Abstract-VANET security is major issue for researcher. Thus Ad-Hoc Networks embrace the Public Key Infrastructure (PKI) and Certificate Revocation Lists (CRLs) for their security purpose. EMAP was presented to overcome the problem of the long delay incurred in checking the revocation status of a certificate using a CRL. From the experimental analysis it was observed that it is resistant to common attacks while performing the authentication techniques. Therefore, EMAP can significantly decrease the message-loss ratio due to message verification delay as compared to the conventional authentication methods employing CRL checking. Thus to further address these issues along with EMAP protocol, new EMAP method is presented called as CEMAP (certificate based EMAP) which is intended to overcome the authentication delay in message processing by reducing the complexity in Authentication process. CEMAP authentication protocol is constructed based on the combination of the new signature scheme and EMAP. The proposed algorithm reduces the delay by 10% than EMAP.