[Cryptography] The ultimate random source
huitema at huitema.net
Wed Feb 19 02:09:08 EST 2014
-----BEGIN PGP SIGNED MESSAGE-----
>> I have a solution to the random number generator problem that can be built for about $50 and is completely verifiable.
> It works just as well, perhaps better, if you put a lens cap on the camera. The ritual with the smarties just makes you feel better.
If you rely on a capped camera to generate white noise, you may be out for a surprise with at least some cameras. There is a lot of filtering and processing that happens on board the camera itself, e.g. conversion from Bayer pattern to YUV or RGB, firmware that enhances the image, compression to JPEG before transmission on the USB bus, cropping and resizing on demand, etc. I would not be surprised if some cameras, when capped, just transmit a black image.
The camera is designed to produce an image that represents the scene in front of it. There are two sources of randomness that are "built in," the randomness of the scene itself, and the randomness of the position of the camera in the scene. A few degrees cause a lot of pixels to shift, a live scene has lots of varying bits. I would rather rely on that instead of making assumptions on the amount of filtering built in the firmware.
- -- Christian Huitema
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.20 (MingW32)
Comment: Using gpg4o v188.8.131.5274 - http://www.gpg4o.de/
-----END PGP SIGNATURE-----
More information about the cryptography