Secure Hash Algorithm (SHA)¶
Secure Hash Algorithm, or SHA, is a family of cryptographic hash functions used to turn data into a fixed-length string called a hash or digest.
Key properties
Deterministic: same input gives the same output
One-way: it is not possible to go back to the original data, unless may be with brute-force or rainbow tables
Collision resistant: it is hard to find two inputs with the same hash
Fast to compute
Common SHA versions
SHA-1: a 160-bit hash. It is now considered insecure and should not be used anymore
SHA-2:
. SHA-224 . SHA-256 (very common) . SHA-384 . SHA-512
SHA-3: future version
The SHA hashes re commonly used for password hashing and storage (although it is replaced by more modern methods, like bcrypt), file integrity check, signature, git commits (SHA-1).
<?php
// recommended SHA256 for password
password_hash($password, PASSWORD_DEFAULT);
// raw SHA256
echo hash('sha256', 'The quick brown fox jumped over the lazy dog.');
?>
See also SHA1.
