Conventional cryptographic security mechanisms are essential for securing wireless networks, but they do not directly leverage the unique properties of the wireless domain. The properties of the wireless medium are a powerful source of domain-specific information that can complement and enhance traditional security mechanisms. IAI and its collaborators at BAE Systems are developing RAPOR, the Reciprocity Aware Protocols for Radios. Reciprocity, a property of most wireless propagation media, means that propagation direction does not have any impact on the Channel Impulse Response (CIR). RAPOR will extend the concepts of physical layer security beyond its current state of theoretical and academic research, and enable deployment in real-world wireless systems. This effort will investigate the degree to which the typical wireless channel, as witnessed by real radios, is reciprocal. It will study whether a secret key of sufficient length and entropy can be generated from this reciprocity, and how the secret key establishment using the physical layer withstands the scrutiny of a variety of adversarial models. It will also investigate how the proposed secret key establishment can be integrated in a holistic cross-layer security framework. Practical benchmarks have already been established using theoretical models from information theory, propagation theory, and empirical results from laboratory experiments. The feasibility and success of physical layer key establishment will be evaluated. Algorithms will be developed that can generate secret keys using the physical layer. Finally, a realistic prototype system will be implemented and tested in the laboratory. RAPOR will lead to a suite of security solutions that operate in a cross-layer manner and greatly enhance the secure operation of tactical and commercial wireless systems.