Using OpenPGPcard through PC/SC service and with reader of Short APDU level exchange only

[NIIBE Yutaka]

Hello,

I don't have the smartcard reader of "Short APDU level exchange only".
If someone could test STABLE-BRANCH-2-0 with such reader(s), it is
greatly appreciated.

I'm looking the bug report:

	https://bugs.g10code.com/gnupg/issue1405

I guess that

	issue1105
	issue1113
	issue1114

would be by the same cause.

I think that this bug could be solved, if we improve app-openpgp.c.

During the development of Gnuk, I realized that smartcard related
communication protocol is basically *broken*.  Right Engineer tries to
implement thinking the layer model and the abstraction, but it is
impossible for smartcard.

In case of OpenPGP card, the application needs to know if the reader
supports extended APDU level exchange or not (in case of PC/SC
service).

Note that Gnuk 1.0.x is "Short APDU level exchange only", and it works
well because its historical bytes specify no extended Lc and Le.
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