From: J.A. Terranson Interesting thread going on at [1]dsfjdssdfsd@ietf.org. Forwarded for our collective interest and amusement. ---------- Forwarded message ---------- Date: Thu, 23 Jan 2014 23:38:07 +0100 From: Krisztin Pintr <[2]pinterkr@gmail.com> To: Michael Hammer <[3]michael.hammer@yaanatech.com> Cc: "[4]dsfjdssdfsd@ietf.org" <[5]dsfjdssdfsd@ietf.org>, "[6]ietf@hosed.org" <[7]ietf@hosed.org> Subject: Re: [dsfjdssdfsd] Any plans for drafts or discussions on here? Michael Hammer (at Thursday, January 23, 2014, 9:49:32 PM): >> This may get off-topic, but are there good software tools for testing >> entropy, >> that could help applications determine if the underlying system is giving >> them good input? >disclaimer: i'm no expert, it is just what i gathered. (i'm pretty >much interested in randomness.) >short answer: no >long answer: in some situations yes. if you are handed a bunch of >data, all you can do is to try different techniques to put an upper >limit on the entropy. for example you can calculate the shannon >entropy assuming independent bits. then you can hypothesize some >interdependence, and see if you can compress the data. you can apply >different lossless compression methods. the better compression you >find puts an upper limit on the entropy. but never a lower limit. Consider this: Suppose I handed you the digits of pi, the digits from the millionth digit to the two-millionth digit, and I asked you to determine if they are 'random'. By many tests, you'd conclude that they are random. (Or, at least 'normal' [8] http://en.wikipedia.org/wiki/Normal_numbers ) But, in reality they are highly non-random, precisely because they are a million sequential digits of pi. But you wouldn't know that, if you didn't know that. Jim Bell References 1. mailto:dsfjdssdfsd@ietf.org. 2. mailto:pinterkr@gmail.com 3. mailto:michael.hammer@yaanatech.com 4. mailto:dsfjdssdfsd@ietf.org 5. mailto:dsfjdssdfsd@ietf.org 6. mailto:ietf@hosed.org 7. mailto:ietf@hosed.org 8. http:///