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Message
From: thilo<jeremias@o...>
Date: Wed Nov 30 11:59:32 CET 2005
Subject: [oc] Exponential
Steven R. McQueen wrote:>For positive integer exponents, and very large numbers, the BasicRSA
>project implements a square-and-multiply algorithm for modular
>exponentiation. It uses two copies of a shift-and-add multiplier, one to
>do modular squares, and one to do modular multiplication of dissimilar
>numbers. You have to do a square for every bit position in the exponent,
>and multiply the square by the result of the multiplication (hint, start
>with 1) every time the exponent bit position is 1.
>
>Testing can be a real pain, since you have to calculate all the
>exponents used in your test set and compare the correct results with
>whatever your core produces. I don't know a shortcut for that.
>
>
>
practical hint:
on unix is a tool called "bc"
This is really cool for long long big big numbers (integer/fixed point only)
:-)
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