(2) Aiming at the proposed new proxy multi-signature scheme, the overall design of the scheme is elaborated in detail, and the establishment of security parameters, authorization equation, signature flow and implementation process of signature verification are given. The detailed design of the main functional components is given, and the security issues such as unforgeability, verifiability, legitimacy, authentication, non-repudiation and signature control of the scheme are analyzed.

(3) Based on the existing message privacy proxy signature scheme, a forgery attack is proposed, its security vulnerabilities are pointed out, and an improved scheme is given. The improved scheme is more perfect and has the characteristics of strong proxy signature, which can effectively prevent the original signer from forging proxy signature and resist the existing known attacks.