OpenPGP card specification enhancement for ECDSA support
gniibe at fsij.org
Mon Mar 4 04:03:51 CET 2013
Thank you very much for your comments and references.
On 2013-03-02 at 14:30 +0100, Achim Pietig wrote:
> BSI defines the following for PubKeys:
> The conversion of Elliptic Curve Points to octet strings is
> specified in . The uncompressed format SHALL be used.
> Data Object Abbrev. Tag Type Certificate
> Object Identifier 0x06 Object Identifier m (mandatory)
> Prime modulus p 0x81 Unsigned Integer c (conditional)
> First coefficient a 0x82 Unsigned Integer c
> Second coefficient b 0x83 Unsigned Integer c
> Base point G 0x84 Elliptic Curve Point c
> Order of the base point r 0x85 Unsigned Integer c
> Public point Y 0x86 Elliptic Curve Point m
> Cofactor f 0x87 Unsigned Integer c
Thank you for the reference.
> German eGK (e. g.) uses Tag 06 and 86 only, I prefere this for the
> Open PGP card also.
> The response of GENERATE ASYMMETRIC KEY PAIR will be:
> 7F49 xx
> 06 xx OID
> 86 xx Elliptic Curve Point
With this format, I will update my work of GnuPG experimental patch
and Gnuk experimental implementation.
> For key import we have to check if this information is enough or if
> we should use additional parameters (see conditional information in
> BSI table).
I think that OID is enough and Public point is optional for key
import. Private key data (scalar value) is needed.
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