Privacy-Enhanced Mail (PEM) is an Internet standard that provides for secure exchange of electronic mail. PEM employs a range of cryptographic techniques to allow for confidentiality, sender authentication, and message integrity. The message integrity aspects allow the user to ensure that a message hasn't been modified during transport from the sender. The sender authentication allows a user to verify that the PEM message that they have received is truly from the person who claims to have sent it. The confidentiality feature allows a message to be kept secret from people to whom the message was not addressed.