Along with the development of Information Technology, online transactions through Internet have become more popular for the reasons of convenience and efficiency. In order to provide secure and reliable online transactions, an effective electronic payment protocol is crucial. In this paper, we propose a novel electronic payment protocol for digital product transactions with an offline arbiter to achieve fair exchange, automated dispute resolution, customer anonymity, and customer unlinkability. In our protocol a product token is adopted to eliminate the need of key management for digital product decryption in the offline arbiter. In addition, Elliptic Curve Cryptography (ECC)-based self-certified public key is utilized to further reduce computing overheads. According to our analysis, the efficiency of our protocol can be greatly increased in comparison with previous literatures.