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/**
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document.write(' * FastExpon is a fast computational algorithm for computing large exponents. x^e % m
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document.write(' * This algorithm was used for a cryptography course dealing with RSA.
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document.write(' * Feel free to slice it up for yourself. :)
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document.write(' * @author Alan Lambkin
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document.write(' * @version 1.0 September 2006
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document.write(' */');
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public class FastExpon
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{');
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public long y =
1;
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');
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/**
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document.write(' * Performs the calculation...
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document.write(' * While the exponent is not zero:
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document.write(' * If the exponent is even, square the base, mod m, and divide the exponent by 2.
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document.write(' * If the exponent is odd, mulitply the base times y (initially set to 1) mod m,
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document.write(' * now place that value into y, and subtract 1 from the exponent.
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document.write(' * @parm x the base
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document.write(' * @parm e the exponent
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document.write(' * @parm m the mod
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document.write(' * @return The answer, x raised to e, mod m.
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document.write(' */');
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public long fex
(long x,
long e,
long m
)');
document.write('
{');
document.write('
while (e !=
0)');
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{');
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if (e%
2==
0)');
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{');
document.write(' x=x*x%m;
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document.write(' e=e/
2;
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document.write('
}');
document.write('
else');
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{');
document.write(' y=x*y%m;
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document.write(' e=e
-1;
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document.write('
}');
document.write('
}');
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return y;
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}');
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document.write('
/**
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document.write(' * Just a simple main program so I can test before posting.
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document.write(' * Prints out the answer.
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document.write(' */');
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public static void main
(String[] args
)');
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{');
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long x =
6916502;
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long e =
2773637;
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long m =
8326363;
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document.write(' FastExpon f =
new FastExpon
();
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document.write('
System.
out.
println(x +
" raised to the " + e +
" power, mod " + m +
" = " + f.
fex(x,e,m
));
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document.write('
}');
document.write('
}');
document.write('