Re: [Cfrg] I-D Action: draft-irtf-cfrg-hpke-02.txt

[Ilari Liusvaara <[e-mail]>]

On Fri, Dec 06, 2019 at 07:11:01PM -0800, Benjamin Kaduk wrote:
> On Wed, Dec 04, 2019 at 11:29:53AM +0000, Michael Scott wrote:
> > 
> > Some feed-back: It would be a good idea to explicitly warn the reader that
> > the X25519/X448 keys are actually in little-endian format, whereas for
> > P256/521 they are big-endian.
> 
> I think the general idea is that X25519 and X448 APIs act on fixed-length
> byte strings and you are not supposed to care about the internal structure
> or encoding.  

Correct, from RFC7748:

"Although the functions work internally with integers, the inputs and
outputs are 32-byte strings (for X25519) or 56-byte strings (for X448)
and this specification defines their encoding."


-Ilari