Paper 2000/068

A Content Certified E-mail Protocol with a Public Mailbox

Tak-Ming Law

Abstract

This short note presents some ideas of the content certified e-mail protocol with a public mailbox. By applying the Diffie-Hellman key exchange style to reflect the agreement between the sender and receiver. The notion of certified e-mail just similar to the certification procedures for regular mails in the real-life post offices. Yet the post office only certifies whether the mail has been sent or received by the appropriate parties, but not its content. This insufficient verification in paper authentication protocols can be easily solved by digital signature schemes. A certified e-mail protocol must have the following security properties: 1. The sender must have some way of proving that the receiver received the mail, should the receiver later try to deny it. 2. The receiver must have some way of proving that the sender did not send the mail, should the sender later try to claim that she did.