Security update of nettle

[Ola Lundqvist]

Hi Niels

Thank you for this instruction. Yes the modulo check is rather easy to
check. Definitely easier with your instruction than without.

However I was referring to the side-channel problem that was reported
in the CVE and not to the unintended side-effect of the correction.

Do you know a way to trigger the problem reported in the CVE, please
let me know.

// Ola

On Tue, Aug 9, 2016 at 2:27 PM, Niels Möller <nisse at lysator.liu.se> wrote:
> Ola Lundqvist <ola at inguza.com> writes:
>
>> I have not tried to reproduce the potential side-channel issue as that one
>> is rather hard to trigger. If anyone know about a tool for that, please let
>> me know.
>
> One basically has to patch a valid private key and clear the least
> significant bit of p or q.
>
> With lsh, sexp-conv -s hex should convert an unencrypted private key
> into a form suitable for editing in a text editor. After editing,
> convert back to canonical (binary) syntax, again using sexp-conv.
>
> For key files as used with gnutls, Hannu suggested using
> https://github.com/google/der-ascii
>
> Regards,
> /Niels
>
> --
> Niels Möller. PGP-encrypted email is preferred. Keyid C0B98E26.
> Internet email is subject to wholesale government surveillance.



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