Personal date/time notary device

• US 5,422,953 A
• Filed: 05/05/1993
• Issued: 06/06/1995
• Est. Priority Date: 05/05/1993
• Status: Expired due to Term

• Current Assignee: Addison M. Fischer
• Original Assignee: Addison M. Fischer
• Inventors: Fischer, Addison M.
• Primary Examiner(s): Cain, David C.
• Application Number:
  US08/056,547
• Time in Patent Office: 762 Days
• Field of Search: 380/23, 380/25, 380/49, 380/30, 380/28
• US Class Current: 713/172
• CPC Class Codes: G06F 21/725 operating on a secure reference time value
• CPC Class Codes: G06Q 20/341 Active cards, i.e. cards including their own processing means, e.g. including an IC or chip
• CPC Class Codes: G06Q 20/346 Cards serving only as information carrier of service
• CPC Class Codes: G06Q 20/40975 using encryption therefor
• CPC Class Codes: G07F 7/08 by coded identity card or credit card or other personal identification means without personal verification means G07F7/02
• CPC Class Codes: G07F 7/1008 Active credit-cards provided with means to personalise their use, e.g. with PIN-introduction/comparison system
• CPC Class Codes: G07F 7/12 Card verification
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3297 involving time stamps, e.g. generation of time stamps

Abstract

A personal data/time notary device is embodied in a token device such as a "smart card". The portable notary device includes an input/output (I/O) port, which is coupled to a single integrated circuit chip. The I/O port may be coupled to a conventional smart card reading device which in turn is coupled to a PC, lap-top computer or the like. A tamper resistant secret private key storage is embodied on the chip. The private key storage is coupled to the processor which, in turn, is coupled to a permanent memory that stores the program executed by the processor. At least one clock is embodied on the card. A second clock 14 and a random value generator 10 are also preferably coupled to the processor. The device combines digital time notarization into a digital signature operation to ensure that a time stamp is always automatically present. The user does not need to be involved in any additional decision making as to whether time stamping is necessary.

Claims

1. A portable token device fabricated on a portable medium and sized so as to be readily carried or worn by a user comprising:

a token device medium substantially credit card-sized so as to be readily carried or worn by a user and having fabricated therein;

a secure storage device for storing a user'"'"'s private key, wherein said at least one private key is used to perform digital signatures associated with said user and wherein said user'"'"'s private key has an associated public key identified with said user;

a clock for providing an indication of date and time;

a communication port for receiving a value to be digitally signed and for emitting an output;

a processor device coupled to said communication port and said clock for receiving said value to be digitally signed and said indication of date and time and for performing at least one digital signature with said at least one private key for output to said communication port.

2. A device according to claim 1, further comprising a random number generator coupled to said processor device.

3. A device according to claim 1, further including an additional clock coupled to said processor device.

4. A device according to claim 1, wherein said processor device includes means for validating a user'"'"'s personal identification password (PIN) as a prerequisite to providing the digital signature.

5. A device according to claim 1, wherein said processor device is prevented from performing digital signatures in response to attempted tampering.

6. A device according to claim 1, wherein said secure storage device stores a plurality of private keys, said processor devices performs at least one digital signature operation using said plurality of private keys.

7. A method for operating a user'"'"'s portable token device comprising the steps of:

a) receiving a digital value to be digitally signed by a substantially credit card-sized medium carried by a user;

b) determining the current time from a trusted clock source embodied within said credit card sized medium;

c) creating a digital data structure including the current time, and a value derived from information to be signed;

d) accessing a user'"'"'s stored private key which has an associated public key identified with said user; and

e) digitally signing digital data said structure.

8. A method according to claim 7, wherein said stored private key has an associated public key certified as having its private key operating from within a secure time notary device.

9. A method according to claim 7, wherein at least one certificate associated with said at least one stored private key is stored in the device.

10. A method according to claim 7, wherein one of the certificates associated with said at least one stored private key are stored outside of the device.

11. A method according to claim 7, wherein said clock is permanently initialized at the time of manufacture.

12. A method according to claim 7, further including the step of accessing a plurality of private keys, wherein said at least one of said private keys is created at time of manufacture.

13. A portable user token device based system comprising:

secure storage means for storing a user'"'"'s private key, wherein said user'"'"'s private key is used to perform digital signatures associated with said user and wherein said user'"'"'s private key has an associated public key identified with said user;

communication means for receiving input digital signal and emitting digital output;

processor means for receiving said input digital signals and for performing digital signatures with the said at least one private key; and

means for interfacing with a trusted date-time notary device and for coupling via said communication means date and time related signals generated by said notary device to said processor means.

14. A system according to claim 13 wherein said secure storage means stores information used to identify a trusted date time notary device.

15. A system according to claim 13 wherein said means for interfacing is coupled in use to at least one interface reader device for supplying input and output to the token device coupled to at least one trusted time notary device.

16. A method for calibrating an on-chip clock device to compensate for individual deviation, including the steps of taking a first clock reading from a master clock;

storing the first clock reading;

taking a second clock reading from the master clock;

storing the second clock reading;

counting the number of oscillations between the master clock readings;

determining the actual oscillation frequency using the difference between the second and first master clock readings to compute oscillations per unit time;

storing the calculated oscillation frequency; and

adjusting the output of the on-chip clock device in accordance with said calculated oscillation frequency.

17. A method according to claim 16, wherein a calibration value computed for a clock of a time notary device is stored in memory in said device.

18. A method according to 16, wherein the on-chip clock indicates current time, which after calibration is computed with the steps of:

counting the number of oscillations since the first clock reading;

dividing said number of oscillations by the calibration value to obtain an adjustment value;

adding said adjustment value to the said first clock reading.

19. A portable, token device fabricated on a portable medium so as to be readily carried or worn by a user comprising:

a token device medium being substantially diskette-sized so as to be conveniently carried by a user and having fabricated therein;

a secure storage device for storing a user'"'"'s private key, wherein said at least one private key is used to perform digital signatures associated with said user and wherein said user'"'"'s private key has an associated public key identified with said user;

a clock for providing an indication of date and time;

a communication port for receiving a value to be digitally signed and for emitting an output;

a processor device coupled to said communication port and said clock for receiving said value to be digitally signed and said indication of date and time and for performing at least one digital signature with said at least one private key for output to said communication port.

20. A device according to claim 19, wherein said processor device includes means for validating a user'"'"'s personal identification password (PIN) as a prerequisite to providing the digital signature.

21. A portable, token device fabricated on a portable medium and sized so as to be readily carried or worn by a user comprising:

an item designed to be worn by a user having fabricated therein;

a secure storage device for storing a user'"'"'s private key, wherein said at least one private key is used to perform digital signatures associated with said user and wherein said user'"'"'s private key has an associated public key identified with said user;

a clock for providing an indication of date and time;

a communication port for receiving a value to be digitally signed and for emitting an output;

a processor device coupled to said communication port and said clock for receiving said value to be digitally signed and said indication of date and time and for performing at least one digital signature with said at least one private key for output to said communication port.

22. A device according to claim 21, wherein said processor device includes means for validating a user'"'"'s personal identification password (PIN) as a prerequisite to providing the digital signature.