Provably secure identity based signature without trusted PKG in the standard model

Most of ID-based signature schemes without trusted PKG are secure in the random oracle model. Design of ID-based signature schemes without trusted PKG which are efficient and provably secure in the standard model is suitable for applications. In this scheme, PKG is prevented from forging a legal user´s signature because it only generates partial private key. The scheme is existentially unforgeable against adaptive chosen message attacks under the computational Diffie-Hellman assumption in the standard model. Our scheme not only eliminates the inherent key escrow problem but also has the property of Traceability.