Glossary
Cryptographic Hash Function
A hash function is a mathematical operation that converts input data of any length into a fixed-length output (hash); even a minimal change to the input radically changes the hash.
Full Definition
In the context of digital signatures, a hash function (e.g. SHA-256) creates a 'fingerprint' of the document — the hash is signed, not the entire document. This enables efficient signing and integrity verification: if the document changes after signing, the hash no longer matches the signed value and the signature is invalid.
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