We propose an efficient authentication method for secure communication among a set of devices that have a single trusted manager or administrator, with protocols presented for authentication and authenticated key exchange. An example of such a setting would be a set of devices or sensors owned by a single person, including applications such as a smart house or coordinated control systems, with emphasis on the simplicity and efficiency of the protocol. While known techniques can solve this problem, we show how specific properties of our setting can allow our more efficient solution, which is more appropriate for embedded processors with limited computational capabilities. Specifically, a device using our protocol can authenticate itself using only about 15% of the computation required by a standard RSA signature-based authentication. We prove that our scheme is secure under the strong RSA assumption and the computational Diffie-Hellman assumption.