ID-based public key cryptography can be a good alternative for certificate-based public key setting

especially when efficient key management and moderate security are required.This paper proposes a primitive called mixed verifiably encrypted signature scheme (MVESS) and presents an efficient MVESS based on the ID-based signature scheme due to Cheon

et.al

.Then

we provide some theoretical discussions for the security model for MVESSs

and show that our new scheme can be proven to secure with the hardness assumption of the computational Diffie-Hellman problem of pairings in the random oracle model.Our new scheme can be used as blocks to build efficient ID-based optimistic fair signature exchange protocols

which can be widely used in signing digital contracts

e-payment and other electronic commerce.