New nonrepudiable threshold proxy signature scheme with known signers

Based on Kim et al.'s threshold proxy signature scheme. Sun proposed an non repudiable threshold proxy signature scheme with known signers. In Sun's sc heme, actual proxy signers cannot deny the signatures they have signed. How ever, his scheme is vulnerable against the conspiracy attack. Any t malicio us proxy signers can collusively derive the secret keys of other proxy sign ers and impersonate some other proxy signers to generate proxy signatures. In this paper, we proposed a new nonrepudiable threshold proxy signature sc heme that overcomes the above weakness. Furthermore, the proposed scheme is more efficient than Sun's in terms of computational complexities and commu nication costs. (C) 2001 Elsevier Science Inc. All rights reserved.