digital signature
digital signatures

    Extra data appended to a message which
   identifies and authenticates the sender and message data using
   public-key encryption.

   The sender uses a one-way hash function to generate a
   hash-code of about 32 bits from the message data.  He then
   encrypts the hash-code with his private key.  The receiver
   recomputes the hash-code from the data and decrypts the
   received hash with the sender's public key.  If the two
   hash-codes are equal, the receiver can be sure that data has
   not been corrupted and that it came from the given sender.

   (1995-02-07)