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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 ...
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 ...
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.
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 ...
Research on the security analysis of the Whirlpool function however, has revealed that on average, the introduction of 8 random faults is sufficient to compromise the 512-bit Whirlpool hash message being processed and the secret key of HMAC-Whirlpool within the context of Cloud of Things (CoTs).
Identifies which algorithm is used to generate the signature. In the below example, HS256 indicates that this token is signed using HMAC-SHA256. Typical cryptographic algorithms used are HMAC with SHA-256 (HS256) and RSA signature with SHA-256 (RS256). JWA (JSON Web Algorithms) RFC 7518 introduces many more for both authentication and encryption.