Improving Email Trustworthiness Through Social-Group Key Authentication

The increasing use of email for phishing and unsolicited marketing has reduced the trustworthiness of email as a communication medium. Sender authentication is a known defense against these attacks. Existing proposals for sender authentication either require infrastructural support or break compatibility with existing email infrastructure. In accordance with the end-to-end principle, authentication is implemented at the mail client by executing previously proposed Byzantine fault tolerant public key authentication protocol as an overlay on top of the mail transport protocol.