How to enable ack button functionality on FST-01sz

[NIIBE Yutaka]

Mark Debian wrote:
> Can someone tell me how to enable the ack button functionality using
> FST-01sz?  When I configure latest gnuk, before compiling, the output
> of the configure command says:"Acknowledge button is supported"

Currently, it is only supported in GnuPG in master (to be 2.3).
With "--card-edit" option, we have "uif" sub-command (User Interaction
Flag) to enable/disable the functionality.  When enabled, a user
has to acknowledge the operation (sign/decrypt/auth) by the device.

Personally, I don't use it.  For SSH key, I use the feature of gpg-agent
which asks confirmation (by pop-up window on desktop).
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