A digital signature (not to be confused with a digital certificate) is an electronic rather than a written signature. It can be used with any kind of message, whether it is encrypted or not, simply so that the receiver can be sure of the sender’s identity and that the message arrived intact. A digital certificate contains the digital signature of the certificate-issuing authority so that anyone can verify that the certificate is real. Additional benefits to the use of a digital signature are that it is easily transportable, cannot be easily repudiated, cannot be imitated by someone else, and can be automatically time-stamped.