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Friday, October 20, 2006

10097 32533 the sequel: 76520 13586!

I decided to post this one as a puzzle to see whether anyone would work it out. Ed did so pretty promptly.

So, for everyone else. 10097 32533 76520 13586 are the first twenty digits of Rand's classic A Million Random Digits with 100,000 Normal Deviates.

Twenty years ago I read a novel (called "The Consultant", I think) which detailed the tracking down of a criminal who was using a bank's internal communication network to deliver a program which stole money to a computer which was able to process the fraudulent transactions. The program was known to be delivered encrypted and the security analyst was having serious trouble decrypting it. Someone else who, coincidentally, had been idly perusing a book of random numbers (possibly Rand's) looked at the block of digits representing the "encrypted" program and immediately recognised it as a page of the book of random numbers, which of course put the analyst back on track; seeking a copy of the actual encrypted program to work on rather than wasting time trying to decrypt the block of random numbers that was being used as cover between thefts.

The idea of a published group of actually random numbers struck a chord with me. I never pursued it, but spotting Schneier's post last week brought this memory back. Naturally, posting an open description and link would not have been in the spirit of the book, so I merely posted the opening digits. I'm guessing Ed used Google rather than recognising them on sight, but we'll never know for certain.

Oh, and kudos to Rand for freely the publishing the digits in machine-readable form too.

UPDATE 20-Oct-2006: While searching for some of the links above, I also discovered a source of allegedly random data from fourmilab. (I say "allegedly" because if you're going to depend upon it, you need to trust not only that they are getting the data from where they say they are getting it, and that it is a truly random process (this seems certain), but that the path between it and you has not been compromised.)