Whilst the coprimality of parameters ensure uniqueness whilst saving you from have to track previous picks; the method has a weakness: if an attacker can cause you to give him two consecutive picks -- say, by inspecting the latest additions to the parts inventory -- he can determine S, and from that start guessing your new part numbers.

He doesn't even have to find to consecutive picks; only two that where allocated close to each other. If the difference between them is prime, he's probably found S; if not, he only need find the prime factors of that difference to find it.

With a little more inspection and analysis, he will be able to determine your offset; and at that point, the benefits of allocating "seemingly random" part numbers is defeated.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority". I knew I was on the right track :)
In the absence of evidence, opinion is indistinguishable from prejudice.

In reply to Re^2: Check randomly generated numbers have not been used before by BrowserUk
in thread Check randomly generated numbers have not been used before by R3search3R

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