From: jp@jep.pld.ttu.ee (Jyri Poldre)
Date: Mon, 20 Jun 94 08:28:12 PDT
To: cypherpunks@toad.com
Subject: PC RND generator based on physical  random
Message-ID: <9406201523.AA21364@jep.pld.ttu.ee>
MIME-Version: 1.0
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What you need is natural source of random. I have used clocking
higher speed quarz generator with
lower speed (10 x is ok ) unstable frequency oscillator  
and then taken parity of the result (4-5 bits is enough for most situations, depends of cource on distribution of LF generator values) . Variable Freq. 
oscillator  is RC and higher quarz. Now as we are not willing to 
give up card slot (and PCB board area ands so on ) for just RND generator
maybe it is good to find existing source of random in PC itself. 
So - do we have RC generator in PC? YES. We have 4 of them, to be exact.
Most of us do not make much use of these ports, because most games do not support them correctly. But anyhow, joystick ports are there. IO card costs 10$ if you have not already got one. So I propose scheme for PC RND generator:
1. Make LF generator using Joystick ports
2. Use HF oscilltor of PC clock ( Program Execution, if any interrupts occur,
   it is no problem).
3. Find out the distribution of LF oscillator and calculate the needed Parity
   filter size. 
   ( By parity filter I concider parity values of N last bits)
4. Use it