Developed by NIST, specified in the Secure Hash Standard, originally 1993
Revised as SHA-1 in 1995
160 bit hash
NIST specified SHA2 algorithms in 2002
Hash value lengths of 256, 384, and 512
Similar to SHA-1
SHA-1, SHA-256, SHA-384, SHA-512
Message digest size, Message size, Block size, Word size, Number of steps, Security
Message Processing
Message Digest Generation using SHA-512
SHA-512 Processing of a Single 1024-bit block
Hash based message authentication
– cryptographic hash functions generally execute faster
– library code is widely available
– SHA-1 was not designed for use as a MAC because it does not rely on a secret key
– issued as RFC2014
– Has been chosen as the mandatory-to-implement MAC for IP security
– Used in other Internet protocols such as Transport Layer Security(TLS)
HMAC Security
– security depends on the cryptographic strength of the underlying hash function
– It’s much harder to launch successful collision attacks on HMAC because of secret key
