Wireless Machine to Machine (M2M) communications enable ubiquitous sensing, controlling, and acting via sensors, actuators, and actors. Reliability and security are of foremost importance in wireless M2M systems. A simple, target distinguishing attack can result in M2M’s failure. This paper presents a RelIable and SEcure scheme, RISE, which is a package of policies that guarantee the reliability of data (including sensor reports and actuator instructions) and devices (including sensors, actuators, and actors). The data reliability is improved by four algorithms, ChooseMedian, ChooseMost, ChooseNearest, and Trust-based Enhancement. Report attainability is improved via m repeat-sending and n multiple-reporting algorithms. Device reliability is guaranteed by device-indistinguishability, which comprises data-indistinguishability and behavior-indistinguishability. The security requirements are formally defined, and the security analysis proves the soundness and completeness of the scheme. Reliability and security are the foremost importance in wireless M2M systems. A simple, target distinguishing attack can result in M2M’s failure. This paper presents a RelIable and SEcure scheme, RISE, which is a package of policies that guarantee the reliability of data (including sensor reports and actuator instructions) and devices (including sensors, actuators, and actors). The data reliability is improved by four algorithms, ChooseMedian, ChooseMost, ChooseNearest, and Trust-based Enhancement. Report attainability is improved via m repeat-sending and n multiple-reporting algorithms. Device reliability is guaranteed by device-indistinguishability, which provides data-indistinguishability and behavior-indistinguishability. The security requirements are formally defined, and the security analysis proves the soundness and completeness of the scheme.