The Research Of Threshold Shared Verification Signature Without Trusted Patry

Secret sharing is an important part of modern cryptography. It is also animportant research direction of the information security. Threshold sharedverification signature means any t verifiers in n participants can cooperate to verifythe validity of the signature, and any fewer than t verifiers can do nothing. Usingsecret sharing technology, threshold shared verification signature has changed themode of traditional single person to verify the signature. It prevents excessiveconcentration of power being abused, which enhances the credibility of theverification side. Therefore, the research of threshold shared verification signaturehas important theoretical significance and broad application prospects.This thesis introduces several typical secret sharing schemes, analyzesshortcomings of existing schemes of threshold shared verification signature indetail. Such as the deception of the authority, and the prior designation of t verifiersin shared verification stage. A threshold shared verification signature scheme isproposed without a trusted party. And this scheme has the following features:(1) Without a trusted party. There is a trusted party in the existing schemes ofthreshold shared verification signature, and dishonest acts of the trusted party willlead to the threshold shared verification signature meaningless. The scheme has notrusted party. All verifier produce the group public key cooperatively, and no oneknows the group private key to verify the signature, which can avoid the authoritydeception.(2) Without prior designated verifier. It needs to determine t verifiers at first inshared verification signature stage in Hsu’s scheme which lack of flexibility. It isno longer needs to specify verifier in advance in the thesis. The combination of anyt and more than t copies of the secret share can complete the signature verification,which improves the flexibility and the availability of the scheme.In Windows XP, a prototype system is implemented by using VC++6.0. Theexperimental results show that the scheme is correct and feasible and has goodsecurity and applicability.At last, a summary and an outlook are given at the end of the thesis.