Digital Signatures

• US 20100293384A1
• Filed: 05/12/2009
• Published: 11/18/2010
• Est. Priority Date: 05/12/2009
• Status: Active Grant

• Current Assignee: Empire Technology Development LLC (Allied Inventors Management, LLC), Regents of the University of California (University of California)
• Original Assignee: Aristaeus Hermes LLC
• Inventors: Potkonjak, Miodrag
• Granted Patent: US 8,850,281 B2
• Time in Patent Office: Days
• US Class Current: 713/176
• CPC Class Codes: H04L 2209/12 Details relating to cryptographic hardware or logic circuitry
• CPC Class Codes: H04L 2209/56 Financial cryptography, e.g. electronic payment or e-cash
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 9/3247 involving digital signatures
• CPC Class Codes: H04L 9/3278 using physically unclonable functions [PUF]

Abstract

Technologies are generally described for secure digital signatures that employ hardware public physically unclonable functions. Each unique digital signature generator can be implemented as hardware such that manufacturing variations provide measurable performance differences resulting in unique, unclonable devices or systems. For example, slight timing variations through a large number of logic gates may be used as a hardware public physically unclonable function of the digital signature unit. The hardware digital signature unit can be parameterized such that its physical characteristics may be publicly distributed to signature verifiers. The verifiers may then simulate randomly selected portions of the signature for verification.

Claims

1. A digital signature generation device comprising:

a hardware public physically unclonable function having unique operational characteristics capable of being parameterized;

an input register for loading signals into the hardware public physically unclonable function; and

two or more output registers respectively connected within the hardware public physically unclonable function for delivering digital signature values from two or more layers within the hardware public physically unclonable function.

2. The digital signature generation device of claim 1, further comprising a timing mechanism for determining timing for latching result values at each of the two or more output registers.

3. The digital signature generation device of claim 1, further comprising an interface to a host computer, wherein the interface is coupled to the input register and the two or more output registers.

4. The digital signature generation device of claim 1, wherein the hardware public physically unclonable function operates with a time less than a time used for simulating the hardware public physically unclonable function from the parameterized characteristics.

5. The digital signature generation device of claim 1, wherein the hardware public physically unclonable function comprises a plurality of logic gates.

6. The digital signature generation device of claim 1, wherein the hardware public physically unclonable function comprises nanowires.

7. The digital signature generation device of claim 1, wherein the hardware public physically unclonable function comprises photonic crystals.

8. A method for generating digital signatures using a hardware public physically unclonable function, the method comprising:

loading initial values associated with a message to be signed into an input register associated with the hardware public physically unclonable function;

coupling logic signals corresponding to the initial values from the input register into the hardware public physically unclonable function;

propagating the logic signals through the hardware public physically unclonable function so as to transform the logic signals; and

latching the transformed logic signals from the hardware public physically unclonable function into two or more output register.

9. The method of claim 8, further comprising initializing the input register to a known state prior to loading the initial values.

10. The method of claim 8, wherein the hardware public physically unclonable function generates a result with a time less than a time used for simulating the hardware public physically unclonable function to generate the result.

11. The method of claim 8, wherein the hardware public physically unclonable function comprises a plurality of logic gates.

12. The method of claim 8, wherein the hardware public physically unclonable function comprises nanowires.

13. The method of claim 8, wherein the initial values are generated by hashing the message to be signed.

14. The method of claim 8, further comprising receiving a digital signature request comprising a message to be signed and a timing specification for latching the transformed logic signals into the two or more output registers.

16. The computer storage medium of claim 8, wherein selecting portions of the digital signature comprises random selection.

17. The computer storage medium of claim 8, wherein the simulated digital signature is based upon initial values associated with the signed document and timing specifications for latching outputs from the hardware public physically unclonable function.

18. The computer storage medium of claim 8, wherein the expected result comprises a set of results generated within a tolerance window of time.

19. The computer storage medium of claim 8, wherein the selected portion of the received digital signature comprises a portion between two or more specified output registers associated with the hardware public physically unclonable function.

20. The computer storage medium of claim 8, wherein the hardware public physically unclonable function comprises a plurality of logic gates.

15. A computer storage medium having computer-executable instructions stored thereon which, when executed by a computer system, cause the computer system to:

receive information characterizing unique parameters associated with a hardware public physically unclonable function;

receive a signed document comprising a digital signature;

select portions of the digital signature to generate by simulation;

simulate the hardware public physically unclonable function based on the information characterizing unique parameters to generate an expected result for the selected portion of the digital signature;

classify the digital signature as valid in response to matching the expected result for the selected portion of the digital signature with the selected portion of the received digital signature; and

classify the digital signature as suspect in response to a failure to match the expected result for the selected portion of the digital signature with the selected portion of the received digital signature.