A Non-repudiable Protocol for Secure Messaging

As Oppliger stated, secure messaging refers to the ability to provide data confidentiality, data integrity, data origin authentication, and non-repudiation of origin services for email. It is very important but poorly developed and has very limited application. We propose an email protocol assures non-repudiability which means that if the email is successfully sent, the sender cannot deny she/he has actually sent the mail and the recipient cannot deny she/he has actually received it. The protocol uses an efficient RSA-based convertible signature.