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Sébastien Lorquet squalyl at gmail.comOn Tue, Mar 16, 2010 at 12:07 PM, Dieter Spaar <spaar at mirider.augusta.de>wrote: > Hello Sebastien, > > On Tue, 16 Mar 2010 10:04:07 +0100, "=?UTF-8?Q?S=C3=A9bastien_Lorquet?=" < > squalyl at gmail.com> wrote: > > > > I know that smart card EEPROMS are rated for 100k writes, but I would not > > rely on that. In fact, this depends on how often is the EF.Kc file > written, > > which was my original question. Every 30 seconds or every day? Every day > is > > of course OK. > > It is only written if an AUTHENTICATION REQUEST from the network is > performed. This usually happens when the phone is turned on and > does a location update. The network can also perform an AUTHENTICATION > REQUEST when doing a call or similar things, however usually this is > not done every time and the previous Kc stored on the SIM is reused > as Sylvain explained it. For OpenBSC and OpenBTS the default is that > there is no AUTHENTICATION REQUEST at all, so no Kc is written (I am > not 100% sure if this is true for OpenBTS, but I guess so). > > > Additionally, how often are these other files written (LOCI, BCCH) ? > > They are written when a location update is done or the cell changes. > However it depends on the phone if the data is really written to the > SIM every time, sometimes the phone caches those data and writes them > to the SIM only when the phone is turned off. For OpenBSC and OpenBTS > writing should not happen that often because there is usually only one > cell with fixed parameters. And I guess you will probably not actually > write to the EEPROM if the same data is already stored (or a least > the Card OS should do it this way). > OK, I will neglect this part for the moment and implement them as regular files. If it happens that the update rate is really a danger for the card eeprom, I'll implement a log structured file type. > SmartCardFocus has a ID0 cutting service, that can turn any card into a > SIM > sized module: > http://www.smartcardfocus.com/shop/ilp/id~82/p/index.shtml > This is the best option I know so far. > Thanks, I did not know that. It would be interesting to know what tool they use and if it is available for a reasonable price. Seems to be 1.20 EUR per card. Two options: either they may have a small punching tool, and do that by themselves, or they may have a subcontractor with a big laser cutter or a CNC or something else... There were impressive machines at the Cartes Salon, I would not be surprised if they had a supplier with a monster to do that. Sebastien -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/baseband-devel/attachments/20100316/87282187/attachment.htm>