true random numbers : Java Glossary

Creating true random numbers requires considerably more effort than pseudo-random ones. You need to build a peripheral that is a true random number source. This would be useful for creating one-time cryptography pads, and also in various simulations. Here are several ways it could work:

• Monitoring the timing between click of radioactive (such as the tiny piece of Americium in a smoke detector) registered by a crude Geiger counter.

  Aware electronics

  sells the RM-60 model for  $150.00 USD . The RM-60 produces a down-going 75-90us pulse each time it detects a radioactive decay particle. The times between clicks follow a Poisson distribution. You could expect about 300 counts per second with that exposed bit of Americium. If you buy one, ask them to throw in a free copy of Aw-rand.exe to use their Geiger counters to create files of random numbers. Intel and AMD (Advanced Micro Devices) are buying them to generate random numbers.

  You could use System. nanoTime to measure the time between clicks. The trick then it to convert this into uniformly distributed bytes with no bias. Crudely, you could just use the low order 8-bits. You would discard ticks that came too soon on the heels of the previous one. You can use XOR (exclusive OR) to scramble the high and low bytes of a number together to create a more random byte that depends on both high and low byte. Any bias or patterns in the generated gibberish could be exploited by the code cracker.

  There is a mathematical effect to watch out for too. There are more measurements beginning with 1 in the universe than there are that begin with 9.

• Similar to above, but count alpha particles emitted by a thorium Coleman lantern mantle.
• Noisy transistor, or transistor bank. This is what Turing wanted in the original Eniac.
• Monitoring the precise timing between the user’s keyclicks. This is how ENCRYPT works.
• Measuring some irregular biometric function.
• Buy an Orion Random Number Generator.
• Custom random number generator card. It contains a high frequency 8-bit circular hardware counter that just increments rapidly. Whenever a random click occurs, you metaphorically stick your finger in the wheel of fortune and sample the value of the counter. If a click comes sooner than two complete revolutions of the "wheel"/counter, you discard that click.
• Use the random.org method. A radio is tuned into a frequency where nobody is broadcasting. Just hook up your stereo to the input of your sound card. The atmospheric noise picked up by the receiver is fed into a workstation through the microphone port where it is sampled by a program as an eight bit mono signal at a frequency of 8 kHz. The upper seven bits of each sample are discarded immediately and the remaining bits are gathered and turned into a stream of bits with a high content of entropy. Skew correction is performed on the bit stream, in order to insure that there is an approximately even distribution of 0s and 1s using transition mapping. Even though random.org serves random numbers, you can’t use them for cryptography, since they are not securely delivered, and they are public property.