CDR: Re: any good idea?

[Jim Choate]

On Thu, 2 Nov 2000, Kenix wrote:

>     suppose we have two numbers, one is serial added(about 8~10 digits),
> another is a random number(about 7~12 digits), then how can i generate a 5
> digits number depends on both of them? there shouldn't have any key so i can
> verify the 5-digit number later just use the pervious two numbers, i know
> the security is completely depends on the method that how to generate this
> 5-digit number.
>     any good method you all can hint me? any good random number generator?

It's rather obvious, but:

ABmod(b^n)

Where A and B are your seeds/keys.

b is the number of elements in the alphabet.

n is the number of digits you want in the answer.

You could add a trusted hashing function in there as well,

(Hash(AB))mod(b^n)

Hope it helps.

As to random number generators, I'm fond of the radioactive and the
physicaly chaotic sort (they tend to be non-transportable and rather
large). Drip rate and magnetic pendulums being my favorite.

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