Cryptography General Question:

The Secure Hash Algorithm (SHA), the algorithm specified in the Secure Hash Standard (SHS), was developed by NIST and published as a federal information processing standard (FIPS PUB 180). SHA-1 was a revision to SHA that was published in 1994. The revision corrected an unpublished flaw in SHA. Its design is very similar to the MD4 family of hash functions developed by Rivest.