Public key replacement and universal forgery of SCLS scheme

certicatelesscryptography eliminates the need of certicates in the PKI and solves the inherent key escrow problem in the ID-based cryptography. Recently, Du and Wen proposed a short certicateless signature scheme (SCLS) without MapToPoint hash function, and the signature size is short enough with only half of the DSA signature. In this paper, after the detailing the formal of certicateless signature scheme, we show that the Du-Wen's short certicateless signature scheme is insecure that is broken by a type-I adversary who has the ability in replacing users' public keys and accessing to the signing oracles, and also cannot resist on the universal forgery attack for any third user.