From: Eric Hughes <hughes@soda.berkeley.edu>
Date: Wed, 11 Nov 92 08:24:36 PST
To: crunch@netcom.com
Subject: Random number generators
Message-ID: <9211111624.AA08843@soda.berkeley.edu>
MIME-Version: 1.0
Content-Type: text/plain



There seems to be some confusion over this random number device.

Perry Metzger forwarded me some information about Newbridge
Microsystems and the part number of a chip that made random numbers.
At the crypto BOF at hackers I mentioned that there was a need for a
hardware random number generator and that I knew of some chip to do
it.  John Draper, who was there, expressed a desire to work on such a
device.  I forwarded him the information about the chip.

What I didn't know was the cost or design of this chip.  It appears to
use a radioactive source to make random numbers.  This may account for
the cost.  In any case, it is likely that most applications don't need
this kind of chip.

What is needed, though, is _some_ kind of chip.  John Draper is eager
to manufacture such a device, once we have a design.  Would those
people willing to help on this design please get in touch with him
directly and start a conversation about it.  The conversation could
reasonably be discussed on the list, if enough are interested.

FYI, random numbers are used generally to create single-use session
keys in a wide variety of crypto protocols, including Diffie-Hellman
key exchange.  Hardware random number sources will be a standard
component of all computers in the near future.

As far as the design of the device itself goes, the numbers that come
out of it don't have to be fully random.  Non-randomness can be
corrected in software.  Two characteristics of the output, though will
help such correction.  First, the number of ones and zeros should be
the same.  Not only is this useful for correction, but it is easy to
do in hardware.  Second, effort should be made to make sure that the
generator does not pick up cyclic noise from its environment.  This
means attention to coupling, shielding, and packaging.  No extra
expense, likely, but definitely to be thought about some.

Eric