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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 simplest such pairwise independent hash function is defined by the random key, key = (a, b), and the MAC tag for a message m is computed as tag = (am + b) mod p, where p is prime. More generally, k -independent hashing functions provide a secure message authentication code as long as the key is used less than k times for k -ways independent ...
HKDF-Extract takes "input key material" (IKM) such as a shared secret generated using Diffie-Hellman, and an optional salt, and generates a cryptographic key called the PRK ("pseudorandom key"). This acts as a "randomness extractor", taking a potentially non-uniform value of high min-entropy and generating a value indistinguishable from a ...
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.
HMAC-based one-time password (HOTP) is a one-time password (OTP) algorithm based on HMAC. It is a cornerstone of the Initiative for Open Authentication (OATH). HOTP was published as an informational IETF RFC 4226 in December 2005, documenting the algorithm along with a Java implementation. Since then, the algorithm has been adopted by many ...
HMAC: KMAC: arbitrary based on Keccak MD6: 512 bits Merkle tree NLFSR: One-key MAC (OMAC; CMAC) PMAC (cryptography) Poly1305-AES: 128 bits nonce-based SipHash: 32, 64 or 128 bits non-collision-resistant PRF: HighwayHash [16] 64, 128 or 256 bits non-collision-resistant PRF: UMAC: VMAC
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 ...
RFC 7677, SCRAM-SHA-256 and SCRAM-SHA-256-PLUS: Simple Authentication and Security Layer (SASL) Mechanisms; RFC 7804, Salted Challenge Response HTTP Authentication Mechanism; RFC 8600, Using Extensible Messaging and Presence Protocol (XMPP) for Security Information Exchange; RFC 8621, The JSON Meta Application Protocol (JMAP) for Mail