A Secure Proxy Verifiably Encrypted Signature Scheme

A verifiably encrypted signature can convince the verifier that a given cipher-text is the encryption of a signature on a given message. It is often used as a building block to construct optimistic fair exchange. In this paper, we propose a new concept: proxy verifiable encryption signature scheme, by combining proxy signature with verifiable encryption signature. And we formalize security model of the scheme and show that the scheme is secure in the random oracle model. The security of the scheme is related to Computational Diffie-Hellman problem.