Traditional public key cryptosystem (PKC) requires high maintenance cost for certificate management. Although, identity based cryptosystem (IBC) reduces the overhead of management, it suffers from the drawback of key escrow. Certificate-based cryptosystem solves certificate revocation problem and eliminate third party queries in the traditional PKI. In addition, it also solves the inherent key escrow problem in the IBC. In this paper, we proposed an efficient certificate-based signature and the result shows that the scheme is provable secure against two game attacks of certificate-based signature in the random oracle model. The security is closely related to the difficulty of solving the discrete logarithm problem.