SHA-2

In cryptography, SHA-2 is a set of cryptographic hash functions (SHA-224, SHA-256, SHA-384, SHA-512) designed by the National Security Agency (NSA) and published in 2001 by the NIST as a U.S. Federal Information Processing Standard. SHA-2 includes a significant number of changes from its predecessor, SHA-1. SHA-2 consists of set of four hash functions with different digest sizes, with 224, 256, 384 or 512 bits respectively.

In 2005, security flaws were identified in SHA-1, namely that a mathematical weakness might exist, indicating that a stronger hash function would be desirable. Although SHA-2 bears some similarity to the SHA-1 algorithm, these attacks have not been extended to SHA-2.

A new hash standard, SHA-3, is currently under development — an ongoingNIST hash function competition is scheduled to end with the selection of a winning function in 2012. The SHA-3 algorithm will not be derived from SHA-2.