Threats and potential countermeasures for PMR systems

Abstract

The objective of the paper is to identify the threats to PMR systems and consider how different approaches to the implementation of cryptography and key management counter these threats when seen from the point of view of different interest groups. The paper therefore provides an overview of the threats to PMR (Professional Mobile Radio) systems, taking into account the different potential attacker groups and the difference in the perception of the threats from the point of view of users and system operators. The paper then goes on to look at the different options for the use of cryptography for authentication (user to network, network to user), confidentiality (air interface, or end to end) and the methods used for protection against traffic analysis. The various options are then be assessed against the threats identified earlier, using examples from systems such as GSM, Tetrapol and newer interoperability standards such as FNBDT (Future Narrow Band Digital Terminal). The key management options for supporting point to point and group communications are addressed. Identifying some of the problems with the different approaches that may be taken to counter the perceived threats. This includes the use of PKC (Public Key Cryptography) techniques for key management and distribution, symmetric schemes and examples of some of the problems of combined authentication and confidentiality interdependencies. (6 pages)