![]() In August 2002, FIPS PUB 180-2 became the new Secure Hash Standard, replacing FIPS PUB 180-1, which was released in April 1995. The algorithms were first published in 2001 in the draft FIPS PUB 180-2, at which time public review and comments were accepted. The algorithms are collectively known as SHA-2, named after their digest lengths (in bits): SHA-256, SHA-384, and SHA-512. With the publication of FIPS PUB 180-2, NIST added three additional hash functions in the SHA family. The blue components perform the following operations:Ĭh ( E, F, G ) = ( E ∧ F ) ⊕ ( ¬ E ∧ G ) is addition modulo 2 32 for SHA-256, or 2 64 for SHA-512. Hash standard One iteration in a SHA-2 family compression function. Īs of 2011, the best public attacks break preimage resistance for 52 out of 64 rounds of SHA-256 or 57 out of 80 rounds of SHA-512, and collision resistance for 46 out of 64 rounds of SHA-256. The United States has released the patent under a royalty-free license. The SHA-2 family of algorithms are patented in the U.S. SHA-2 was first published by the National Institute of Standards and Technology (NIST) as a U.S. SHA-512/224 and SHA-512/256 are also truncated versions of SHA-512, but the initial values are generated using the method described in Federal Information Processing Standards (FIPS) PUB 180-4. SHA-224 and SHA-384 are truncated versions of SHA-256 and SHA-512 respectively, computed with different initial values. They use different shift amounts and additive constants, but their structures are otherwise virtually identical, differing only in the number of rounds. SHA-256 and SHA-512 are novel hash functions computed with eight 32-bit and 64-bit words, respectively. SHA-2 includes significant changes from its predecessor, SHA-1. They are built using the Merkle–Damgård construction, from a one-way compression function itself built using the Davies–Meyer structure from a specialized block cipher. SHA-2 ( Secure Hash Algorithm 2) is a set of cryptographic hash functions designed by the United States National Security Agency (NSA) and first published in 2001. ![]() ![]() By guessing the hidden part of the state, length extension attacks on SHA-224 and SHA-384 succeed with probability 2 −(256−224) = 2 −32 > 2 −224 and 2 −(512−384) = 2 −128 > 2 −384 respectively. SHA-256 and SHA-512 are prone to length extension attacks. Pseudo-collision attack against up to 46 rounds of SHA-256. Merkle–Damgård construction with Davies–Meyer compression functionĪ 2011 attack breaks preimage resistance for 57 out of 80 rounds of SHA-512, and 52 out of 64 rounds for SHA-256. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |