No Author Based Selective Receipt in an Efficient Certified E-mail Protocol

A certified electronic mail protocol must avoid the selective receipt of messages in notification operations. No author based selective receipt is a desired feature for certified electronic mail protocols because the receiver must accept or reject the message before the identity of the sender is revealed. We present a certified e-mail protocol, based in our previous protocol presented in the International Security Workshop 2000, which avoids selective receipt. The modified protocol does not use the signature of the sender in the first step of the protocol and avoids temporally the identification of the sender. However, even without this signature, the protocol presents a dispute resolution system that avoids unfair situations. The result is a fair, asynchronous and efficient protocol. Moreover we have evaluated the role of the TTP in the fair exchange protocol, showing that the incorrect behavior of the TTP can be demonstrated in all cases, so the TTP is verifiable.