From: "Mike Johnson" <exabyte!smtplink!mikej@uunet.UU.NET>
Date: Tue, 5 Oct 93 13:15:00 PDT
To: cypherpunks@toad.com
Subject: Re: Need Suggestions for Random Numbers
Message-ID: <9309057498.AA749854878@smtplink.exabyte.com>
MIME-Version: 1.0
Content-Type: text/plain



>I have seen here and elsewhere descriptions of hardware random
>number generators (Geiger counters measuring random nuclear
>decay, microphones picking up background hiss etc.), but I need
>something that can be implemented entirely in software.

There is no such thing as real random numbers implemented purely in software.
The best you can do in pure software is a cryptographically strong
pseudorandom number sequence, started at a random point -- like continually
feeding the output of DES back to its input.

>Also, can anyone recommend a statistical test for randomness, or
>for detecting repeating patterns in a "random" file?

Try compressing the file with PKZIP & see if it gets smaller.  If it does, it
flunks.  If it doesn't, it may still have some patterns to it.

>What would be a good source of random meaningless sound? (an
>quiet room, ocean surf, repeats of Gilligan's Island, old
>presidential speeches (pick your favorite president). :-)

Not bad, but be sure to compress the output to remove the regular patterns of
the surf, etc, then use the compressed output -- after stripping off any
headers applied by the encryption program.