Certain security applications ask you to move your mouse for a while in order to obtain some random data. This may be cheap but it produces random data at a very low rate, so it's not practical for my one-time-pad.

What are some good ways to produce a lot of truly random data fast, and at a low cost?

How about a video camera pointed at something random like rain?

I highly recommend reading this paper for some ideas and/or inspiration.

Thanks.

I have found many options for a higher bandwidth, from physical products at $70-$350, to free software that harvests entropy from cameras and microphones. These two seem the most attractive so far:

http://rwmj.wordpress.com/2010/08/04...ber-generator/

http://www.vanheusden.com/ved/

A thorough-looking overview:

http://world.std.com/~reinhold/truenoise.html

People using cameras do it in the dark, or with the lens capped, by removing the infrared filter and sensing black-body radiation as the source of noise. But why not regular videos of chaotic things like crowds of people or rain? Surely after 20 years of mpeg there must be people who know enough about imaging to isolate the pure noise?