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HMAC-SHA1 generation. In cryptography, an HMAC (sometimes expanded as either keyed-hash message authentication code or hash-based message authentication code) is a specific type of message authentication code (MAC) involving a cryptographic hash function and a secret cryptographic key.
In order to sign this new message, typically the attacker would need to know the key the message was signed with, and generate a new signature by generating a new MAC. However, with a length extension attack, it is possible to feed the hash (the signature given above) into the state of the hashing function, and continue where the original ...
ClientKey = HMAC(SaltedPassword, 'Client Key') ServerKey = HMAC(SaltedPassword, 'Server Key') ClientProof = p = ClientKey XOR HMAC(H(ClientKey), Auth) ServerSignature = v = HMAC(ServerKey, Auth) where the XOR operation is applied to byte strings of the same length, H(ClientKey) is a normal hash of ClientKey. 'Client Key' and 'Server Key' are ...
PRF is a pseudorandom function of two parameters with output length hLen (e.g., a keyed HMAC) 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
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 is a simple key derivation function (KDF) based on the HMAC message authentication code. [ 1 ] [ 2 ] It was initially proposed by its authors as a building block in various protocols and applications, as well as to discourage the proliferation of multiple KDF mechanisms. [ 2 ]
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 ...
NIST claims that each of the four (revised to three) DBRGs are "backtracking resistant" and "prediction resistant". The former is the common notion of "forward secrecy" of PRNGs: in the event of a state compromise, the attacker cannot recover historical states and outputs.