At 10:19 PM -0500 11/15/2000, Rich Salz wrote:
>I'm putting together a system that might need to generate thousands of RSA
>keypairs per day, using OpenSSL on a "handful" of Linux machines. What do
>folks think of the following: take one machine and dedicate it as an entropy
>source. After 'n' seconds turn the network card into promiscuous mode, scoop
>up packets and hash them, dump them into the entropy pool. Do this for 'm'
>seconds, then go back to sleep for awhile. The sleep and wake times are
>random numbers. Other systems on the newtwork periodically make an SSL
>connection to the entropy box, read bytes, and dump it into their /dev/random
>device.
>
>Is this a cute hack, pointless, or a good idea?
> /r$
I think it is a bad idea for two reasons. First, it is hard to
characterize the entropy in the packet stream. Second, being
connected to a network makes the noise generating machine vulnerable
to attack. Compromised noise generators are very difficult to detect
and devastating to security.
I think you would be far better off using a true noise source, or,
better two of them. See
http://world.std.com/~reinhold/truenoise.html for some suggestions.
Attach it to a Linux box dedicated to key pair generation and keep
the machine off the network entirely. If the keys are going into
tokens, load the tokens from the key gen machine. If the keys are
being used in other software, encrypt them and transfer them via
floppy or some simple serial link.
The key gen machine should be physically isolated and secured as
well, perhaps a laptop in a safe.
Arnold Reinhold
