Public key Tracing Framework using Blockchain

Context In recent years, instant messaging has become a popular means of communication among users. This has led to an increased amount of data exchange over the network. The exchanged data is usually privacy-sensitive, which makes data protection crucial in such systems. The market leaders (such as Whatsapp and Telegram) aim at mitigating the risk by utilizing end-to-end asymmetric encryption, where all the exchanged data is encrypted with the corresponding public key of users. Despite the utilization of advanced encryption, clients could still be tricked to encrypt data with public keys of attackers instead of their recipients’ keys [5,6]. These attacks, known as Manin-the-Middle (MitM) [4], could lead to the violation of privacy. The weakness lies in the fact that users are incapable of authenticating, or at the very least tracking, their recipients’ public keys over time. Users’ possession of multiple devices (and thus multiple keys) and the possibility of legitimately obtaining new keys (e.g. in case of a device loss) worsen the situation.