Satellite telephony has also been considered to be much safer than traditional cellular service. However, researchers at the Horst Goertz Institute for IT-Security (HGI) at the Ruhr University Bochum (RUB) in Germany claim to have cracked the A5-GMR-1 and A5-GMR-2 encryption algorithms of the European Telecommunications Standards Institute (ETSI), which are used globally by satellite telephones.
The scientists said that they found the encryption key necessary to intercept conversations in under an hour using open-source software and "simple equipment". The approach consisted of a firmware update for the two test phones to reconstruct the encryption process. An analysis revealed that the GMR-1 is rather similar to GSM encryption.
"Since the GSM cipher had already been cracked, we were able to adopt the method and use it for our attack", said Benedikt Driessen, of the Chair for Embedded Security at RUB. His colleague Carsten Willems noted that the researchers were "surprised by the total lack of protection measures."
Given the fact that satellite phones are an essential communication tool of military personnel in war zones, the discovery could lead to drastic policy changes.