{{short description, Data used to identify or verify the content of a file
In
computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both hardware and software. Computing has scientific, e ...
, a file signature is data used to identify or verify the contents of a file. In particular, it may refer to:
* File magic number: bytes within a file used to identify the format of the file; generally a short sequence of bytes (most are 2-4 bytes long) placed at the beginning of the file; see list of file signatures
* File checksum or more generally the result of a
hash function
A hash function is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called ''hash values'', ''hash codes'', ''digests'', or simply ''hashes''. The values are usually u ...
over the file contents: data used to verify the integrity of the file contents, generally against transmission errors or malicious attacks. The signature can be included at the end of the file or in a separate file.