In
cryptography
Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or ''-logy, -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of Adversary (cryptography), ...
, a key signature is the result of a third-party applying a cryptographic signature to a representation of a cryptographic key. This is usually done as a form of assurance or verification: If "Alice" has signed "Bob's" key, it can serve as an assurance to another party, say "Eve", that the key actually belongs to Bob, and that Alice has personally checked and attested to this.
The representation of the key that is signed is usually shorter than the key itself, because most public-key signature schemes can only encrypt or sign short lengths of data. Some derivative of the
public key fingerprint
In public-key cryptography, a public key fingerprint is a short sequence of bytes used to identify a longer public key. Fingerprints are created by applying a cryptographic hash function to a public key. Since fingerprints are shorter than the k ...
may be used, i.e. via
hash function
A hash function is any Function (mathematics), function that can be used to map data (computing), data of arbitrary size to fixed-size values, though there are some hash functions that support variable-length output. The values returned by a ...
s.
See also
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Key (cryptography)
A key in cryptography is a piece of information, usually a string of numbers or letters that are stored in a file, which, when processed through a cryptographic algorithm, can encode or decode cryptographic data. Based on the used method, the key ...
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Public key certificate
In cryptography, a public key certificate, also known as a digital certificate or identity certificate, is an electronic document used to prove the validity of a Key authentication, public key. The certificate includes the public key and informati ...
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Key management