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Comment by xorglorb | Hacker News Reader

> U.S. law requires that Diversity Immigrant visas be made available through a strictly random process. A computer programming error resulted in a selection that was not truly random.

Computer generated numbers are never truly random. At what point is it "random enough"?

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Many computers have physical entropy sources, so they can create truly random numbers. http://www.cryptography.com/public/pdf/IntelRNG.pdf

I don't think it's really necessary to use true quantum randomness. A good-enough-for-government-work definition of a random drawing is that every applicant has an equal chance (to N decimal places) of being chosen at the time they submit their application.

For this, pseudorandom is good enough. Sure, it's completely deterministic which applications will get chosen once you've chosen your algorithm and seed. But how do you choose your seed? Probably from the clock at the time you run the program. And what determines the precise time you run the program? Why, a bunch of neural signals going around in the head of the dude whose job it is to press "enter" on the greencard lottery program.

There are some purposes for which random is better than pseudorandom, this ain't one of 'em.

I can't find anything in a quick search, but I recall seeing a report ~15 years ago on what was considered sufficiently random for lotteries. It was kind of tiered, most low-level stuff was based on pseudo with a seed based on dice throw (i.e. they rolled something like 10d10 under specific conditions, then used that as seed) with some higher up stuff being die or ball pick. This was before having entropy generators (like an over level amp hooked to a A/D) being commonplace. Not sure what they like now, but I'm sure political/legal argued about it, yelled at each other and eventually settled on what was "random enough" fairly arbitrarily but sufficiently enough that no one complains. There's probably enough stuff around that needs to be "legally random" to have laws about it though.

For those interested, here's a nice intro that offers some insight into that question.

http://www.johndcook.com/Beautiful_Testing_ch10.pdf

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