Security Analysis And Improvement Of Two Digital Signature Schemes

With the rapid growth of various application requirements in the network environment,information security problems have followed one after another.As the core technology of modern cryptography research,digital signatures ensure the integrity,authentication and non-repudiation of messages in the field of digital communications,and play an extremely important role in the fields of economy,military,politics and science and technology.However,the continuous updating of various network applications has put forward new demands for its security performance,which requires that digital signature schemes need to have more special properties to provide higher security.The identity-based digital signature directly uses the user's identity as the public key,avoiding the problems of certificate generation,storage,and management overhead in the traditional digital signature scheme.Aggregate signature is a "batch" and "compression" technology in the field of digital signatures,which greatly improves the signature verification and transmission efficiency.Certificateless aggregated signatures do not require public key certificates and key escrow,and are widely used in vehicle networks,cloud computing,and distributed systems.This paper focuses on revocable identity-based signatures and certificateless aggregate signatures,analyzes the security flaws of the two signature schemes,and proposes corresponding improvements.The main research contents are as follows:(1)Hung et al.proposed a revocable identity-based signature scheme in the standard model,we pointed out that the scheme is not with strong unforgeability and signing key exposure resistance.To solve these problems,we construct an improved revocable identity-based signature scheme,which can not only effectively revoke users,but also resist signing key exposure resistance attacks.The analysis results show that the new scheme is strong and unforgeable under adaptive identity selection and message attacks,and has high computing performance.(2)Wang Daxing et al.proposed a certificateless aggregate signature scheme for vehicular ad-hoc networks,we through three types of forgery attacks proved this scheme was not have the existentially unforgeable in the random oracle model.To resist these attacks,Proposed an improved certificateless aggregate signature scheme,It's security depends on the computational Diffie-Hellman assumption.The new scheme not only effectively resist coalition attacks.but also has identity anonymity and traceability,which meets the vehicle-mounted communication in a high-speed mobile environment.