Worse yet, the signature is signed with the same key as is used to sign code, so that once it is broken offline it can be used to send a software update to the SIM. He claims that in ~25% of the cases, the SIM will respond with a signed error message to an invalid attempt to update its code, and that for about 50% of the SIMs on the market, the signature will be encrypted with the very old and crackable Digital Encryption Standard (DES). The crux of his attack is based on the Over-The-Air (OTA) software updates for these cards, which are typically sent via 'secure' binary SMS directly to the SIM. Karsten Nohl had a nice presentation at Blackhat 2013 ( ) claiming that many SIM cards are rootable. I am interested in the technical aspects of the question (there are legal as well, when it comes to a policy there is also the possibility of fraud with the help of a carrier operator who would generate a PUK) *) 'practically possible' means doing it quickly enough to use the SIM before it is blocked (say, an hour) is it practically possible* to crack the PUK code? This one is longer but since it can be recovered by the carrier it means that a SIM ID can be used to generate such a code.

is it practically possible* to crack the PIN code, either directly or by cloning the SIM and testing the 10,000 possible codes?.

What is the reality of this assumption? One of the uses of a stolen mobile phone is to robot-call specific numbers and drain the user account: The theory is that three failed attempts to input the right PIN switches the SIM card into PUK mode, and 10 failed attempts to input the PUK make the card unusable. When deploying a mobile phone best practices policy, one of the points which were raised was the requirement for the user to protect his SIM card with a PIN.

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