Voice end-to-end encrypted for TETRA radiocommunication system

The standard TETRA (Terrestrial Trunked Radio) system addresses a number of security issues, one being the cryptographic protection of signaling data and user data on the highly exposed air interface. However, user data travels unencrypted within the network infrastructure. This precludes the use of TETRA systems by those users who regard their transmissions as particularly sensitive, and whose Security Policy requires all such data to be appropriately encrypted whilst in transit between the end terminals in any system. End-to-end encryption addresses these concerns by encrypting data within the transmitting terminal, and only decrypting it within the receiving terminal. The plain data is never exposed within the infrastructure; in fact the infrastructure contains no mechanism to recover it should it wish to do so.