In IOT environments, the device joining of a service group is flexible and quick and a device usually does not has a powerful computation and storage capacity. In this paper, in order to provide a secure service framework in the IOT environments, we propose an efficient authentication and service key agreement scheme. Our proposed scheme can satisfy the nice properties including (1) flexible shared group service keys agreement, (2) low communication and computation cost, (3) mutual authentication, (4) session key agreement, (5) dynamic participation, and (6) no time synchronization problem. Also our scheme can achieve the security requirements including mutual authentication and preventing all various well-known attacks.