Scdaemon CHECKPIN - Using the GNU Privacy Guard
Description: Using the GNU Privacy Guard

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#### 5.6.13 Perform a VERIFY operation.

           CHECKPIN idstr

Perform a VERIFY operation without doing anything else. This may be used to initialize a the PIN cache earlier to long lasting operations. Its use is highly application dependent:

OpenPGP
  Perform a simple verify operation for CHV1 and CHV2, so that further operations won't ask for CHV2 and it is possible to do a cheap check on the PIN: If there is something wrong with the PIN entry system, only the regular CHV will get blocked and not the dangerous CHV3. idstr is the usual card's serial number in hex notation; an optional fingerprint part will get ignored.

  There is however a special mode if idstr is suffixed with the literal string `[CHV3]`: In this case the Admin PIN is checked if and only if the retry counter is still at 3.