Reverse Engineering the GMR-2 Standard: Two Chinese researchers have developed a method for decrypting satellite telephone communications that works almost instantly and provides access to secure third-party conversations in real time.
Their method appears to present no problems against GMR-2, the latest version of the GEO-Mobile Radio Interface used to support satellite telephone communications with airborne satellites.
GMR-2 encrypts all data sent from the user's phone to the satellite via a 64-bit key.
The new attack on GMR-2 is much faster than the previous one
In research papers published earlier in 2012 and 2013, a team of five researchers from Ruhr University in Bochum, Germany, developed an attack against the encryption of satellite phones that use the GMR-2 standard for communications security.
The German team's research described the first attack on the GMR-2 standard, but it was complex and difficult to execute in everyday life as it required time to calculate all the mathematical equations required to recover the encryption key used to secure satellite phone communications.
In a paper (PDF) published last week, two Chinese researchers from the National University of Defense Technology in Changsha, China, describe a new attack against GMR-2 encryption that can be carried out in fractions of a second, allowing an attacker to instantly obtain the encryption key.
Reverse Engineering in GMR-2 Encryption
The Chinese researchers say their method is different from the one developed by the German team. Instead of trying to perform “plaintext attacks” on the encryption key through “read-collision” and “guess-and-determine” methods, the Chinese team reverse-engineered the entire process a phone goes through to choose an encryption key.
This allowed the researchers to design an accurate system for determining the encryption key a satellite phone uses to encrypt its data by examining the already encrypted data sent by the phone.
Although for now we are talking about an academic and scientific success, this particular research could have devastating results, given that this new attack could be used to monitor satellite telephone communications.
Satellite phones are a vital piece of equipment, often used in wars, by secret agents, activists, dissidents and many others.
