Date: Sun, 11 Dec 2016 16:30:27 +0100
From: Andrew Lunn <andrew@lunn.ch>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: linux-mips@linux-mips.org, Netdev <netdev@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Dan =?iso-8859-1?Q?L=FCdtke?= <mail@danrl.com>,
        Willy Tarreau <w@1wt.eu>,
        =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= <mans@mansr.com>,
        Hannes Frederic Sowa <hannes@stressinduktion.org>,
        WireGuard mailing list <wireguard@lists.zx2c4.com>,
        Greg KH <gregkh@linuxfoundation.org>, Felix Fietkau <nbd@nbd.name>,
        Jiri Benc <jbenc@redhat.com>, David Miller <davem@davemloft.net>
Subject: Re: Misalignment, MIPS, and ip_hdr(skb)->version
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> 3. Add 3 bytes of padding, set to zero, to the encrypted section just
> before the IP header, marked for future use.
> Pros: satisfies IETF mantras, can use those extra bits in the future
> for interesting protocol extensions for authenticated peers.
> Cons: lowers MTU, marginally more difficult to implement but still
> probably just one or two lines of code.

I'm not a crypto expert, but does this not give you a helping hand in
breaking the crypto? You know the plain text value of these bytes, and
where they are in the encrypted text.

      Andrew