Search results
Results From The WOW.Com Content Network
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.
Paul Hsieh's SuperFastHash [1] 32 bits Buzhash: variable XOR/table Fowler–Noll–Vo hash function (FNV Hash) 32, 64, 128, 256, 512, or 1024 bits xor/product or product/XOR Jenkins hash function: 32 or 64 bits XOR/addition Bernstein's hash djb2 [2] 32 or 64 bits shift/add or mult/add or shift/add/xor or mult/xor PJW hash / Elf Hash: 32 or 64 bits
The idea of fuzzy checksum was developed for detection of email spam by building up cooperative databases from multiple ISPs of email suspected to be spam. The content of such spam may often vary in its details, which would render normal checksumming ineffective.
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.
G (key-generator) gives the key k on input 1 n, where n is the security parameter. S (signing) outputs a tag t on the key k and the input string x. V (verifying) outputs accepted or rejected on inputs: the key k, the string x and the tag t. S and V must satisfy the following: Pr [ k ← G(1 n), V( k, x, S(k, x) ) = accepted] = 1. [5]
If R(x) = r n−1 x n−1 + ⋯ + r 1 x + r 0 is any nonzero polynomial modulo 2 with at most t nonzero coefficients, then R(x) is not a multiple of P(x) modulo 2. [Notes 4] If follows that the corresponding hash function will map keys with fewer than t bits in common to unique indices. [3]: 542–543
Cryptographic weaknesses were discovered in SHA-1, and the standard was no longer approved for most cryptographic uses after 2010. 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.
In cryptography, the avalanche effect is the desirable property of cryptographic algorithms, typically block ciphers [1] and cryptographic hash functions, wherein if an input is changed slightly (for example, flipping a single bit), the output changes significantly (e.g., half the output bits flip).