM, Dec. 31, 1999, and the outer f_y(S) provides the secret number (S1). Using the secret number S1, the server 12 calculates the secret number (S2) for the last hour of July, 1998 by performing the f_m(S1) function five times. From S2, the server then calculates the secret number S3 for the last hour of Jul. 4^th, 1998 by performing the f_d(S) function twenty-seven times (31−4). From S3, the server calculates the secret number (S4) for 6 AM, Jul. 4^th, 1998 by performing the f_h(S3) sixteen times (23−6 ). 84 can then be used to generate an encryption key that is used to decrypt time sensitive information which was scheduled for release at 6 AM, Jul. 4^th, 1998. Note that S1, S2, and S3 are secret number components of the secret number for 6 AM, Jul. 4^th, 1998.

[0029] Given the secret number (S4) for 6 AM, July 4^th, 1998 and secret numbers for the last hour of the previous day f_d(S3) (or f_m(S2) if S4 corresponds to the first day of the month), the secret number for the last hour of the previous month f_m(S2) (or f_y(S1) if S4 corresponds to the first month of the year), and the secret number for last hour of the previous year f_y(S1), the end-user can calculate any previous secret number and the associated decryption key.

[0030] As mentioned with reference to FIG. 1, if a 20-year span has been established for the time release period, the server would need to perform 175,000 calculations of a one-way function to obtain the secret number for the first hour of the first day of the first month of the first year of the release period. By using the technique described above to determine a secret number relating to a specific point-in-time, the maximum number of calculations to obtain any secret number for the 20 year period is down from 175,000 to 84.

[0031] FIG. 3 illustrates a logic diagram for accessing time-sensitive information. The process begins at step 50 where a server establishes access information for a specific future time. The access information may be a random number which would be used for encryption and decryption purposes, a combination for a bank safe, or any other access controlling information which can be time-released. Note that the access information is for a specific future time.

[0032] Having established the access information, the process proceeds to step 52 where a determination is made as to whether the specific future time has passed. If not, the process waits until the specific future time passes. Once the specific future time passes, the process proceeds to step 54 where the server releases the access information. Upon release of the access information, the process proceeds to step 56 where an end-user may utilize the access information to obtain time-sensitive information. Note that any time after the specific future time passes, the end-user may utilize the access information to obtain the time-sensitive information. For example, if the specific future time where Jul. 4, 1998 at 6:00 a.m., the end-user any time thereafter could utilize the access information to obtain the time-sensitive information.

[0033] FIG. 4 illustrates a logic diagram for encrypting time-sensitive information and subsequently decrypting the time-sensitive information once a specific point-in-time has passed. The process begins at step 60 where a server establishes a random number for a specific future time. Such a process was discussed previously with reference to FIGS. 1 and 2. The process then proceeds to step 62 where a calculation is made to determine a corresponding secret number for a point-in-time. Such a calculation is based on the random number, a one-way function, the point-in-time, and the specific future time. Having generated the corresponding secret number, the process proceeds to step 64. At step 64, an encryption key is generated from the corresponding secret number. As previously mentioned for RSA, the corresponding secret number would be used to generate a public encryption key while for Diffie Hellman encryption, the corresponding secret number would be the encryption key.

[0034] The process then proceeds to step 66 where a determination is made as to whether a request for the encryption key has been received. If so, the process proceeds to step 68 where the server releases the encryption key. Once the encryption key is released, or no requests have been received for release of the encryption key, the process proceeds to step 70. At step 70, a determination is made as to whether the point-in-time has passed. If not, the process reverts back to step 66, where the system waits for either a request for the encryption key, or the point-in-time to pass. Once the point-in-time has passed, the process proceeds to step 72 where the server releases the corresponding secret number. As previously discussed, once the corresponding secret number has been released, the recipient end-users may calculate a private decryption key from the corresponding secret number. As one skilled in the art will readily appreciate, by utilizing the one-way function such as SHA-1, end-users cannot determine future secret numbers based on a current secret number. Thus, the one-way function ensures that only corresponding secret numbers of points-in-time that have passed can be used to generate decryption keys. By controlling the generation of decryption keys, only time-sensitive information for which the corresponding specific point-in-time has passed will be accessible to recipients.

[0035] FIG. 5 illustrates a logic diagram for an end-user to generate time-sensitive information and to obtain time-sensitive information. The process begins at step 80 where, from time to time, the end-user requests an encryption key that is based on a secret number corresponding to a specific future time. The requests would indicate the specific future time such that the server could calculate the corresponding secret number utilizing a one-way function. From the corresponding secret number, the server could generate the encryption key where the encryption key may be a public encryption key if RSA is used.

[0036] The process then proceeds to step 82 where the end-user encrypts time-sensitive information based on the encryption key. As previously mentioned, the time-sensitive information may be a corporate announcement, a press release, stock information, banking information, combinations for safety deposit boxes, safes, etc., or any other information that a transmitting party would want the designated recipients to receive at a given time. The process then proceeds to step 84 where the encrypted time-sensitive information is provided to a network such that the recipients may receive the encrypted time-sensitive information.

[0037] The process continues at step 86 where, from time to time, an end-user requests a secret number that corresponds to a second future specific time. The second specific future time relates to the time release for encrypted time-sensitive information. The process then proceeds to step 88 where the secret number is received when the second specific future time has passed. The process then proceeds to step 90 where a decryption key is generated from the secret number such that the encrypted time-sensitive information may be decrypted.

[0038] FIG. 6 illustrates a logic diagram for utilizing a plurality of random numbers to represent a specific future time and intervening times. The process begins at step 100 where a random number is established for a specific future time, i.e., the end of the time controlled releasing period. The process then proceeds to step 102 where a plurality of secret numbers are calculated based on the random number, a point-in-time, the specific future time, and at least one one-way function. For example, referring to the example of FIG. 2 where the point-in-time is Jul. 4, 1988 at 6:00 a.m., the plurality of secret numbers would be S1 for 11 PM, Dec. 31^st, 1998, S2 for 11 PM, Jul. 31^st, 1998, S3 for 11 PM, Jul. 4^th, 1998, and S4 for 6 AM, Jul. 4^th, 1998.

[0039] The process then proceeds to step 104 where an encryption key is generated based on the second plurality of random numbers. In particular, the encryption key for the 6 AM, Jul. 4^th, 1998 release time, would be based on the secret number S4, which is derived from the plurality of secret numbers S1, S2, and S3. Having generated the encryption key, the process proceeds to step 106 where the encryption key is released such that time-sensitive information may be encrypted using the encrypted key.

[0040] The preceding discussion has presented a method and apparatus for controlling release of time-sensitive information. The control is obtained by having a server establish a random number for a future given time and calculating, using a one-way function, corresponding secret numbers for points-in-time that occur prior to the future specific time. By utilizing a one-way function to calculate the secret numbers, only secret numbers that correspond to times that have passed can be calculated. As such, the release of time-sensitive information is done in a controlled manner with assurances that the recipients will not have access to the data prior to the specific release time.