Security

A cryptographic hash maps any input to a fixed-length digest. That makes it useful for integrity checks and for storing password verifiers, but the security properties differ: fast hashes such as SHA-256 are designed for integrity and are unsuitable for passwords, while bcrypt, scrypt and Argon2 are deliberately slow and memory-hard.

The entries state the output size, the collision and preimage assumptions, and the correct use of each function. A hash is not encryption and cannot be reversed; when a page says “hash a password”, the choice of algorithm and its parameters matter more than the digest length.