File fixity

[1] Fixity checking is the process of verifying that a digital object has not been altered or corrupted.

[2] During transfer, a repository may run a fixity check to ensure a transmitted file has not been altered en route.

Instead, it allows a repository to identify which corrupted files to replace with a clean copy from the producer or from a backup.

In practice, a fixity check is most often accomplished by computing checksum or cryptographic hash function values for a file and comparing them to a stored value or through digital signatures.

[4] File fixity figures prominently in Preservation Metadata: Implementation Strategies (PREMIS), the Government Printing Office's work on the Authenticity of Electronic Federal Government Publications,[5] and fixity checking practices are used by a range of cultural heritage organizations.