Abstract: Data transmission to an aircraft is secured by encrypting the data between a remote data source and the aircraft. The encryption is initiated when a random number is coupled to the remote location where it is encoded with the data in accordance with a preselected encryption sequence. The encoded data, after transmission to the aircraft, is decoded in the same sequence so that the original data may be retrieved.

Abstract: An inductive coupling permits bi-directional data and power to be transferred through the skin of an aircraft thereby avoiding pin connectors. The coupling comprises a sending unit which is detachably mounted to the skin exterior, and the pick-up unit is located on the interior skin surface in alignment with the sending unit.

Abstract: Aircraft often include a central memory which distributes data to a number of communication, navigational and other utilization devices. In order to achieve a high degree of security for data transmission from the memory to the utilization devices, data subsets are distributed to the utilization devices in parallel so that any radiation generated from the parallel branches results in superposition of individual data signals. In effect, a jumbled resultant signal is produced which is difficult or near impossible for unfriendly surveillance equipment to decipher.

Abstract: Data protocol and format parameters are encoded by a modified connector located between a data source and a receiving memory. The modification includes the opening or shorting of pin connectors in a unique pattern corresponding to particular protocol and format parameters of a data utilization device.