Cryptographic security for the new trans-European trunked radio (TETRA) standard

TETRA is currently being standardised by the European Telecommunications Standards Institute´s (ETSI) Sub Technical Committee 6 on Radio Equipment and Systems (RES6). It allows speech and data communications within a closed user group, such as a vehicle fleet or emergency services. Unlike most presently available trunked radio systems, TETRA provides digital transmission, which permits among other things the integration of high quality cryptographic security mechanisms. Cryptography already played an important role in DECT and GSM, two digital radio systems that have been standardised by ETSI before. The results of these projects were, of course, used as a starting point for the work in TETRA. There are, however, some important differences in requirements, which have an impact on the design of the security mechanisms for TETRA. In particular, since public safety forces are expected to form one of the most important user groups for TETRA, a higher level of security had to be considered in the development of the TETRA standard. The article describes the activities and results to date of working group 6 (WG6) of RES6 on TETRA security