Supporting fixed length keypad input

[NIIBE Yutaka]

On 2013-03-02 at 15:35 +0100, Achim Pietig wrote:
> PC/SC V2: Interoperability Specification for ICCs and Personal Computer Systems, Part 10 IFDs with Secure PIN Entry Capabilities, Revision 2.02.09 November 2012
> Secoder 2: from german banks (GeldKarte), not public available

Thanks for your references.

> If the support of readers for alpha passwords with variable length
> is too complex, a next version of the OpenPGP card may support PIN
> 2-block too, but then an algorithm ID or a usage flag in Extended
> capabilies is needed. What do you think?

No, the support of readers (for alpha passwords and/or with variable
length) is not that difficult, in terms of GnuPG implementation.  From
users point of view, it is a bit complicated to configure fixed length
PIN input, though.

My own problem was one of my readers doesn't support variable length
PIN input.  And I thought that such readers were common.  Anyway, such
readers are supported by fixed length PIN input.

Adding format 2 PIN block make sense if:

   (1) Readers which don't support variable length PIN input are common.

   AND

   (2) Readers work well for encoding nibbles for PIN input.

   AND

   (3) Users wants no configuration for fixed length PIN input.

Given the condition (1) is (or will soon be) not true any more, adding
format 2 PIN block is not worth.  Users deserve to be required to
configure for not-so-common readers.
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