How secure is OTAR?
Posted: Sun Aug 27, 2006 9:13 pm
I was reading up a bit on how OTAR (Over The Air Rekeying), It looks like each radio is loaded with an encryption key (the KEK, or "Key Encryption Key"), and the new 'voice key' is sent out encrypted with the KEK.
This leads me to two questions:
- If I'm an evil archvillian trying to crack the secure comms, what stops me from just cracking the KEK? If I crack the KEK, I know the key for whatever voice comms you use, so the voice encryption is basically useless. (And if the KEK is astronomically more secure than the voice key, why not just use the KEK to encrypt voice traffic?)
- If the evil archvillian, instead of running his underground lair of supercomputers, just goes and steals someone's radio, doesn't he then know the KEK? And, provided he can figure out a way to keep the stolen radio from being inhibited (perhaps be could ask on Batboard), wouldn't the radio receive all key updates, thus being able to listen to all traffic until the radios were physically reprogrammed with a new KEK?
Do I misunderstand a step? Because it seems to me like the only way to keep OTAR secure is to physically put new KEKs into the radios very often. (But if you're doing that, you might as well skip OTAR and just put new voice keys in?)
This leads me to two questions:
- If I'm an evil archvillian trying to crack the secure comms, what stops me from just cracking the KEK? If I crack the KEK, I know the key for whatever voice comms you use, so the voice encryption is basically useless. (And if the KEK is astronomically more secure than the voice key, why not just use the KEK to encrypt voice traffic?)
- If the evil archvillian, instead of running his underground lair of supercomputers, just goes and steals someone's radio, doesn't he then know the KEK? And, provided he can figure out a way to keep the stolen radio from being inhibited (perhaps be could ask on Batboard), wouldn't the radio receive all key updates, thus being able to listen to all traffic until the radios were physically reprogrammed with a new KEK?
Do I misunderstand a step? Because it seems to me like the only way to keep OTAR secure is to physically put new KEKs into the radios very often. (But if you're doing that, you might as well skip OTAR and just put new voice keys in?)