- Personal Unblocking Code
: "For other meanings of the acronym PUC, see the disambiguation page
PUC ."A Personal Unblocking Code (PUC) or Personal Unblocking Key (PUK) is used in
GSM mobile phone s and somesmartcards to unblock a blocked card.Most mobile telephones offer the feature of
personal identification number (PIN) protection. After switching on the phone, if the PIN security function is not switched off, the user is requested to enter a 4-8 digit PIN enabling the phone's non-emergency calling functions. If the wrong PIN is typed in more than three times, either theSIM card , the device or both become locked. They can be reverted to their original unlocked state by entering a PUC, provided by the service operator through verification. If the wrong PUC is entered ten times in a row, the device will become permanently blocked and unrecoverable, requiring a new SIM card. Cellular phone users are therefore advised by most providers to keep their PUC written down in a safe place separate from the device.References
* Antonio Savoldi & Paolo Gubian, "SIM and USIM filesystem: a forensics perspective" "Proceedings of the 2007 ACM symposium on Applied computing" (2007): 183. "CHV1: the command is executable on the file only if one among Card Holder Verification 1 code or Unblock Card Holder Verification 1 (called also PUK1, that is the Personal Unblocking Code 1) code has been successfully provided;" Similar remarks for CHV2.
External links
*Official 3GPP ETSI Specification of the Subscriber Identity Module - Mobile Equipment (SIM-ME) Interface: [http://www.3gpp.org/ftp/Specs/html-info/1111.htm]
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