Timothy Murphy said the following on 03/01/2014 14:20: > Is this a meaningful statement? How do you measure the "entropy" of a seed > (which I take to be a string)? And if you can, is it true that you can > decrypt a string with low entropy? The mathematic behind a PRNG (or DRNG to use NIST terminolgy) + Elliptic Curve falls beyond my comprehension, so I have to take for granted what experts say. The link to PDF I qoted in my previous message goes deep in detail, you can refer to that paper if you need more informations. > Nb What you say may be perfectly valid, I'd just like to know exactly what > it means, if indeed it has a mathematical meaning. In essence it means that if an algorythm that builds its foundations on the fact that each new number of a sequence is not predictable, when that sequence generates predictable numbers, the algorythm fails. There are some models that define or analyze if a sequence is "randomic" you can google around or take a look at http://www.issihosts.com/haveged/ais31.html Mind that you can end up with a big headache :) Ciao, luigi -- / +--[Luigi Rosa]-- \ Men occasionally stumble over the truth, but most of them pick themselves up and hurry off as if nothing had happened. --Winston Churchill