Re: Video as a source of randomness

[tcmay@got.net (Timothy C. May)]

At 6:02 AM 11/2/95, Andrew D. Isaacson wrote:
>A thought just occurred to me...
>
>How useful would it be to use a video stream as a source of random input
>to something like /dev/random?  I'm thinking along the lines of a
>Connectix QuickCam (sp?) or the cool videocam that comes with the Indy.
>It seems to me that the picture recieved by a camera sitting atop a
>monitor would be quite unpredictable. (relatively) High bandwith, too.
>Even if the entropy in a video signal is low, the high bandwidth would
>seem to make up for it.
>
>Struggling to keep my head above the crypto tide,

Digitized video input, especially from something like a noisy channel (t.v.
channel, for example), is quite likely to produce a lot more entropy bits
per second than nearly any of us ever need. (One's PGP key could be seeded
in a fraction of a millisecond, for example.)

The issue is that most people don't need this number of entropy bits per
second, and that most people don't have video inputs. (And those that do
may not have them hooked up and ready to go.) One of the basic ideas we
have had, as Cypherpunks, is to encourage widespread methods. Any methods
that need special hardware tend to not get widely used.

Audio, video, disk timing, and all sorts of other sources of physical
randomness are useful to have, but most people either won't have the right
configuration or won't configure their systems so as to use their
configuration.

--Tim May, who has both audio and video digitizers built into his Power
Macintosh 7100av, but notes that none of the crypto programs he uses has
any provision for using them, and so he doesn't use them for crypto
purposes.

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