Personal unblocking code

A Personal Unblocking Key (PUK ) is an electronic key used to unlock a smart card after a PIN has been entered incorrectly several times. Examples of such chip cards, SIM cards or ID cards with the German eID function.

SIM card

When a SIM card is PUK for unlocking if the Personal Identification Number (PIN) several times, usually three times, was entered incorrectly. The PUK code is not stored in the mobile phone, but linked to the SIM card and can be ascertained from the manufacturer. The PUK has usually eight digits.

The PUK may not be as often entered incorrectly. After eight to ten failed attempts, the SIM card will be permanently blocked. Then a new SIM card must be requested by the network operator. However, this is associated with costs and waiting time.

During the PUK is used to unlock the PIN, PIN2 PUK2 unblocking the serves.

Identity card in Germany

If the eID function used in the new German ID card, it also comes here at three incorrect entries the PIN to a lock that can be canceled with the PUK. The PUK is sent along with the PIN of the Federal Printing in a special letter and can be used up to ten times.