A Provably Secure Threshold Signature Scheme Under Standard Model

Threshold signature could distribute the power of signature,and therefore is more secure than normal single signature.Most threshold signatures have the key-escrow proplem.For the security problem in a novel identity-based threshold signature,a modified threshold signature scheme by using bilinear parings is proposed.In this scheme,the private key generator cooperates with signing users in generating key,thus to prevent PKG from forging signatures.Theoretical analysis shows that the new scheme has the properties of robustness and unforgeability,and compared with the previous scheme,it is safer and with no obvious decrease in efficiency.