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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Sun, 31 Mar 2019 20:18:13 +0200
Message-ID: <CAHmME9o+HqyrXX403bSXJX4Xs0dsZ9Qo=owiu7QGzBbaLQWZag@mail.gmail.com>
Subject: Re: [PATCH net-next v9 00/19] WireGuard: Secure Network Tunnel
To:     Eric Biggers <ebiggers@kernel.org>
Cc:     Herbert Xu <herbert@gondor.apana.org.au>,
        Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Netdev <netdev@vger.kernel.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        David Miller <davem@davemloft.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Samuel Neves <samuel.c.p.neves@gmail.com>
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On Sat, Mar 30, 2019 at 6:53 AM Eric Biggers <ebiggers@kernel.org> wrote:
> poly1305-simd is among the failing algorithms because it loses carry bits when
> handling long "all 0xff bytes" inputs.  poly1305-avx2-x86_64.S is definitely
> broken, and poly1305-sse2-x86_64.S *might* be too.  I am working on a patch...

Yea.... yikes. I'm kind of souring on this plan of having to deal with
that code in Zinc, versus the extensively studied, fuzzed, and
scrutinized code from Andy. Subtle carry bugs like that are kind of a
testament to my overall plan of preferring formally verified or
heavily used implementations to bespoke ones. This stuff is hard to
get right.

Jason