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I am looking for a method of making random numbers that is off-line and is also independent of specialist equipment like a Geiger counter.

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closed as too broad by e-sushi, owlstead, figlesquidge, Gilles, rath Apr 26 at 16:18

There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.If this question can be reworded to fit the rules in the help center, please edit the question.

a deck of cards $\;$ –  Ricky Demer Apr 23 at 8:23
Dice are specialist equipment? –  Thomas Apr 23 at 8:47
Flip a coin? Cards makes the most sense - although make sure to shuffle them sufficiently many times using a riffle shuffle (other shuffles are either equivalent or worse) to ensure propper randomisation –  figlesquidge Apr 23 at 8:55
What kind of number? 0/1? 1..6? π? –  CL. Apr 23 at 9:20
Do you expect cryptographically secure randomness, or merely some pseudo-random numbers? Do you assume the human brain to be “specialist equipment” or not? How will you solve the issue that an averagely trained human brain can not remember a sequence of 100 random numbers? Fun aside – your question is a mixture between “not a real question” and “too broad”. (I’m not sure if we even handle “lack-of-creativity” at Crypto.SE.) In the end, I decided to flag your question for being too broad. –  e-sushi Apr 23 at 19:33
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1 Answer 1

Do a long jump, measure the distance in millimeters, take it modulo 10.

Repeat 100 times.

Another idea: use clock timer that shows milliseconds, start it and then turn off after some time, look at the last digit.

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Too easy to measure incorrectly - people are bad measurers, they tend to cheat, round off, etc. Besides, we are cryptographers - have you ever seen one of us jump? Removed downvote, probably a joke :) –  owlstead Apr 23 at 11:21
Why to cheat here? And it is not hard to measure with enough precision. –  Dmitry Khovratovich Apr 23 at 11:33
You may not intentionally cheat, but just be compelled to round off to e.g. half centimeters. If you do a lot of measuring, you will notice that this is quite a strong tendency. Besides that, a long jump requires a lot of equipment to be in place, and 100 jumps are not healthy. Gosh, you were not joking. –  owlstead Apr 23 at 11:36
@owlstead Well, OP did not specify a time limit, so he could do, say, five jumps a day and be done in under two weeks. But yes, this kind of sampling is really not guaranteed to produce a uniform distribution. –  Thomas Apr 23 at 11:43
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