Sébastien Lorquet squalyl at
Tue Mar 16 10:26:05 UTC 2010

On Tue, Mar 16, 2010 at 12:07 PM, Dieter Spaar <spaar at>wrote:

> Hello Sebastien,
> On Tue, 16 Mar 2010 10:04:07 +0100, "=?UTF-8?Q?S=C3=A9bastien_Lorquet?=" <
> squalyl at> 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

 > sized module:


 > 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.

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