Hardware produced white noise

Hi,

i'm new here.

I'm looking for a hardware device (computer card) producing digitized (true) white noise.

Could you kindly suggest me something?

Thanks in advance!

A quick google found this

Or perhaps a book

Or take bits from any biased (but apparently random) source, such as an audio input channel without any input, and apply a Von Neumann extractor to the resulting bit-stream.

Thank you very much, Mr. Salem!

I was just interested, what cryptography experts say on this subject.

Have a nice day !...

I don't have a clear picture, of what the original poster is seeking.

White noise is defined in spectral terms, and is not physically realizable. For engineering purposes, many "white noise" generators have been made that adequately approximate white noise over some defined bandwidth.

Useful generators of this type can be made without using any digital processing. For decades, however, there have been digital white noise generators (my first recollection of an IC for this purpose dates to around 1977).

Digital white noise generators DO NOT need to be unpredictable; the most common designs are in fact strictly periodic (with a very long period, so that the appreciable harmonics are at frequencies below the required band).

This is very different from cryptographic "random number" generation, which must be impractical for an adversary to predict.

A random bit sequence generator intended for cryptography could indeed be used to create a "white noise" signal, but it would be an expensive and slow method.

Cryptographic random bit sequences, and white noise signal generation, while theoretically linked, are in practice quite different applications.

Thank you Mr. Mah$us for your answer.

I mean, of course, cryptographic random bit sequences generator.
And "true" means that its result cannot be predicted by any algorithm.

I don't want to create "white noise" signal, but to use such generator for OTP cryptography.

Probably, there are many such devices on market.

The perfect solution for me, would be some USB device,
with some software (say, library) that could be "included" in a C program.

Thanks in advance for all suggestions.

Read http://www.ietf.org/rfc/rfc1750.txt

Very instructive. Thank you.