[82335] in Cypherpunks
Re: Sources for stego images, was re: Laying PipeNet
daemon@ATHENA.MIT.EDU (tzeruch@ceddec.com)
Mon Jun 23 18:40:29 1997
Date: Mon, 23 Jun 1997 18:01:30 -0400
From: tzeruch@ceddec.com
To: Steve Schear <azur@netcom.com>
Cc: Adam Back <aba@dcs.ex.ac.uk>, cypherpunks@Algebra.COM
In-Reply-To: <v03102804afd38b324730@[10.0.2.15]>
Reply-To: tzeruch@ceddec.com
On Sun, 22 Jun 1997, Steve Schear wrote:
> >That's the major problem with images, you need to generate your own.
> >Unless you fancy writing an image enhancement system, and analyse the
> >algorithms in existing systems to ensure that randomness is
> >introduced.
> >
>
> There are plenty of Net-cams watching traffic or sunsets around the world.
> Since these images tend to change a bit from frame to frame they could
> cheaply and reliably provide the sorts of images which are ideal for stego.
> I'm not sure if you can frame-grab from such a changing Web page with the
> current browser features, but this should be a significant hurdle.
Or, set up your own webcam "to watch your coffee pot twice a minute" or
something. Merge the crypto stream through the gifs after tweaking the
brightness and contrast to avoid 0 and 255 (a light fixture with a pattern
of 254/255 values gets suspicious, and is not from thermal noise - a
"problem" with monochrome quickcams for night photography).
Then do something like
lynx -source webcam.x.y/images/coffee.gif | destegodecrypt >>reconstruct
every 30 seconds (with some kind of dropout correction). [lynx is a
textmode browser that works well for these types of things].
Or even an AVI for both video and sound stego.
