Cryptography
Message Authentication Code (MAC)
Also known as: MAC, Cryptographic checksum
Definition
A short symmetric-key tag that authenticates a message and detects tampering, computed and verified with the same shared secret.
Examples
- HMAC-SHA-256 is used to authenticate AWS Signature Version 4 requests.
- Poly1305 authenticates ciphertext in the ChaCha20-Poly1305 AEAD used by TLS 1.3.
Related terms
HMAC
A keyed Message Authentication Code construction built on top of a cryptographic hash function, defined in RFC 2104 and FIPS 198-1.
Cryptographic Hash Function
A deterministic one-way function that maps arbitrary-length input to a fixed-length digest, designed to be collision-, preimage-, and second-preimage-resistant.
Digital Signature
A public-key cryptographic mechanism that proves the authenticity, integrity and non-repudiation of a message or document.
Symmetric Encryption
An encryption scheme in which the same secret key is used for both encryption and decryption, offering high speed and strong confidentiality when the key is shared securely.
ChaCha20
A modern stream cipher designed by Daniel J. Bernstein, using a 256-bit key and 96-bit nonce, widely deployed alongside Poly1305 as the AEAD ChaCha20-Poly1305.
TLS (Transport Layer Security)
TLS (Transport Layer Security) — definition coming soon.