There are two irreversible trends in law enforcement communications today, which are putting contradictory pressures on the need for communications security. The first is the increasing sophistication of the adversary, and the adversary's ability to intercept and monitor wireless communications. The second is law enforcement's increasing reliance on commercial solutions to wireless communications. The providers of commercial solutions do not provide high grades of security being limited by financial feasibility and technical expertise. Exacerbating this situation is the fact that there are only two current alternatives to law enforcement communications security; the traditional DES encryption and the U.S. government's Type 1 high- grade encryption. The former is no longer sufficiently robust against sophisticated adversaries, and the latter is encumbered by restrictions of use. The need is for an encryption technology that combines the advantages of the government's high grade security, with the cost efficiency of a reprogrammable, commercially produced, encryption module. The Harris Secure Products group has research and development underway which will enable such a next generation encryption module, project named Sierra. The Sierra objective is a programmable device, capable of providing Type 1 (U.S. government), Type 3, and Type 4, or a combination thereof. The device also facilitates the necessary voice processing algorithms to support legacy and future equipment. Unlike current Type 1 devices, a module based on Sierra would not be subject to controlled handling procedures when not programmed for Type 1 applications. This allows for law enforcement agencies to downgrade and upgrade their communications equipment appropriate to the adversary, and according to interoperability requirements. This paper will describe the various technologies and techniques being used in the development of the Sierra.