An efficient nonrepudiable threshold proxy signature scheme with known signers

A (t,n) threshold proxy signature scheme allows t or more proxy signers fro m a designated group of n proxy signers to sign messages on behalf of an or iginal signer. A threshold proxy signature scheme with the nonrepudiation p roperty is a scheme with the capability that any verifier can identify the proxy group which is responsible for a proxy signature, while the proxy gro up cannot deny. So far, there have been two threshold proxy signature schem es proposed. Of these, Kim's scheme is nonrepudiable, but Zhang's scheme is not. Ln these two schemes, the t proxy signers from the group who actually sign the message are unknown and unidentified. This is very inconvenient f or auditing purposes. For the responsibility of the actual signers and the traceability of adversarial signers, it is sometimes necessary to identify who the actual signers are. In this article, we propose the nonrepudiable t hreshold proxy signature scheme with known signers which is a nonrepudiable threshold proxy signature scheme with the property that the actual signers from the proxy group are known and identified. (C) 1999 Elsevier Science B .V. All rights reserved.