rsa_1.txt

#include<iostream>
#include<math.h>
using namespace std;

int gcd(int a,int b)
{
	int r;
    while(1)
	{
		r = b%a;
		if (r == 0)
			return a;
		b = a;
		a = r;
    }
}
int main()
{
	int p,q,n,z,d=0,e,i,x,y;
	double msg,c,msgback;
	cout<<"Enter the number to be encrypted :";
	cin>>msg;
	cout<<"Enter first prime number :";
	cin>>p;
	cout<<"Enter second prime number :";
	cin>>q;
	n=p*q;
	z=(p-1)*(q-1);
	
	cout<<"The value of Z is :" << z <<endl;
	for(e=2;e<z;e++)
	{
		if (gcd(e,z)==1)
		{
			break;
		}
	}
	cout<<"The value of E is :" << e <<endl;
	i=1;
	while(1)
	{
		int x=1+(i*z);
		if(x%e==0)      
		{
		d=x/e;
		break;
		}
		i++;
	}
	cout<<"The value of D is :" << d <<endl;
	c=pow(msg,e);
	c=fmod(c,n);
	cout<<"Encrypted Message is :" << c << endl;
	msgback = pow(c,d);
	msgback=fmod(msgback,n);
	cout<<"Decrypted Message is :" << msgback << endl;
	return 0;
}

==========OUTPUT===========
Enter the number to be encrypted :7 
Enter first prime number :11
Enter second prime number :3
The value of Z is :20
The value of E is :3
The value of D is :7
Encrypted Message is :13
Decrypted Message is :7