Abstract — In this paper, an efficient authentication scheme is proposed which is suitable for low-power mobile devices. It uses an elliptic-curve-cryptosystem based trust delegation mechanism to generate a delegation passcode for mobile station authentication, and it can effectively defend all known attacks to mobile networks including the denial-of-service attack. Moreover, the mobile station only needs to receive one message and send one message to authenticate itself to a visitor’s location register, and the scheme only requires a single elliptic-curve scalar point multiplication on a mobile device. Therefore, this scheme enjoys both computation efficiency and communication efficiency as compared to known mobile authentication schemes. Index Terms — mobile authentication, denial-of-service attack, message en route attack, false base station attack, elliptic-curve cryptosystems. I.