77a8603f_ervation__Library_of_Congress___Definition
[Term] Digital signature [Definition] 
A method to authenticate digital materials that consists of an encrypted digest of the file being signed. The digest is an algorithmically-computed numeric value based on the contents of the file. It is then encrypted with the private part of a public/private key pair. To prove that the file was not tampered with, the recipient uses the public key to decrypt the signature back into the original digest, recomputes a new digest from the transmitted file and compares the two to see if they match. If they do, the file has not been altered in transit by an attacker. See also "Checksum" and "Fixity Check."
NDSA Levels of Preservation Glossary - National Digital Stewardship Alliance - Digital Preservation (Library of Congress)
Definition