Thank you very much for your answer, it helps a lot!
________________________________ From: Sascha Krissler <[email protected]> To: [email protected] Sent: Fri, May 14, 2010 1:56:02 AM Subject: Re: [A51] rainbow table The size of an LAPDm frame is always 23 bytes, but most messages are shorter. A good candidate is the CIPHER MODE ENABLED message which is the first encrypted message sent in a connection and only uses 3 bytes. So 20 unused bytes are padded with a constant (0x2b). Another source of known plaintext are messages with predictable content, for example SYSTEM INFORMATION messages, which are the same for all subscribers of a cell and are periodically sent to each connected MS. Among those known bits of information are frequency allocation of neighbouring cells, "location area identification" or "cell identity". In theory from analysis of the voice codec and the forward error correction there may be sources of known plaintext bits found in the bursts transmitting voice data. AFAIK nobody from the project looked into this by now. --------------------- Von: MIHAITA ADELA <[email protected]> Gesendet: 13.05.2010 19:08:29 An: [email protected] Betreff: [A51] rainbow table Hello, I'm interested to learn more about the project you're working on and I would kindly ask you to help me with an answer to a simple question. As far as I understood, the rainbow tables provide, for 64 bits known of keystream, the initial internal state that generated those bits. Once you have the initial internal state, you can find the secret key used. My question is how do you have access to few samples of 64 bits of keystream, how do you get to find them out? Is it because of that padding with known plaintext? but then, I don't get it with that known plaintext, who add is there? I tried to follow the explanations given in the "GSM Basic" section but it's not clear for me. Thank you very much, ___________________________________________________________ NEU: WEB.DE DSL für 19,99 EUR/mtl. und ohne Mindest-Laufzeit! http://produkte.web.de/go/02/
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