[PATCH] g10: Fix ECDH secret compressed/uncompressed format

[NIIBE Yutaka]

Hello,

Thank you for your patch.  Please clarify some points.

On 10/24/2016 06:43 PM, Arnaud Fontaine wrote:
> * g10/ecdh.c (pk_ecdh_encrypt_with_shared_point): Improve detection of
> the uncompressed format, add leading zeros to the compressed format.

I interpret that "the compressed format" means x-coordinate only
in Jivsov's proposal:

    https://tools.ietf.org/html/draft-jivsov-ecc-compact-05

For ECDH, we don't need to care about the key generation constraint.

I think that it is good for OpenPGP card specification to address
the point format representation:

    04 || X || Y

    or

    X only, with no prefix

I think that the original compressed format of SEC (02 or 03 prefix)
is covered by the patent by HP.
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