Abstract. Chameleon signatures simultaneously provide the properties of nonrepudiation and non-transferability for the signed message. However, the initial constructions of chameleon signatures suffer from the problem of key exposure. This creates a strong disincentive for the recipient to forge signatures, partially undermining the concept of non-transferability. Recently, some specific constructions of discrete logarithm based chameleon hashing and signatures without key exposure are presented, while in the setting of gap Diffile-Hellman groups with pairings. In this paper, we propose the first key-exposure free chameleon hash and signature scheme based on discrete logarithm systems, without using the gap DiffileHellman groups. This provides more flexible constructions of efficient key-exposure free chameleon hash and signature schemes. Moreover, one distinguishing advantage of the resulting chameleon signature scheme is that the property of “message hiding” or “message rec...