The Research And Realization Of Threshold Signature Withstanding Conspiracy Attack

Cryptography plays an important role in protecting information security. Threshold secret sharing scheme is one of the most important components of cryptography; it improves system's security and robustness by distributing the responsibility so that it has good application value in storing important information, secret key management, group signature and so on.(t,n) threshold signature scheme is a special digital signature, it is a combiner of (t,n) secret sharing scheme and digital signature. In this thesis, we introduce the creation and development of secret sharing scheme and threshold signature scheme, detailed analyzing some classic threshold signature schemes which can withstand conspiracy attack. To deal with the problems and deficiencies of these schemes, we provide a new threshold scheme against conspiracy attack. The scheme has properties as follow:1. This scheme can complete threshold signature while do not expose secret key (signature key). Group secret key is a secret to all participants, including signers and signature combiner, so the signature key can be used repeatedly.2. In order to withstand conspiracy attack, the scheme utilizes two ways: (1) adding random number and time stamp to prevent attackers recover the secret key, at the same time prevent attack of disrupting protocol; (2) using zero knowledge proof to confirm that the signer has right secret key, so that it prevents the attacker forging signature directly.In Windows XP, we use VC++ 6.0 design a prototype of this scheme. The result shows that this scheme is correct and feasible, meantime can withstand conspiracy attack, and has good security and robustness.