Study Signature Threshold

Now we are in the information times, with the Internet’s development and popularity, we can share all kinds of information. However, these information is open and can be stealed, fraud, cheat, and destroyed easily by the illegal people with the purpose of getting some interest. It is important to ensure the safety of these opened information by using some cryptography ways.Compared with hand-writing signature in the real world, digital signature plays a great role in electrical world. It is good in the signing of the contract, the proof of document as well as in the other electrical business. Moreover, the majority of countries have already accepted as it has legal effect.In the traditional signature, the signature power is more centralized. To solve above problems and scattered the power, the (t,n) threshold signature appeared, which applies secret sharing knowledge into the digital signature scheme. In this model, t members produce the partial signature by using the personal secret keys, then the specified member compose these signatures into the threshold signature. The verifier can check it with the group’s public key while the signature is given. Of course, all the people can’t form and forge the legal signature without the t member’s cooperation or less them. In this paper, we pay more attention on a threshold signature scheme without a trusted party. Besides, it focus on the problem of conspiracy attack in the threshold signature. The main contents are as follows:In some special cases, as an authority can be trusted by all members does not always exist because of conflict interest or the restriction of some applied environment. A new threshold signature scheme without a trusted party was produced based on wang-li scheme after analyzing WLC threshold signature scheme with a trusted party. It can not only resist conspiracy attacks and forgery attacks, but also provide the anonymity and traceability, so this scheme is useful and value in some applications.To solve the conspiracy attacks in the threshold signature scheme, a threshold signature scheme for conspiracy attack immune was given in this paper. It can not only resist conspiracy attacks and forgery attacks essentially, but also protect the personal secret information by applying message recovery equation, thus this scheme is more safety and more useful.