Satphone Encryption Cracked

In places where cellular communications is not possible, satellite phones have been used. These include sites of war, third-world countries, and out atop the ocean blue. Now a team of German researchers have found that encryption used in the popular GMR-1 and GMR-2 phones is mathematically weak.

Working at the Ruhr University Bochum's (RUB) Horst Görtz Institute for IT-security, Benedikt Driessen, Ralf Hund, Carsten Willems, Christof Paar, and Thorsten Holz were able to reverse engineer the encryption algorithms. They noted that the GMR-1 algorithm is very similar to the GSM A5/2 algorithm, which is known to be broken. "A major finding of our work is that the stream ciphers of the two existing satellite
phone systems are considerably weaker than what is state-of-the-art in symmetric cryptography."

The good news is that unlike breaking GSM A5/2, in which Karstan Nohl showed he could later listen to intercepted cellular conversations at Black Hat 2010 and DefCon 18, the RUB team could not hear the satellite communications from one of the GMR-1 satphones they tested. But that researcher is ongoing.

Satphones are used by approximately 100,000 subscribers worldwide, including both consumer and government uses.

"Our results show that the use of satellite phones harbors dangers and the current encryption algorithms are not sufficient," concluded one of the authors. Unfortunately, there is no replacement standard available at this time.

The full details can be found here.