Manually changing smartcard state

[Johannes Zarl]

> Is it possible to change the smartcard state after PIN is entered, so it
> would be back in the same state as it was when first inserted into the
> reader (and would require the PIN to be entered again also for
> decryption)? So without removing and re-inserting the card, possibly
> using some APDU instructions.

You can tell gpg-agent to lock the card using the following command[1]:

gpg-connect-agent 'SCD RESET' /bye

[1] http://lists.gnupg.org/pipermail/gnupg-users/2011-January/040478.html