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Date: Wed, 19 Mar 2014 09:27:57 +0900
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To: Ferenc Kovacs <tyra3l@gmail.com>
Cc: Adam Harvey <aharvey@php.net>, =?UTF-8?Q?Rouven_We=C3=9Fling?= <me@rouvenwessling.de>, 
	PHP internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a1135f7acdaa21804f4eabb04
Subject: Re: [PHP-DEV] [VOTE] Timing attack safe string comparison function
From: yohgaki@ohgaki.net (Yasuo Ohgaki)

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Hi all,

On Wed, Mar 19, 2014 at 3:56 AM, Ferenc Kovacs <tyra3l@gmail.com> wrote:

> > > > From benchmark result, overhead for timing safe comparison is
> negligible
> > > > with byte by byte comparison.
> > > > I would like to see timing safe "=3D=3D=3D" for 5.6, if it's possib=
le. (=3D=3D
> could
> > > > be timing safe, too)
> > > >
> > > > Is anyone working on it?
> > >
> > > I don't know if someone else is, but I am not.
> >
> > I'm not in favour of this =E2=80=94 identity doesn't imply timing safet=
y, and
> > I think we should keep operators as performant as possible.
> >
>
> Agree and afair it was explicitly stated as out of scope for this rfc.
> (sorry for not merging this sooner, thanks Adam for thaking care of this)=
.
>
Benchmark reveals performance issue is negligible.

Regardless of where it is implemented, simple byte by byte compare is the
best.
We may ignore length leak at all. It's simpler (less risk) and faster.

It's better to make =3D=3D=3D timing safe like Python, since it would
be far less risks than dedicated API, but we may consider this later if the
risk is
getting greater.

I need API to be exposed so that I can use it anywhere in PHP.
Please make a PHPAPI.

--
Yasuo Ohgaki
yohgaki@ohgaki.net

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