Security Analysis of A Proxy Signature Scheme Based on the Elliptic Curve Cryptosystem

摘要

Proxy signature allows an original signer to delegate her/his signing capability to a proxy signer so that the proxy signer can sign messages on behalf of the original signer. Based on elliptic curve, one can obtains better efficiency and security compared to conventional proxy signatures. Recently, Wang et al's proposed a proxy signature and a proxy blind signature scheme based on ECDLP. This paper shows that Wang et al's proxy signature scheme do not satisfy the strong unforgeability properties and presents an original signer forgery attack on their scheme by updating the original signer's PKI certificate. At the end, an improved scheme and corresponding security analysis is proposed.