Cryptanalysis of Huang–Chang partially blind signature scheme

Abstract

Partially blind signature is an extension of blind signature that allows a signer to sign a partially blinded message that include pre-agreed information such as expiry date or collateral conditions in the resulting signatures. It is more useful than blind signature in many applications, such as electronic cash (e-cash) system. Recently, Huang and Chang proposed a new design of efficient partially blind signature scheme. However, in this paper, we show that Huang–Chang partially blind signature scheme is not secure, this scheme does not meet the basic property of a partially blind signature, partial blindness: a malicious user (requester) can prepare a special public information a′ and then remove the original information a from the signer’s signature to obtain a signature with this special information.