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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.
The following tables compare general and technical information for a number of cryptographic hash functions. See the individual functions' articles for further information. This article is not all-inclusive or necessarily up-to-date. An overview of hash function security/cryptanalysis can be found at hash function security summary.
In Excel and Word 95 and prior editions a weak protection algorithm is used that converts a password to a 16-bit verifier and a 16-byte XOR obfuscation array [1] key. [4] Hacking software is now readily available to find a 16-byte key and decrypt the password-protected document. [5] Office 97, 2000, XP and 2003 use RC4 with 40 bits. [4]
SHA-3 (Secure Hash Algorithm 3) is the latest [4] member of the Secure Hash Algorithm family of standards, released by NIST on August 5, 2015. [5] [6] [7] Although part of the same series of standards, SHA-3 is internally different from the MD5-like structure of SHA-1 and SHA-2.
SHA-256: 256 bits Merkle–Damgård construction: SHA-384: 384 bits Merkle–Damgård construction: SHA-512: 512 bits Merkle–Damgård construction: SHA-3 (subset of Keccak) arbitrary sponge function: Skein: arbitrary Unique Block Iteration: Snefru: 128 or 256 bits hash Spectral Hash: 512 bits wide-pipe Merkle–Damgård construction Streebog ...
Algorithm and variant Output size (bits) Internal state size (bits) Block size (bits) Rounds Operations Security against collision attacks (bits) Security against length extension attacks
For example, SHA-256 operates on 512-bit blocks. The size of the output of HMAC is the same as that of the underlying hash function (e.g., 256 and 512 bits in the case of SHA-256 and SHA3-512, respectively), although it can be truncated if desired. HMAC does not encrypt the message.
The NIST hash function competition was an open competition held by the US National Institute of Standards and Technology (NIST) to develop a new hash function called SHA-3 to complement the older SHA-1 and SHA-2. The competition was formally announced in the Federal Register on November 2, 2007. [1] "