New entropy source proposal.

[Garrett Wollman]

<<On Mon, 07 Mar 2005 16:09:48 +0000, Mark Murray <markm at FreeBSD.ORG> said:

> Did you have a noise source connected? I generated 1MB of data and it was not
> very random at all. "hexdump -C data" showed the data was very poor indeed.

The usual noise source is thermal noise in the machine itself.  The
process that I've heard described involves:

0) Disconnecting any input sources.
1) Turning the input gain all the way up.
2) Taking only the least-significant bit of each sample.

In order to use this in FreeBSD, we would probably want a compile
option in the sound drivers to disable their use for other purposes
(e.g., generating sound).

-GAWollman