Editing Padding (cryptography) (section)

===Hash functions===
Most modern [[cryptographic hash function]]s process messages in fixed-length blocks; all but the earliest hash functions include some sort of padding scheme. It is critical for cryptographic hash functions to employ termination schemes that prevent a hash from being vulnerable to [[length extension attack]]s.

Many padding schemes are based on appending predictable data to the final block. For example, the pad could be derived from the total length of the message. This kind of padding scheme is commonly applied to hash algorithms that use the [[Merkle–Damgård construction]] such as [[MD5|MD-5]], [[SHA-1]], and [[SHA-2|SHA-2 family]] such as SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and SHA-512/256<ref name="FIPS_180-4">{{cite web |last1=NIST |title=FIPS 180-4 Secure Hash Standard (SHS) |url=https://csrc.nist.gov/csrc/media/publications/fips/180/4/final/documents/fips180-4-draft-aug2014.pdf |publisher=NIST}}.</ref>