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hash function

Turns any data into a short fingerprint; no key, so anyone can recompute it.

A cryptographic hash function such as SHA-256 maps input to a fixed-size digest such that any change alters it; with no key, it detects accidental change only.

Examples

  • SHA-256 turns a firmware image into a 32-byte fingerprint; changing one byte changes the fingerprint.

  • A hash alone doesn't stop an attacker, who can change the data and simply recompute the SHA-256.

See also

message authentication code digital signature authenticated encryption
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