The Research Of (t,n) Threshold Signature Scheme Without Trust Part

Digital signature has important applications in the field of information security. As a kind of special digital signature, threshold signature is researched widely based on its important practical value.Most of existing threshold signature schemes with trusted party could be possible to cheat authority, even more there exist some threshold signature schemes without trusted party which are researched in this paper. The author mainly studys the scheme without trust party focusing on resist conspiracy attack threshold signature and forward-security threshold signature. According to existing schemes, the author improves threshold scheme and threshold proxy signature scheme respectively to make it more securely and effectively. The main studying results of this thesis are as follows:(1) The author studies the threshold signature schemes basing on the elliptic curve be aimed at the existing scheme can not resist conspiracy attack, the author provides an improved (t,n)-threshold signature scheme without a trust party, and the correctness and the security analysis are proved. The new scheme does not need to set parameters by a trust party in system initialization phase, and it also can resist conspiracy attack.(2) The author designs a forward-security threshold signature scheme based on the elliptic curve. The author introduces the idea of the forward-security to a new threshold signature scheme based on the elliptic curve, and designs a new scheme. The new scheme without a trust party not only retains the advantages of original signature scheme, but also has a forward-security.(3) The author designs the threshold proxy signature form bilinear pairing. In consideration of good properties of signature scheme from bilinear pairing, the author uses the bilinear pairing to construct a new threshold proxy signature scheme. The new scheme without a trust party has forward-security and it can resist conspiracy attack. In addition, it possesses higher efficiency than the relevant one.