Automatic data generation for self-test of cryptographic hash al

Details Automatic data generation for self-test of cryptographic hash al Automatic data generation for self-test of cryptographic hash al

1995-08-31

1997-04-22

Gregory, Bernarr E.

Cryptography

Equipment test or malfunction indication

380 28, 380 46, 380 49, 331 78, 364717, 324 731, H04K 100, H04L 928

Patent

active

056235453

ABSTRACT:
According to the present invention, the solution includes the hardware hash algorithm block to automatically generate data to hash from its initialization values and to run unassisted instead of needing a continuous supply of additional input data. This approach according to the present invention solves the above shortcomings of related solutions by eliminating the need to continuously feed input data to be hashed to obtain a high fault coverage. This reduces the sizes of the firmware and test vectors necessary to test the hardware. Also, since the hardware autonomously generates new data to hash, other hardware modules can be tested in parallel. This reduces the overall test time and cost. To remove the requirement of inputting multiple fixed length sub-blocks, additional sub-blocks are created from the initial sub-block using a hardware expansion function, and the hardware continues to run unattended for some predetermined number of sub-blocks. The hash hardware can use the expansion function, W[i]=W[i-3] xor W[i-8] xor W[i-14] xor W[i-16], to expand existing data into new data, where W[i-x] originates from the initial sub-block. By utilizing the non-linear xor function, W[i] will be random data if any of W[i-3], W[i-8], W[i-14], or W[i-16] are random. This expansion function is good for achieving high fault coverage because the new W values will likely be different from the other W values that have been hashed. This expansion function is convenient to use because it is utilized by the Secure Hash Algorithm as specified by the Secure Hash Standard FIPS PUB 180 and FIPS PUB 180-1 (includes a left rotate by one bit position).

REFERENCES:
patent: 4680539 (1987-07-01), Tsai

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