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Home > General > Stolen L322's - Key Protection |
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TheWojtek Member Since: 08 May 2015 Location: PoznaĆ, Poland Posts: 737 |
You put way too much trust in Thatcham. They do not follow the development of hardware and software fast enough to revoke certifications or change the test procedures. The numbers are not random, but pseudorandom. It's a massive difference, and it comes down to a significant certainty of the next sequence that will be expected by the car from the remote. By analyzing the challenge-response handshake between the particular car and the remote, a thief (or rather the software he runs on a laptop, in most cases it happens remotely as to limit the hardware carried during a break-in) is able to reconstruct the algorithm used to generate the "random" numbers. The car is able to receive thousands of challenge signals a second and sort them out to find one that can be responded to. This is because it has to unlock the door in a busy environment of a car park with tens of signals being transmitted simultaneously to unlock and lock various vehicles. I don't know the details exactly, but the remote transmits an unique key identifier (static, does not change), a random sequence (the actual challenge sent to the car that knows exactly which random number to expect) and some additional information (like long/short keypress, the actual button pressed etc, static, because they do not change). This fits nicely into a 24-bit number with over 16M combinations. Perhaps it's a 32-bit transmission? Maybe it's obfuscated with additional encryption? I'm not sure, since this calls for some processing power within the remote itself, so it would be power-hungry. But maybe there is some. Most of the consumer-level encryption can be broken within hours anyway, with a 32-bit transmission we're talking about something as complicated as a four-letter Windows password, my ancient 8-core Mac decrypts such password in less than a minute, brute-force. Never mind, since once you know the actual method of the pseudorandom code, you limit your options to mere hundreds of thousands of attempts. You just burst the bytes on the 432 MHz frequency at a rate of 1000 challenges per second and within single minutes the car is unlocked. It's like wifi security - when wifi was invented, a WEP password was considered too complicated to hijack and decode. Within 5 years the technology has progressed to a level that allows breaking a WEP password instantly. Same with car security, it has to be a foolproof and extremely durable, well-established technology, which makes it outdated at the very time it's being first implemented. Also see: https://www.breakerlink.com/blog/security/...rity-stop/ Regards etc., Wojtek --- WAS: 2006 RRS Supercharged IS: 2010 RRS TDV8 HSE |
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Fri Jun 09 2017 10:27am |
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Andy d Member Since: 07 Oct 2014 Location: Sheffield Posts: 43 |
i had to have a cat 5 tracker for insurance i opted for the smart track |
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Fri Jun 09 2017 4:50pm |
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Gerd1986 Member Since: 07 Oct 2015 Location: London Posts: 303 |
Just to update on this.
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Tue Jun 27 2017 12:48pm |
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