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willem itsme at xs4all.nlOn 2010-04-13 21:07:08, Harald Welte wrote: > Hi Jake (and others), > > On Tue, Apr 13, 2010 at 10:09:52AM -0700, Jacob Appelbaum wrote: > >>> I've written an introductory text on GSM mobile phone architecture, >>> and before officially posting/announcing it, I thought I'd invite >>> the members of this list to do some review and give feedback! >>> >> Do you have the latex available? It's hard to edit and send a diff of a >> pdf... >> did you omit qualcomm in your list of baseband manufacturers intentionaly? because it produces mostly cdma and 3g chipsets, and not gsm? i have several additions to your document: == in the list in subsection{MCU peripherals} \item Audio routing, selecting how audio is routed in the phone, between AP, BB, carspeaker,headset, mediaspeaker, phonespeaker and microphone == addition to \subsection{The Digital Baseband (DBB)} The baseband MCU usually runs a realtime operating system(RTOS), like nucleus, vxworks, or l4k. == a subsection in section{Miscellaneous Topics} \subsection{Security features} There are several things that need protection against tampering in a gsm phone, the Ki ( the secret key which identifies the subscriber to the network ), the IMEI ( the hardware id of the phone ), and various restrictions set by your cellular provider (commonly known as 'the simlock'). The Ki is stored in the SIM, and is never handled by the baseband software directly, it cannot be read from the SIM. The IMEI on the other hand is just an arbitrary string stored in flash, usually obfuscated in some way, to make it more difficult to change. But there is no special hardware ( like a SIM ) involved in protecting it. willem