[149119] in cryptography@c2.net mail archive
Re: [Cryptography] cheap sources of entropy (Bill Frantz)
daemon@ATHENA.MIT.EDU (Peter Trei)
Mon Jan 20 11:07:03 2014
X-Original-To: cryptography@metzdowd.com
Date: Sun, 19 Jan 2014 13:58:28 -0500
From: Peter Trei <petertrei@gmail.com>
To: cryptography@metzdowd.com
Errors-To: cryptography-bounces+crypto.discuss=bloom-picayune.mit.edu@metzdowd.com
--===============4317783603138584927==
Content-Type: multipart/alternative; boundary=047d7bf15fc84c8e4f04f0575ca8
--047d7bf15fc84c8e4f04f0575ca8
Content-Type: text/plain; charset=ISO-8859-1
Bill Frantz <frantz@pwpconsult.com> wrote
>
>
> On 1/18/14 at 12:17 AM, iang@iang.org (ianG) wrote:
>
> >Jon Callas (I think) a long time ago suggested pointing your cheapo USB
> >camera at a photographer's grey card in low light. The theory is that
> >the cells in a camera seek for information and if they don't see
> >something that is worth reporting, it drives them a little tipsy. The
> >claim is that this effect can drive them into some form of quantum
> >uncertainty.
>
> I think what is happening here is the effective ISO is being
> pushed up by the low light so there is a lot of noise in the
> amplifiers used to read out the sensor cells. What you are using
> is thermal noise in the amplifiers. You get a lot of readings in
> one photo, and it should be a good source.
>
One thought I've had on this applies only to wearables (smartphones,
mainly;
many contain accelerometers which allow them to determine orientation,
motion, etc.
Since these accelerometers are also used in very low power gadgets such
as fitness activity monitors, (Fitbit, etal), where they operate
continuously,
it seem plausible that they are cheap (in power terms) to run.
My suspicion is that these can act as a low-bandwidth source of entropy,
by the usual mechanisms involving timing of successive transitions.
producing
randomness which can be added to the pool.
Any thoughts? I expect this has been suggested before.
pt
--047d7bf15fc84c8e4f04f0575ca8
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
<div dir=3D"ltr"><br><div class=3D"gmail_extra">=A0
Bill Frantz <<a href=3D"mailto:frantz@pwpconsult.com">frantz@pwpconsult.=
com</a>> wrote<br><div class=3D"gmail_quote"><div>=A0</div><blockquote c=
lass=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;=
padding-left:1ex">
<br>
<br>
On 1/18/14 at 12:17 AM, <a href=3D"mailto:iang@iang.org">iang@iang.org</a> =
(ianG) wrote:<br>
<br>
>Jon Callas (I think) a long time ago suggested pointing your cheapo USB=
<br>
>camera at a photographer's grey card in low light. =A0The theory is=
that<br>
>the cells in a camera seek for information and if they don't see<br=
>
>something that is worth reporting, it drives them a little tipsy. =A0Th=
e<br>
>claim is that this effect can drive them into some form of quantum<br>
>uncertainty.<br>
<br>
I think what is happening here is the effective ISO is being<br>
pushed up by the low light so there is a lot of noise in the<br>
amplifiers used to read out the sensor cells. What you are using<br>
is thermal noise in the amplifiers. You get a lot of readings in<br>
one photo, and it should be a good source.<br></blockquote><div><br></div><=
div>One thought I've had on this applies only to wearables (smartphones=
, mainly; <br>many contain accelerometers which allow them to determine ori=
entation, <br>
motion, etc.<br><br></div><div>Since these accelerometers are also used in =
very low power gadgets such<br>as fitness activity monitors, (Fitbit, etal)=
, where they operate continuously,<br></div><div>it seem plausible that the=
y are cheap (in power terms) to run.<br>
<br></div><div>My suspicion is that these can act as a low-bandwidth source=
of entropy,<br></div><div>by the usual mechanisms involving timing of succ=
essive transitions. producing<br>randomness which can be added to the pool.=
<br>
<br></div><div>Any thoughts? I expect this has been suggested before.<br><b=
r></div><div>pt<br><br></div></div></div></div>
--047d7bf15fc84c8e4f04f0575ca8--
--===============4317783603138584927==
Content-Type: text/plain; charset="us-ascii"
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
_______________________________________________
The cryptography mailing list
cryptography@metzdowd.com
http://www.metzdowd.com/mailman/listinfo/cryptography
--===============4317783603138584927==--
