9.6     Signature algorithm

A signature algorithm is an encryption technique that is used in the process of creating electronic signatures. A signature algorithm always encrypts the hash value; see section "How is an electronic signature created?" in chapter 9.5. Either only the hash value is encrypted or the entire file on which the hash value was calculated is encrypted, including the hash value itself. The algorithm catalogue of the BSI (Bundesamt für Sicherheit in der Informationstechnik - translates to Federal Office for Information Security) lists all algorithms that are suited for creating hash values and for encryption during the creation of electronic signatures.

Please mind that encrypting hash value and file with a signature algorithm does not protect the content data your file. The signed file contains, among other content, the public key that must be used to decrypt the signature in order to validate the signature. Encrypting file to protect its content data is explained in chapter 9.4.