TURMS: A Non-invasive Certified Email System

The omni-presence of the Internet in society today determined an explosive growth for online transactions. However, due to lack of security services such as data secrecy, authentication and integrity, Internet does not provide all the guarantees that a business communication tool should. In this context, protocols to facilitate secure and fair electronic exchange and certified electronic delivery are essential. Many solutions were proposed to the fair exchange and/or the certified email problems. Most of these solutions require a trusted third party (TTP) as an arbitrator. In this report we present a non-invasive certified email system which provides confidentiality and fairness, while making use of a TTP in an optimistic way. The fair exchange protocol implemented by this system, guarantees that the email recipient gets the content of the mail if and only if the sender of the mail receives a proof-of-receipt. The proof-of-receipt is the digital signature of the mail recipient, on the mail content. In our protocol, the part that can cheat the fair-exchange is the recipient, therefore in case of dispute the part soliciting TTP’s arbitration, is the sender of the message, the recipient not being involved in the arbitration process.