Algorithms

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//		g++ main.c -o main<br />
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#include <stdio.h><br />
#include <stdlib.h><br />
#include "math.h"<br />
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int do_crypto(int M, int e, int N);<br />
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int main()<br />
{<br />
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	printf("...\n");<br />
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	//	TWO PRIMES FOR OUR KEY<br />
	int p = 17;<br />
	int q = 11;<br />
	//	THIRD PART OF OUR KEY (PUBLIC)<br />
	int e = 7;<br />
	//	CALCULATE THE OTHER PART OF THE PUBLIC KEY<br />
	int N = p * q;	//	= 187<br />
	<br />
	//	THE CHARACTER TO ENCODE AS ASCII<br />
	int M = 88;<br />
	//int M = "M";<br />
	<br />
	//	ENCRYPT A CHARACTER<br />
	//int C = int ( M * exp(e) ) % N;<br />
	int C = do_crypto(M, e, N);		//	int M, int e, int N)<br />
	printf("C = %d \n", C);<br />
	<br />
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	//	CALCULATE THE DECRYPT KEY<br />
	//int d = ( 1 % ( (p-1) * (q-1) ) ) / e;<br />
	int d =  ( ( (p-1) * (q-1) ) / e );<br />
	printf("d = %d \n", d);<br />
	<br />
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	// DECRYPT THE CHARACTER<br />
	int m = do_crypto(11, 23, 187);		//	int C, int d, int N)<br />
	printf("m = %d \n", m);<br />
	<br />
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	return 0;<br />
}<br />
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int do_crypto(int M, int e, int N)<br />
{<br />
	int iret = int ( M * exp(e) ) % N;<br />
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	return iret;<br />
}<br />
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