Security system and method

• US 7,818,572 B2
• Filed: 07/28/2004
• Issued: 10/19/2010
• Est. Priority Date: 12/09/2003
• Status: Active Grant

• Current Assignee: Dominic Kotab
• Original Assignee: Dominic Kotab
• Inventors: Paley, Daniel Noah, Stewart, Roger Green
• Primary Examiner(s): Barron, Jr.; Gilberto
• Assistant Examiner(s): Okeke; Izunna
• Application Number:
  US10/902,683
• Publication Number:
  US 20050123133A1
• Time in Patent Office: 2,274 Days
• Field of Search: 713/168, 713/169, 713/171, 713/181, 380/46, 380/262, 380/265, 380/268
• US Class Current: 713/169
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 63/0428 wherein the data content is protected, e.g. by encrypting or encapsulating the payload
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 9/3271 using challenge-response

Abstract

A first embodiment provides a process and system for simple, secure exchange of random numbers between two devices by combining a random number and a secret code (e.g., password) to generate a first challenge code, extracting the random number using the password at the second device, combining the first random number with a second random number, and returning the combination to the first device, which extracts the second random number from the second challenge code using its first random number. A CRC can be added to authenticate the sender. Another embodiment provides a system and method for generating a seedless pseudo-random number. The Yet another embodiment provides a system and method for generating data encryption coding with variable clocking.

Claims

1. A method for exchanging random numbers, comprising:

generating a first random number;

generating a first challenge code using the first random number and a secret code, wherein generating the first challenge code uses an exclusive OR function;

transmitting the first challenge code from a first device to a second device, the first and second devices knowing the secret code;

extracting the first random number from the first challenge code at the second device using the secret code;

generating a second random number at the second device;

generating a second challenge code using the extracted first random number and the second random number, wherein generating the second challenge code uses an exclusive OR function;

transmitting the second challenge code from the second device to the first device; and

extracting the second random number from the second challenge code.

2. A method as recited in claim 1, wherein at least one of the random numbers is seedless.

3. A method as recited in claim 1, wherein the first random number is of higher quality than the second random number.

4. A method as recited in claim 3, wherein first random number of higher quality protects the lower quality random number in the second challenge.

5. A method as recited in claim 3, wherein the first device is a more complex device than the second device, wherein the first device generates the first random number of higher quality.

6. A method as recited in claim 1, wherein the first device is a reader, the second device is a radio frequency (RF) tag.

7. A method as recited in claim 1, further comprising transmitting a cyclic redundancy check from the first device to the second device.

8. A method as recited in claim 7, wherein the cyclic redundancy check is used to verify the first random number.

9. A method as recited in claim 7, wherein the cyclic redundancy check in the first challenge code is exclusively ORed against the secret code.

10. A method as recited in claim 1, further comprising transmitting a cyclic redundancy check from the second device to the first device.

11. A method as recited in claim 10, wherein the cyclic redundancy check is used to verify at least the second random number.

12. A method as recited in claim 10, wherein the cyclic redundancy check in the second challenge code is exclusively ORed against the first random number.

13. A system for exchanging random numbers, comprising:

a circuit for generating a first random number;

a circuit for generating a first challenge code using the first random number and a secret code, wherein an exclusive OR function is used for generating the first challenge code;

a circuit for transmitting the first challenge code from a first device to a second device using a wireless link, the first and second devices knowing the secret code;

a circuit for extracting the first random number from the first challenge code at the second device using the secret code;

a circuit for generating a second random number at the second device;

a circuit for generating a second challenge code using the extracted first random number and the second random number, wherein an exclusive OR function is used for generating the second challenge code;

a circuit for transmitting the second challenge code from the second device to the first device; and

a circuit for extracting the second random number from the second challenge code.

23. A system as recited in claim 13, wherein the first random number is of higher quality than the second random number.

24. A system as recited in claim 23, wherein first random number of higher quality protects the lower quality random number in the second challenge.

25. A system as recited in claim 23, wherein the first device is a more complex device than the second device, wherein the first device generates the first random number of higher quality.

26. A system as recited in claim 13, wherein the first device is a reader, the second device is a radio frequency (RF) tag.

27. A system as recited in claim 13, further comprising logic for transmitting a cyclic redundancy check from the first device to the second device.

28. A system as recited in claim 27, wherein the cyclic redundancy check is used to verify the first random number.

29. A system as recited in claim 27, wherein the cyclic redundancy check in the first challenge code is exclusively ORed against the secret code.

30. A system as recited in claim 13, further comprising logic for transmitting a cyclic redundancy check from the second device to the first device.

31. A system as recited in claim 30, wherein the cyclic redundancy check is used to verify at least the second random number.

32. A system as recited in claim 30, wherein the cyclic redundancy check in the second challenge code is exclusively ORed against the first random number.

14. A method for exchanging random numbers, comprising:

sharing a secret code between first and second devices in a secure environment;

generating a first random number;

generating a first challenge code by exclusive ORing (XORing) the first random number and the secret code;

transmitting the first challenge code from a first device to a second device in a non-secure environment, the first and second devices knowing the secret code;

extracting the first random number from the first challenge code at the second device using the secret code and inverse XORing;

generating a second random number at the second device, wherein the first random number is of higher quality than the second random number;

generating a second challenge code by XORing the extracted first random number and the second random number;

transmitting the second challenge code from the second device to the local device in a non-secure environment; and

extracting the second random number from the second challenge code at the first device by inverse XORing.

33. A method as recited in claim 14, wherein the first random number is of higher quality than the second random number.

34. A method as recited in claim 33, wherein first random number of higher quality protects the lower quality random number in the second challenge.

35. A method as recited in claim 33, wherein the first device is a more complex device than the second device, wherein the first device generates the first random number of higher quality.

36. A method as recited in claim 14, wherein the first device is a reader, the second device is a radio frequency (RF) tag.

37. A method as recited in claim 14, further comprising logic for transmitting a cyclic redundancy check from the first device to the second device.

38. A method as recited in claim 37, wherein the cyclic redundancy check is used to verify the first random number.

39. A method as recited in claim 37, wherein the cyclic redundancy check in the first challenge code is exclusively ORed against the secret code.

40. A method as recited in claim 14, further comprising logic for transmitting a cyclic redundancy check from the second device to the first device.

41. A method as recited in claim 40, wherein the cyclic redundancy check is used to verify at least the second random number.

42. A method as recited in claim 40, wherein the cyclic redundancy check in the second challenge code is exclusively ORed against the first random number.

15. A method for authenticating a data source using a cyclical redundancy check on encrypted data, comprising:

receiving a challenge containing an encrypted random number from a remote device;

receiving a cyclical redundancy check purporting to correspond to the encrypted random number;

decrypting the random number;

checking the random number against the cyclical redundancy check;

establishing a communications link with the remote device if the random number matches the cyclical redundancy check;

not establishing a communications link with the remote device if the random number does not match the cyclical redundancy check.

16. A method as recited in claim 15, wherein the cyclic redundancy check is part of the challenge.

17. A method as recited in claim 15, wherein the cyclic redundancy check is exclusively ORed against a secret code.

18. A method as recited in claim 15, wherein the cyclic redundancy check is combined with the random number and the combination is exclusively ORed against a secret code.

19. A method as recited in claim 15, wherein the cyclic redundancy check is exclusively ORed against another random number.

20. A method as recited in claim 15, wherein the cyclic redundancy check is combined with the random number and the combination is exclusively ORed against another random number.

21. A method as recited in claim 15, wherein the method is performed by an RFID tag.

22. A method as recited in claim 15, wherein the method is performed by an RFID reader.