Self-Generated-Certificate Public Key Cryptography (SGC-PKC), is the enhanced version of Certificateless Public Key Cryptography (CL-PKC). It preserves all advantages of CL-PKC. Similar to CL-PKC, every user is given a partial private key by the KGC and generates his own private key and corresponding public key. In addition, it can defend against the Denial-of- Decryption (DoD) Attack. In this paper, we propose a new approach to construction SGC-PKE scheme that derived from a new application of chameleon hash and give a concrete scheme. It is the first scheme which has flexible public key and reaches Giraults trusted level 3, the same level as is enjoyed in a traditional PKI.