Design and Implementation of a Cloud-based Collaborative Signature System for Two Parties Based on SM2

In applying the collaborative signature protocol to intelligent mobile terminals, problems include low efficiency, lack of optimization based on national cryptographic algorithms, and imperfect keymanagement systems. A cloud-based collaborative signature system based on SM2 is proposed to address this. The system comprises a cloud-side cryptographic module and a mobile intelligent terminal cryptographic module. It ensures the security of sensitive data during the signature process and the legality of the signature result by optimizing the private key splitting scheme and designing secure management techniques for private keys on intelligent mobile terminals. The collaborative signature efficiency is improved through independently developed data preprocessing techniques and SM2 fast signature methods. In addition, a keyrecovery plan is proposed to enhance the system's robustness in the key management system. Experimental results show that the collaborative signature system is superior to similar systems in security and is not compromised in efficiency. The system has already met the level 2 requirements of the “GM/T 0028–2014 Cryptographic Module Security Requirements” and has great potential for market application.