A new efficient on-line/off-line threshold signature scheme

It seems that all existing on-line/off-line (threshold) signature schemes based on Shamir-Tauman's paradigm suffer from the key exposure problem of chameleon hashing. In this paper, we firstly propose a new efficient generic on-line/off-line threshold signature scheme without key exposure. Compared with Crutchfield et al.'s scheme, the advantages of our scheme are the lower computation and storage cost in off-line phase and lower communication cost in on-line phase. Meanwhile, we prove our scheme can achieve the desired security notions.