Message: 1 Date: Thu, 8 Jul 2010 19:40:13 +0200 From: Sylvain Munaut <[email protected]> Subject: Re: [A51] Trying to decipher burst "off the air" To: a51 <[email protected]> Message-ID: <[email protected]> Content-Type: text/plain; charset=UTF-8
Hi again, A little follow up to my earlier problems, for the archives. What I wanted to do is simply decipher a burst for which Ihad the key. Sounds simple right ? Well turns out there were two complications (for me at least :) * The key byte order you must feed the algorithm is not the same as the one stored in the SIM or returned by GSM algo of the SIM. * The "22 bits frame number" you must feed is not very detailled in a lot of 'quick a5 intros'. Turns out it is ((T1 << 11) | (T3 << 5) | T2) Once I fixed that, it all worked out fine :) Cheers, Sylvain ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Hi! I try to feed A *pedagogical implementation* of A5/1 with Kc and 22 bits frame number byte by byte in the way you give it, but I didn't get the same stream like you? Can you please explain order of bytes(bits) for Kc and 22 bits frame number you gave? Thank you very much!
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