A Protocol for Authenticated Anonymous Communications by Post-Quantum Cryptography and Smart Contracts

Security of communications is a foundation for interactions in the cyber space.  Recent advances in the field of quantum computing has attracted attentions to quantum attacks. Post-quantum cryptography is a relatively new field of research and few post-quantum protocols have been proposed for secure communications. In particular, authentication of the two communicating peers while preserving their privacy and anonymity is a real challenge. In this paper, we propose a comprehensive protocol for secure authentication, key agreement, and message encryption which is resistant to quantum attacks. We use the blockchain technology and a smart contract for authentication, and the double-ratchet protocol for end-to-end encryption. Our initial key agreement uses post-quantum cryptography which brings a high level of security to our protocol. We store public keys on a cloud storage for saving costs but authenticate them using smart contracts. Our analysis of the proposed protocol demonstrates our superiority from privacy, security, and performance aspects in comparison to the related works.Security of communications is a foundation for interactions in the cyber space.  Recent advances in the field of quantum computing has attracted attentions to quantum attacks. Post-quantum cryptography is a relatively new field of research and few post-quantum protocols have been proposed for secure communications. In particular, authentication of the two communicating peers while preserving their privacy and anonymity is a real challenge. In this paper, we propose a comprehensive protocol for secure authentication, key agreement, and message encryption which is resistant to quantum attacks. We use the blockchain technology and a smart contract for authentication, and the double-ratchet protocol for end-to-end encryption. Our initial key agreement uses post-quantum cryptography which brings a high level of security to our protocol. We store public keys on a cloud storage for saving costs but authenticate them using smart contracts. Our analysis of the proposed protocol demonstrates our superiority from privacy, security, and performance aspects in comparison to the related works.