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SHA-2: A family of two similar hash functions, with different block sizes, known as SHA-256 and SHA-512. They differ in the word size; SHA-256 uses 32-bit words where SHA-512 uses 64-bit words. There are also truncated versions of each standard, known as SHA-224, SHA-384, SHA-512/224 and SHA-512/256. These were also designed by the NSA.
In cryptography and computer security, a length extension attack is a type of attack where an attacker can use Hash(message 1) and the length of message 1 to calculate Hash(message 1 ‖ message 2) for an attacker-controlled message 2, without needing to know the content of message 1.
SHA-0: 1993 NSA: SHA-0: SHA-1: 1995 SHA-0: Specification: SHA-256 SHA-384 SHA-512: 2002 SHA-224: 2004 SHA-3 (Keccak) 2008 Guido Bertoni Joan Daemen Michaël Peeters Gilles Van Assche: RadioGatún: Website Specification: Streebog: 2012 FSB, InfoTeCS JSC RFC 6986: Tiger: 1995 Ross Anderson Eli Biham: Website Specification: Whirlpool: 2004 Vincent ...
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. [3] [4] 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.
The data produced in the previous step is hashed with a cryptographic hash function such as SHA-1 or SHA-2. If desired, the hash function output can be truncated to provide a shorter, more convenient fingerprint. This process produces a short fingerprint which can be used to authenticate a much larger public key.
Using SHA-1 as a hash function, the password is stretched into a 128-bit key 50,000 times before opening the document; as a result, the time required to crack it is vastly increased, similar to PBKDF2, scrypt or other KDFs. [citation needed] Office 2010 employed AES and a 128-bit key, but the number of SHA-1 conversions doubled to 100,000. [4]
BLAKE repeatedly combines an 8-word hash value with 16 message words, truncating the ChaCha result to obtain the next hash value. BLAKE-256 and BLAKE-224 use 32-bit words and produce digest sizes of 256 bits and 224 bits, respectively, while BLAKE-512 and BLAKE-384 use 64-bit words and produce digest sizes of 512 bits and 384 bits, respectively.
The wide-pipe hash construction. The intermediate chaining values have been doubled. Due to several structural weaknesses of Merkle–Damgård construction, especially the length extension problem and multicollision attacks, Stefan Lucks proposed the use of the wide-pipe hash [11] instead of Merkle–Damgård construction.