Attacks on the DECT Authentication Mechanisms

Digital Enhanced Cordless Telecommunications (DECT) is a standard for connecting cordless telephones to a fixed telecommunications network over a short range. The cryptographic algorithms used in DECT are not publicly available. In this paper we reveal one of the two algorithms used by DECT, the DECT Standard Authentication Algorithm (DSAA). We give a very detailed security analysis of the DSAA including some very effective attacks on the building blocks used for DSAA as well as a common implementation error that can practically lead to a total break of DECT security. We also present a low cost attack on the DECT protocol, which allows an attacker to impersonate a base station and therefore listen to and reroute all phone calls made by a handset.