Newsgroups: sci.crypt Path: cactus.org!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!usc!crash!kephart From: kephart@crash.cts.com (Wray Kephart) Subject: RNG's Organization: CTS Network Services (CTSNET/crash), San Diego, CA Date: Wed, 2 Feb 1994 12:47:44 GMT Message-ID:Summary: random number sources Keywords: rng, prng Sender: kephart@crash.cts.com Nntp-Posting-Host: crash.cts.com Lines: 38 I've been browsing this newsgroup for a month or two and have seen posts for PRNG's, hardware RNG's, and recently a Nuclear RNG discussion. Random phenomena in electronics are fairly common, e.g., diode noise or oscillator phase jitter to name two. The difficulty is not in locating a suitable source of random electrical events, rather it is the measurement of the events without perturbing the 'system' or introducing skew into the data as a result of making the measurement. One example that comes to mind was a project to interface a digital random sequence generator chip to a PC. I buffered the chip and connected it to the Rx line of the RS-232 port. When a random 1 or 0 was required, you read the serial port. WRONG! The chip output was random however there existed a _slight_ difference between the rise and fall times of the buffer. This gave the data a slight skew towards 1's (slower rise, faster fall). The message was: asynchronous sampling of a random event is not necessarily valid depending on your measurement system/interfaces. Be careful. I've been working with development, debug, and validation of random sequence hardware for several years. My advice to anyone seriously requiring a source of truly random numbers is to buy the commercial version of a 'randomizer' chip. Last I looked, they are manufactured by both Rockwell and Hughes. The price (in quantity) was around $150.00 for Class B devices. I believe the specs for randomness are not as stringent as for the military versions. ----------------------------------------------------- --- The opinions expressed above are not my own --- --- If you want to know what I think --- --- it will cost you --- ----------------------------------------------------- ---> Technical and data = kephart@sirena.hac.com <--- ---> General & Business = kephart@lyra.hac.com <--- ---> Personal = kephart@crash.cts.com <--- -----------------------------------------------------