User reports GNUK 1.2.14 losing his keys

[NIIBE Yutaka]

Hello, again,

Looking at the support page of yours, I'm afraid you suggested wrong
direction (if you want to identify the real cause of the problem).

Let me explain a few things.

For use of GnuPG with Gnuk Token (or OpenPGPcard), I believe that the
best way is using scdaemon with the internal CCID driver.  When
something goes wrong in USB communication, it can detect problem
soonish.

To detect device event reliably, Gnuk specifically uses the USB endpoint
2 for its interrupt endpoint, although it is a token with fixed card.
(Such an endpoint is used to notify host for card events of
insertion/removal.)  It works well with the internal CCID driver; when
USB connection going wrong, scdaemon is notified.

Scdaemon supports PC/SC, because there are situations where it is
needed; Like on system with Windows/macOS, or environment where use of
other card is required.  PC/SC itself is a subsystem, a bit complicated.
It has/does its own internal error handling.  So, scdaemon cannot get
fine-grained information in some situations.  I'd recomend use of the
internal CCID driver, especially when we need to identify the device
problem.

And, suggesting shared use of a USB device by multiple applications in a
violent way (no coordination among multiple applications) may just
compilicate things.  If it is common practice among your users to try
such a thing, I have no wonder observing problem of 0 0 0 and 0 0 0 and
0 and triple [none].  For use by other applications, we keep suggesting
a solid method of:

	gpgconf --kill scdaemon

instead.

Well, for me, it looks like the device itself works fine and it seems
that it's other part(s) of user's system which caused the problem.
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