Privacy-preserving offline mobile payment protocol based on NFC

Nowadays, more and more people use mobile phones as payment devices. Mobile payments are making the way of life more convenient. However, when they decide to use mobile phones for payment, their privacy concerns can outweigh benefits. This paper proposes a new privacy-preserving offline mobile payment protocol based on NFC. In our scheme, a group signature is employed to provide unlinkability of transactions. Compared with ACJT group signature scheme, our scheme is more secure and efficient. Since there are fewer computations at the payment phase, the efficiency of the group signature is improved. Moreover, ACJT scheme is not secure enough. In ACJT scheme, the forgery group signature can be verified by the verifier but the group manager cannot open the group signature to know who signs the message. Our scheme is well designed to accomplish all security and privacy requirements encompassing anonymity, unlinkability, unforgeability, and the prevention of replay attacks.