Analysis and Improvement of Threshold Proxy Signature Scheme

This paper presents a(t,n) threshold proxy(c,m) threshold signature scheme.It finds that either the original scheme or two improved schemes are vulnerable to collusion attack and public-key substitute attack.By including the identities of the actual signers in the proxy signature generation phase,it proposes a new threshold proxy threshold signature scheme with the property that the actual signers from the proxy group are identified and traceable.Analysis results show that the scheme can resist the mentioned attacks efficiently.