Security system and method
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.
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.
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.
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.
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.
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.