A novel verifiably encrypted signature scheme without random oracle

Verifiably encrypted signature is a extended signature type and plays an important role in the constructing optimistic fair exchange. In the work, we propose a novel verifiably encrypted signature scheme without random oracles, and show that the security of the scheme is based on the difficulty of solving the Chosen-Target-Inverse-CDH with square problem. By comparing our scheme with Boneh et al scheme and S.Lu et al scheme, we show that our proposed scheme has the following advantages: (1) short signature size, only 320 bits; (2)low computation, only 2 pairing operations are needed in the phase of producing and verifying verifiably encrypted signature, respectively. (3)simplification-ability, the creation of verifiably encrypted signature is able to be completed in a logic step.