The authors first analyze the security of digital certificate identification mechanism,then bring forward a scheme of signature step by step based on multi-agent based on the feature of RAS signature algorithm and the present status of prior secret-share mechanism,which solves both the efficiency problem of off-line signature and the security problem of traditional signature.

The paper realizes all algorithms of prior secret-share protocol, and considers possible problems in each phase of secret-share and presents corresponding settlement scheme.

Practical proactive secret sharing scheme for asynchronous networks with unreliable links;

Only proactive secret sharing can properly protect it.

Security analysis for proactive secret sharing system;

Dynamic analysis and evaluation of the security of a proactive secret sharing system;

Threshold secret sharing is one of the important way to save securely important information and data, proactive secret sharing renews every share periodically without changing the secret.

Then, using verifiable secret sharing and digital signatures, an improved protocol that can resist the sender’s deceive, the receivers’ deceive and tamper attack is proposed.

In this paper,a framework of distributed certificate services for Ad hoc networks is proposed, which is based on RSA digital signature scheme with threshold cryptography and verifiable secret sharing.

Shoup s scheme was improved,and a verifiable threshold RSA signature scheme with verifiable secret sharing was presented.