scd: PC/SC pinpad input improvement

[NIIBE Yutaka]

On 2013-08-27 at 09:29 +0200, Werner Koch wrote:
> Something different: During a presentation I did last week, I realized
> that the default timeout of the SPR532 is a bit short.  As of now the
> pop up window has a pretty short message but we may change this and the
> user will need more time to read that message - by then she may have
> already run into a timeout.  Shall we add a configuration option to
> change the timeout?

Please let me know the situation, how timeout occurs.

There are two places for timeout of pinpad input.

  (1) Reader's timeout for execution of PC_to_RDR_Secure message.

      Host specifies this timeout.  Currently, we don't use this
      feature.  The reader waits validation key (Enter) pressed (with
      no timeout).

  (2) Host PC's timeout for waiting reply of RDR_to_PC_DataBlock.

      This is low-level thing.  In GnuPG's ccid-driver, it's 30 secs.
      I think that the reader usually sends back "timer extension"
      to host PC to ask waiting again (before the expiration).

      I will check for PC/SC.
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