An Efficient Verifiably Encrypted Signature from Weil Pairing

Abstract

A verifiably encrypted signature (VES) is a kind of very useful signature in online optimistic contract signing protocols. VES enables fair exchange between participants in signing protocols, which can allow the verifier to test that a given ciphertext is the encryption of a signature on a given message. In this paper, a novel efficient VES scheme which makes use of Weil pairing is proposed. The proposed signature scheme can provide good security properties such as validity, unforgeability, and opacity. We analyze the security and efficiency of the proposed scheme. Compared with the previous schemes, the proposed VES schemes is more efficient in terms of computational cost. In particular, the total computational cost of the three important phases of VES signing, VES verification, and adjudication in our scheme is decreased by at least 4M, where M indicates a scalar point multiplication. In addition, the signature size in our scheme is reduced to half of the size used in the previous schemes.