By the mid 1990s, e-mail security became a needed addition to the messaging people already knew. Two protocols emerged as standards: Pretty Good Protection (PGP) and Secure/Multipurpose Internet Mail Extensions (S/MIME). Both offered digital signaturesi which added the capabilities of authentication, non-repudiation, and data integrity. Message encryption added the capabilities of confidentiality and data integrity. For the user this helped ensure two things: First, that only the intended recipient can read the message. Second, that a person reading a message can be assure of the identity of the sender.
