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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]
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.
SHA-1: 160 bits Merkle–Damgård construction: SHA-224: 224 bits Merkle–Damgård construction: 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 ...
SHA-2 basically consists of two hash algorithms: SHA-256 and SHA-512. SHA-224 is a variant of SHA-256 with different starting values and truncated output. SHA-384 and the lesser-known SHA-512/224 and SHA-512/256 are all variants of SHA-512. SHA-512 is more secure than SHA-256 and is commonly faster than SHA-256 on 64-bit machines such as AMD64.
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.
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 ...
The block transformation f, which is Keccak-f[1600] for SHA-3, is a permutation that uses XOR, AND and NOT operations, and is designed for easy implementation in both software and hardware. It is defined for any power-of-two word size, w = 2 ℓ bits. The main SHA-3 submission uses 64-bit words, ℓ = 6.
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