Cryptography
SHA-1
Also known as: Secure Hash Algorithm 1, FIPS 180-1
Definition
A cryptographic hash function producing a 160-bit digest, designed by the NSA in 1995 and now considered broken for collision resistance.
Examples
- Git uses SHA-1 to identify commits and objects (with a transition to SHA-256 underway).
- Older X.509 certificates signed with SHA-1, deprecated by browsers since 2017.
Related terms
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.
MD5
A 128-bit cryptographic hash function designed by Ron Rivest in 1992; now broken — practical collisions are trivial and it must not be used for any security-sensitive purpose.
SHA-256
A 256-bit cryptographic hash function from the SHA-2 family, widely used for digital signatures, TLS, blockchains, and integrity verification.
SHA-3
A family of hash functions based on the Keccak sponge construction, standardized by NIST as a structurally different alternative to SHA-2.
HMAC
A keyed Message Authentication Code construction built on top of a cryptographic hash function, defined in RFC 2104 and FIPS 198-1.
Digital Signature
A public-key cryptographic mechanism that proves the authenticity, integrity and non-repudiation of a message or document.