A Secure Proxy Signature Scheme in Bilinear Group

The paradigm of proxy signature is one of important digital signatures. In a proxy signature scheme, it allows an entity to delegate signing capabilities to other participants so that they can sign on behalf of the entity. Proxy signatures are useful to design cryptographic protocols, however, there are only few provable secure proxy signature schemes. In this paper, we propose a new provably secure proxy signature scheme based on Gap Diffie-Hellman (GDH) group. Though many other proxy signature schemes have been proposed, the construction method in our paper is easy and simple, which utilize the technique of bilinear map and traditional certificate-based signature scheme. Thus, the resulting scheme can be formally proved based on these two notions. Furthermore, we also give its security analysis and security definitions. The scheme has low computational cost of the signature generation. So it is very suitable for low-bandwidth environment.