To: >Internet:cypherpunks@toad.com This posting is in response to Liam's earlier message on creating a random number generator using a zener diode. I breadboarded such a circuit over year ago and it worked fine. Zener diodes, operated in their zener region with a reverse voltage generate electrical noise much like a "noise diode". This can be amplified and shaped using a single quad op amp package to create what appears to be a very random data stream. Best way to use this would be to shift it into an eight bit latch before reading the parallel port. Depending on design, it's operation is much (MUCH) faster than a pseudo random number generator written in software. It can fill a floppy disk so fast that the main limitation is the writing speed of the disk drive. A simple XOR with the message text is enough to create an unbreakable cyphertext. Problem is, that both parties have to have exact copies of the random numbers since they cannot be regenerated as with pseudo random numbers using a key. What is needed is a way to encrypt the random numbers so that they can be sent to someone else to use. This would be hard to decode, because it would be difficult to know when success had been achieved. If it is being tested against a message text, the loss of one byte shifts everything to that the text becomes gibberish again. I'm glad Liam brought this up. It is a good way to produce an absolutely unbreakable code. This, providing the design is good and no patterns are allowed to appear (introduced by amplifier oscillation or nearby noise sources) in the generated numbers. If there is any interest out there perhaps we (Liam or I) could produce a few for testing.