Abstract
A new formal model of security for proxy signature schemes is presented and a provably secure short proxy signature scheme is proposed from bilinear maps. The proposed proxy signature scheme is based on two short secure signature schemes. Finally, a security proof of the proposed proxy signature scheme is showed by reducing directly the security of the proxy scheme to the security of the two basic signature schemes. The proposed proxy signature scheme has the shortest proxy signatures, the proxy signature generation needs no pairing operation and verification needs just one pairing operation.