An End-to-End Encrypted Peer-to-Peer Chat System with Self-Sovereign Identity

Today, messaging applications are the most popular medium of communication over the Internet. As their use has grown, different security and privacy concerns have received the attention of users. Users consider what they send with others to be private, tamper-proof and secure without getting exposed to unintended entities. Furthermore, users are concerned whether their data is exposed if the service provider encounters any cyber attack. In this paper, we propose a Self-Sovereign Identity (SSI)-based End-to-End Encrypted Peer-to-Peer (E2EE P2P) chat system that does not rely on any specific provider, enhancing user privacy and security. The system leverages decentralized identifiers (DIDs) to establish secure communication channels using the DIDcomm (DID Communications) protocol, which ensures the privacy of user data. We also introduce a secure file sharing mechanism that ensures that all data, including messages, are stored solely on the user's device, further safeguarding user privacy. The system is developed following the Design Science Methodology, addressing probable threats and satisfying different functional and security requirements. The architecture and its implementation details are discussed with the subsequent use cases and protocol flow. Finally, we analyze different aspects of the system.