Threshold proxy re-signature

The focus of this paper is to design an efficient and secure solution addressing the semi trusted issue in proxy re-signature schemes, i.e., the proxy knows the re-signature key from user A to user B, so he is able to translate any signatures made by user A to user B, which damages the essential requirement ("non-repudiation" property) of proxy re-signature schemes. In this paper, the authors first define the security model for threshold proxy re-signature scheme, and then propose two threshold proxy re-signature schemes based on Ateniese-Hohenberger's and Shao-Cao-Wang-Liang's approach.