Research on Two-Party Cooperative Aigis-sig Digital Signature Protocol

The digital signature scheme is essential for electronic commerce and e-government security authentication. With the rapid advancement of mobile internet technologies, safe key storage in mobile terminals has become a new challenge. To solve the leak of the signature private key, a method for generating a two-party cooperative signature has been proposed. That is, each participant generates the signature secret key and shares it with the other after which the signature is generated interactively. The method is robust because one party cannot recover the secret key, which not only guarantees the correctness of the signature but can resist the security implications caused by the corruption of a single mobile terminal. Considering the threat from quantum computing technology to conventional public-key cryptographic algorithms, in this paper, the lattice-based post-quantum digital signature algorithm, Aigis-sig, published in the international conference on public-key cryptography is discussed. Furthermore, the two-party Aigis-sig signature protocol is proposed. The protocol contains two sub-protocols: distributed secret key generation and collaborative signing protocol. In addition, the homomorphic encryption scheme is introduced in the protocol to ensure that the intermediate of the protocol does not reveal the private key information. The evaluation demonstrates that the protocol has correctness and feasibility. In the case that both parties are honest, the cooperative signature is existential unforgeability against the chosen-message attack.