51.4 Functional Description

The Secure Hash Algorithm (SHA) module requires a padded message according to the FIPS 180 specification. This message can be provided with the padding to the SHA module, or the padding can be automatically computed by the SHA module if the size of the message is provided. The first block of the message must be indicated to the module by a specific command. The SHA module produces an N-bit message digest each time a block is written and processing period ends, where N is 160 for SHA1, 224 for SHA224, 256 for SHA256, 384 for SHA384, 512 for SHA512. The SHA module is also capable of computing a Hash-based Message Authentication Code (HMAC) algorithm.