Re: [Cfrg] Trouble reproducing mulX_POLYVAL() test vector from RFC 8452 Appendix A

[Adam Langley <[e-mail]>]

On Thu, Sep 5, 2019 at 1:05 PM Tony Arcieri <[e-mail]> wrote:

> I've been trying to implement mulX_POLYVAL() as described in RFC 8452
> Appendix A:
>
> https://tools.ietf.org/html/rfc8452#appendix-A
>
> It says:
>
> Given the 16-byte string 01000000000000000000000000000000, [...]
>
> mulX_POLYVAL of that string is 02000000000000000000000000000000.
>
> As a more general example, given 9c98c04df9387ded828175a92ba652d8, [...]
> mulX_POLYVAL of it is 3931819bf271fada0503eb52574ca5f2.
>
>
> However, I am getting 3931819bf271fada0503eb52574ca572 (highest bit
> unset). I'm not sure if it's a problem with my code, or the test vector.
>

Ah fuck, so do I. Indeed, even if I revert my test code back to the point
in time when I wrote that, I still get the same answer. I fear that it's a
transliteration error: I may have been editing the XML on a different
machine than the one that I had the code on and the '7' looked like an 'f'.

The IETF doesn't fix RFCs, but could you report an errata on it and then I
think I can mark it verified.


Cheers

AGL