Comment Re:switching the number won't work (Score 1) 561
ok let me make a few corrections....
You cannot clone a GSM sim - Not Correct
A GSM phone has a unique IMEI number - correct
Each GSM phone has a unique sim card with a unique sim number, This sim number is attached on a central computer to your account - Mostly correct
Although the sim card does not contain your number is is mainly for informative, and not for operational purposes. - Not correct
The IMEI number is used to identify the user - Not correct
you cannot use a phone in an airplane as it will sign onto every cell site it sees breaking the network - Not correct.
First of all the sim number printed on the sim is just the serial number of the peice of plastic. its an inventory number. Sort of useful but in reality not very.
The Sim is actualy an extremely sophisticated computer in its own right. it has ROM, RAM and EEPROM. It has its own operating system, and holds some applications, the security algorithms A3 and A8, The Keys to the kingdom - KI, and the subscriber identity IMSI.
The subscriber is identified by IMSI, MSISDN, TMSI and MSRN
Only the handset is identified by IMEI
Two ways to clone a GSM sim:
1) break it over the air:
Adi Shamir, Alex Biryukov and David Wagner wrote a paper on Cryptanalysis of A5/1 which shows you one way.
http://cryptome.org/a51-bsw.htm
unfortunately it is flawed. Ill give you a prize if you know how. .....However if you know how it is flawed, you can easily work out how to make the attack viable...
2)Brute force the SIM. If your sim is protected by comp128 and it hasnt been programmed to suicide after a finite number of brute force attempts then using a "phoenix" type smart card reader and some readily available software you can brute force the sim after a couple of hours. Once succesfull you can take a copy of the IMSI and KI to store as you see fit.
One amusing educational exercise when you do have a copy of your KI and IMSI is to write a copy of the application "sim menu" to a programmable card and add your sims identity to it. Then repeat this exercise with a few additional sims until you have a home made "multisim". When you start the phone you will get a menu asking you which simcard identity you wish to use. Which ever one you activate is the one that receives and sends calls.
No its not possible to have more than one sim identity active at the same time.
This is not possible with the sims for pretty muchg all the major operators in the western hemisphere. For the simple reason that the sim has been programmed to suicide after a certain number of attempts to access it. You need more than this number of guesses (or lots of luck) to crack the sim.
So anyway, the chances of you being cloned are slim. its possible but not likely.
Its far more likely the network operator made a mistake, or that you ahve roaming charges that are only just being applied to your account. When roaming, operators tend to get inconsistent data and sometimes this can take a month or more to appear on your bill.
Of course theres the other possibility that your partner made the calls.
Last but not least thye myth that using a GSM phone on an aiplane will crash a network becuase it tries to sign onto too many cells. This is exactly that. A myth.
A GSM handset will lock onto the single strongest signal. If a stronger one comes along then it will hop onto that one.
anyway its likely we will have mobile coverage on planes by the end of this year or early next.
http://www.theregister.co.uk/2005/06/16/planes_cel lphones_boeing/
just like in the case of hospitals, the main reason for banning cell phones was paranoia (though they did interfere with some types of fire system).
cj
You cannot clone a GSM sim - Not Correct
A GSM phone has a unique IMEI number - correct
Each GSM phone has a unique sim card with a unique sim number, This sim number is attached on a central computer to your account - Mostly correct
Although the sim card does not contain your number is is mainly for informative, and not for operational purposes. - Not correct
The IMEI number is used to identify the user - Not correct
you cannot use a phone in an airplane as it will sign onto every cell site it sees breaking the network - Not correct.
First of all the sim number printed on the sim is just the serial number of the peice of plastic. its an inventory number. Sort of useful but in reality not very.
The Sim is actualy an extremely sophisticated computer in its own right. it has ROM, RAM and EEPROM. It has its own operating system, and holds some applications, the security algorithms A3 and A8, The Keys to the kingdom - KI, and the subscriber identity IMSI.
The subscriber is identified by IMSI, MSISDN, TMSI and MSRN
Only the handset is identified by IMEI
Two ways to clone a GSM sim:
1) break it over the air:
Adi Shamir, Alex Biryukov and David Wagner wrote a paper on Cryptanalysis of A5/1 which shows you one way.
http://cryptome.org/a51-bsw.htm
unfortunately it is flawed. Ill give you a prize if you know how.
2)Brute force the SIM. If your sim is protected by comp128 and it hasnt been programmed to suicide after a finite number of brute force attempts then using a "phoenix" type smart card reader and some readily available software you can brute force the sim after a couple of hours. Once succesfull you can take a copy of the IMSI and KI to store as you see fit.
One amusing educational exercise when you do have a copy of your KI and IMSI is to write a copy of the application "sim menu" to a programmable card and add your sims identity to it. Then repeat this exercise with a few additional sims until you have a home made "multisim". When you start the phone you will get a menu asking you which simcard identity you wish to use. Which ever one you activate is the one that receives and sends calls.
No its not possible to have more than one sim identity active at the same time.
This is not possible with the sims for pretty muchg all the major operators in the western hemisphere. For the simple reason that the sim has been programmed to suicide after a certain number of attempts to access it. You need more than this number of guesses (or lots of luck) to crack the sim.
So anyway, the chances of you being cloned are slim. its possible but not likely.
Its far more likely the network operator made a mistake, or that you ahve roaming charges that are only just being applied to your account. When roaming, operators tend to get inconsistent data and sometimes this can take a month or more to appear on your bill.
Of course theres the other possibility that your partner made the calls.
Last but not least thye myth that using a GSM phone on an aiplane will crash a network becuase it tries to sign onto too many cells. This is exactly that. A myth.
A GSM handset will lock onto the single strongest signal. If a stronger one comes along then it will hop onto that one.
anyway its likely we will have mobile coverage on planes by the end of this year or early next.
http://www.theregister.co.uk/2005/06/16/planes_ce
just like in the case of hospitals, the main reason for banning cell phones was paranoia (though they did interfere with some types of fire system).
cj
