Privacy and authentication on a portable communications system

The authors discuss technical options to achieve adequate privacy and fraud control for portable communication systems. As the goal is to provide privacy at least comparable to that provided by wireline, the authors concentrate on the privacy of conversations on the radio link only. A high-level description of the portable communications system is presented, which provides a basis for further discussion. Message encryption is considered, the process by which a cipher function is applied to the portable communications systems data streams in order to deter eavesdroppers. Some background on public-key cryptography and some information regarding implementation of public-key techniques in low-power portable units are given. Key agreement and authentication protocols are outlined