An authentication code appended to a file that indicates the author of the file. Most digital signatures use public key encryption. A checksum derived from the document is encrypted using the author's private key and attached to the file. If decrypted using the corresponding public key supplied by the author, this will match the recomputed checksum; if decrypted using any other key, it will not. Digital signatures are very important for verifying the source not only of electronic documents but also of software components. See also certificate.