Published in News this week, expands on earlier research by German academics in 2012 by quickly speeding up the attack and determining that the encryption used in popular Inmarsat satellite phones can be tracked in “real time.”
Satellite phones are adopted by those in desolate surroundings, including high elevations and at sea, where regular cell service isn’t available. Modern satellite telephones encrypt voice traffic to prevent eavesdropping. It’s that new GMR-2 algorithm that was the center of the research, given that it’s used in maximum satellite phones today.
The researchers tried “to turn the encryption method to understand the encryption key from the output keystream directly,” rather than practicing the German researchers’ method of recovering an encryption key using an obvious-plaintext attack.
Using their proposed conversion attack thousands of time on a 3.3GHz satellite stream, the researchers were ready to reduce the search space for the 64-bit encryption key, effectively making the decryption key natural to find.
The end outcome was that encrypted data could be solved in a fraction of a second.
“This again shows that there exist serious security flaws in the GMR-2 cipher, and it is important for service providers to upgrade the cryptographic modules of the way in order to provide confidential communication,” said the researchers.
An Inmarsat spokesperson said Thursday that the group “immediately took action to discuss the potential security issue and this was fully discussed” in 2012. “We are entirely confident that the issue… has been completely fixed and that our satellite phones are secure,” the spokesperson said.
Matthew Green, a cryptography professor at Johns Hopkins University, blogged about the German read-collision lowered technique in 2012. “Satellite telephone security matters,” he said at the time. “In many weak rural areas, it’s the primary means of interacting with the outside world. Satphone coverage is also essential in war zones, where signal privacy is of more than academic interest,” he added.
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