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New Attack Can Now Decrypt Satellite Phone Calls in 'Real Time' (zdnet.com)
Chinese researchers have discovered a way to rapidly decrypt satellite phone communications -- within a fraction of a second in some cases. From a report on ZDNet: The paper, published this week, expands on previous research by German academics in 2012 by rapidly speeding up the attack and showing that the encryption used in popular Inmarsat satellite phones can be cracked in "real time." Satellite phones are used by those in desolate environments, including high altitudes and at sea, where traditional cell service isn't available. Modern satellite phones encrypt voice traffic to prevent eavesdropping. It's that modern GMR-2 algorithm that was the focus of the research, given that it's used in most satellite phones today. The researchers tried "to reverse the encryption procedure to deduce the encryption-key from the output keystream directly," rather than using the German researchers' method of recovering an encryption key using a known-plaintext attack. Using their proposed inversion attack thousands of time on a 3.3GHz satellite stream, the researchers were able to reduce the search space for the 64-bit encryption key, effectively making the decryption key easier to find. The end result was that encrypted data could be cracked in a fraction of a second.
New firmware on both phones and satellites? Might be a problem.
If this is what Chinese academics are publishing now, I wonder how long this has been possible in less-publicized circles.
Everybody knows that certain governments buy up crypto expertise as soon as the ink on the PhD dries. Or sooner, in some cases.
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According to the latest ruleset, this post should be modded as Vorpal Flamebait +5.
OK, so now all five satellite phone users will be inconvenienced.
The big geosync ones are just active retransmitters of radio spectrum. Even the switched ones have no
reason to decrypt the audio. A phone update for a more agile key might do the trick.
Why are they still using 64 bit encryption in this day and age, especially for satellite communications which can be eavesdropped upon pretty easily, and two why are any users of this technology not ensuring whatever they are sending via the phone is encrypted/ciphered/otherwise obfuscated before it ever reaches the phone?
P.S. Guess we know how they found Osama and probably El Chapo as well.
Some variant of Diffie-Helman key exchange would probably do quite nicely...
Sorry, no. The attack described is on the GMR-2 stream cipher itself, not the key exchange. Because of a weakness in the key schedule of the cipher, and the underlying structure of the encrypted data frame related to the key schedule, they can actually recover the key directly from they encrypted data frame ignoring the session key exchange entirely.
The fact that they are using some crappy secret stream cipher to sat-phones is a testament to how little research has gone into good stream ciphers (vs creating block ciphers like AES). Although we also shouldn't be too smug about AES either. In a similar vein, a weakness in AES block cipher key schedule was not detected until many years later made AES-256 less secure than its 2^256 key-space would indicate (in fact because of this weakness, AES-256 may be even less secure than AES-192). And AES is/was a heavily researched block cipher, not a "secret" satellite phone cipher.
Satellite phones are no more secure than cellphones?
Sure, that's disappointing, but the reason people use satphones isn't that they're more secure. It's that they can be used in remote places.
I'm WAY more concerned that standard cell phone networks use a known weak cypher to encrypt calls, since that affects 99.5% of people. I just can't get outraged that the other 0.5% are now similarly affected.