> Why make that assumption? Well, this is a slippery slope. We're already assuming the spy has a lot of information, and the ability to get more, and that I'm generating random numbers frequently enough to make it worth his while to continue spying (he's already been spying for a couple months now, in order to get his 100 samples of 1000 numbers each). We also have to assume he knows how I'm using these numbers (or, more specifically, when I'm using a number in an application that interests him, e.g. cryptography as opposed to playing with a J verb).
If we assume he also knows that I'm using GB_FLIP, then why not assume he also has access to my initial seed and be done with it? > Let us first tackle the easy case where we know > that it was generated by GB_FLIP. But sure, in the interest of learning how this stuff works, let's assume he can sample as you described earlier, and also knows I'm using the GB_FLIP algorithm. How would he go about predicting future generated numbers? One easy way I can come up with is dispense with the sampling, and just wait until I've generated <:2^55 numbers (which he knows is GB_FLIP's period). Then he'd be able to predict the entire future stream. Of course, he'd have to wait many months or years before that happened, depending on my appetite for random numbers. -Dan ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
