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Mask generation functions, as generalizations of hash functions, are useful wherever hash functions are. However, use of a MGF is desirable in cases where a fixed-size hash would be inadequate. Examples include generating padding, producing one-time pads or keystreams in symmetric-key encryption, and yielding outputs for pseudorandom number ...
Example of a Key Derivation Function chain as used in the Signal Protocol.The output of one KDF function is the input to the next KDF function in the chain. In cryptography, a key derivation function (KDF) is a cryptographic algorithm that derives one or more secret keys from a secret value such as a master key, a password, or a passphrase using a pseudorandom function (which typically uses a ...
EAX mode (encrypt-then-authenticate-then-translate [1]) is a mode of operation for cryptographic block ciphers. It is an Authenticated Encryption with Associated Data algorithm designed to simultaneously provide both authentication and privacy of the message (authenticated encryption) with a two-pass scheme, one pass for achieving privacy and one for authenticity for each block.
The sponge construction for hash functions. P i are blocks of the input string, Z i are hashed output blocks. In cryptography, a sponge function or sponge construction is any of a class of algorithms with finite internal state that take an input bit stream of any length and produce an output bit stream of any desired length. Sponge functions ...
For this description, the following functions and operators are used: Head (data, a): returns the first a bits of the 'data' string. Tail (data, a): returns the last a bits of the 'data' string. Encrypt (K, data): use the underlying block cipher in encrypt mode on the 'data' string using the key K.
Password is the master password from which a derived key is generated; Salt is a sequence of bits, known as a cryptographic salt; c is the number of iterations desired; dkLen is the desired bit-length of the derived key; DK is the generated derived key; Each hLen-bit block T i of derived key DK, is computed as follows (with + marking string ...
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.
Key stretching algorithms depend on an algorithm which receives an input key and then expends considerable effort to generate a stretched cipher (called an enhanced key [citation needed]) mimicking randomness and longer key length. The algorithm must have no known shortcut, so the most efficient way to relate the input and cipher is to repeat ...