OpenPGP card specification enhancement for ECDSA support
openpgp at brainhub.org
Tue Mar 5 06:44:51 CET 2013
I agree that you would want to support uncompressed ECC key
representation at least because you never know where a key came from.
Having said this, GnuPG should change the key generation to generate
"compliant" keys all the time. I do this in my software. There is no
reason not to do so. This gives an option to use an efficient
representation down the road, but that's not a requirement. One can
still encode a compliant key per RFC6637 (uncompressed).
I can volunteer to write a patch for the compliant key generation for
GnuPG when I find time.
On 03/03/2013 05:19 PM, NIIBE Yutaka wrote:
> Hello Andrey,
> On 2013-03-02 at 18:12 +0900, NIIBE Yutaka wrote:
>> On 2013-03-01 at 11:02 -0800, Andrey Jivsov wrote:
>>> Please consider using the compact representation of an ECC point:
>>> http://tools.ietf.org/html/draft-jivsov-ecc-compact with the OpenPGP card.
>> Thank you very much. I didn't know this document. All that I had
>> known about compression was x + (1-bit of y).
> I considered again.
> For new keys, we will be able to take advantage of this compact
> representation. But, there are already ECDSA keys out there.
> I will limit key space for Gnuk for new keys, so that keys generated
> on Gnuk Token can be represented by the compact representation. But,
> note that most users of Gnuk use writekey command, generating keys on
> host PC.
> I think that Gnuk Token should not limit key space for writekey
> command (host PC -> Gnuk Token), but should accept keys of other half
> space for inter-operablity.
> Speaking for GnuPG, same argument could be applied.
> It is true that there has been no released versions which support
> ECDSA yet. But, it should handle any keys by any OpenPGP ECC
> implementations. Besides, GnuPG supports SSH and X.509. With the
> possibility of 50%, existing keys of ECDSA couldn't be represented by
> the compact representation. I think that GnuPG should handle both of
> the compact representation and the uncompressed representation.
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