Efficient leakage-resilient blind and partially blind signatures

The techniques of the blind and partially blind signatures play an important role in numerous applications, most prominently in electronic voting and electronic cash. In this paper, we first present formal definitions of leakage-resilient blind and partially blind signatures. Subsequently, we propose an efficient leakage-resilient blind signature scheme and an efficient leakage-resilient partially blind signature scheme in the continual leakage model. The proposed leakage-resilient blind signature scheme is the first protocol which is secure even in a setting where the adversary may obtain leakage information on the signer's or user's internal state, including secret key and the randomness. However, in the only known leakage-resilient blind signature scheme which was proposed by Ruckert, the adversary is given the leakage information only about the signer's secret key. The proposed partially blind signature scheme is the first leakage-resilient partially blind signature scheme. Also, we analyse their security and efficiency in the generic bilinear group model.