On Thu, 17 Oct 2002, Morlock Elloi wrote:
Landon Noll has done some interesting work taking a cheap PC camera and keeping it in the dark. The CCDs try to adjust, and you get noise.
I's suggest a hi-fi video digitizer with analog input. CCDs have dirty randomness.
Most modern USB cams (I use Aiptek APC 400, which is dirt cheap and plug and play under Linux) are CMOS, and have very dirty randomness (switch off jpeg compression, wrap it in aluminum foil, wait a little for the cam to adjust, and make a diff of a few pairs of frames). However, they're more noisy than CCD, and the spatial bias gets killed by the cryptohash.
Rather than compressing 8:1 using byte parity, I'd recommend using a hash function, such as MD5 or SHA, which means that every bit of the input can tweak any bit of the output.
Well, each of 8 bits of byte affect its parity. It's just the different initial block size. But tastes vary.
Actually, you're making a lot of random assumptions in your treatment of the raw video, which is a no-no even in the crypto sham we're engaging in. You'd do much better if you'd just use a SHA-1 on a few lines (or estimate (measure), how many lines you need for some 160 bits of raw entropy, and double that for good measure) of raw video. Imo it might be arguably safe/make sense to throw away a few of highest significant bits which are always zero, and paste the rest together, destilling entropy. However, you can actually lose entropy if your setup is very noisy/has a threshold and you're blindly catting only LSBs. This won't happen if you use SHA-1 blindly on raw video.