Dual SIM?

David Pottage david at electric-spoon.com
Thu Jun 12 17:20:47 CEST 2008

On Thu, June 12, 2008 3:21 pm, Bumbl wrote:

> would it, in theory, be possible to emulate a 2nd sim-card which was
> inserted and saved on the flash memory before and switch between it
> and the inserted one?

In theory this is possible if you can extract the 128 bit crypto key
inside the SIM which is used to authenticate the SIM card to the
network. Because of weaknesses in the crypto algorithms used by GSM it
is possible to extract that secret from a SIM card using about 60 000
chosen challenges, which can be done in about 12 hours. (assuming the
SIM card does not have a retry counter)

If you manage to do all of that, then yes you could have as software
copy of one or more SIM cards and switch between them, thought the GSM
module will only ever be able to use one at a time.

You should also bear in mind, that some people may consider cloning SIM
cards to be illegal computer hacking or circumvention technology,
especially networks who might object to you using cloned SIM cards to
do least cost routing.

See http://www.cl.cam.ac.uk/~rja14/Papers/SE-17.pdf

David Pottage

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