Abstract— An important issue in mobile commerce (mcommerce) is to exchange digital data between two distributed parties in an efficient and fair manner. In this paper, a lightweight stand-alone and setup-free verifiably committed signature based on Schnorr signature scheme which aims to achieve efficiency and fairness for m-commerce is proposed. The idea behind of our construction is to encrypt the salt of a partial signature rather than to encrypt the whole partial signature. As a result, our construction is more efficient and thus more suitable for mobile environment compared with the best results in the literature. We further show that our scheme is provably secure in the random oracle model assuming that the Schnorr’s signature scheme is secure against adaptive chosen message attack and Paillier’s encryption scheme is one-way.