Remarks on the security of the strong proxy signature scheme with proxy signer privacy protection

摘要

In 1996, Mambo et al. introduced the proxy signature scheme for digital applications to delegate the signing capability to a proxy signer. Various constructions were made to devise a strong nondesignated proxy signature scheme. In 2002, Shum and Wei proposed an extended scheme to hide the identity of the proxy signer. A Trusted Authority (TA) can reveal the proxy signer's identity if required. In this paper we show some possible attacks on this scheme.