// Lawrence Bush

// Lab Session:  1
// RCS account:  bushl


//	createkey.cpp -	This is the main file for the create key 
//			workspace.  The program accepts two prime 
//			numbers and computes a key (e), a decode key (d)
//			and the product (N) of the inputs.

#include <iostream>
#include <iomanip>



using std::endl;


#include "gcd.h"
#include "mmi.h"

int main(long int argc, char * argv[]) {
	

	
	
	// This function tests the size of argc to make sure two parameters were 
	// passed to the function.
	// Note that the computer considers the program name as one argument,
	// therefore, we test to see if there are 3 arguments.
	if(argc != 3)  {  // arg needs to be 3 for this
		std::cerr << "Invalid command line parameters.\n"
			<<	"\nUsage:  \ncreatekey.exe 5 11\n            [ p, q ]\n"
			<<"\n\nIf you are running this in VC++, do the following:\n     Alt+F7\n     Click on Debug Tab (next to general)"
			<<"\n     Type parameters "
			<<"into Program Arguments text box.\n"<<endl;
		
		
		exit(0);
	}
	// This function tests the arguments to make sure they are digits.
	for(int aaa=1;aaa<3;aaa++) {
		if (! isdigit(*(argv[aaa])) ) {
			std::cerr << "Invalid command line parameters.\nOne of your parameters is not a digit.\n"
			<<	"\nUsage:  \ncreatekey.exe 5 11\n            [ p, q ]"
			<<"\n\nIf you are running this in VC++, do the following:\n     Alt+F7\n     Click on Debug Tab (next to general)"
			<<"\n     Type parameters "
			<<"into Program Arguments text box.\n"<<endl;
			exit(0);
		}
	}
	
	// Get command-line agruments
	 long int p = atol(argv[1]);
	 long int q = atoi(argv[2]);

	
	//*********************************************

	std::cout<< "p = "<<p<<", q = "<<q<<endl; // regurgitate arguments

long int N = p*q; // calculate N
long int Nprime = (p-1) * (q-1); // calculate intermediate value for key
std::cout<<"N = " <<N<<endl; // output N
for(long int e=2;gcd(e,Nprime) != 1;e++); // find lowest gcd of e and Nprime
// Note:  this doesn't have to be the lowest, 
//        it can be any over 1,
//        but the way I wrote it, gives the lowest gcd over one.
std::cout<<"Public Key:  e = "<<e<<endl; // output e

long int d=mmi(e,Nprime);   // call mmi
if(d == -1) {
std::cout<<"Error finding Private Key!"<<endl;  
// If the mmi cannot create d, this error message occurs.
// This should not happen, however, because the gcd(e,Nprime)=1.
}


std::cout<<"Private Key: d = "<<d<<endl;  // and output d


// Overwrite with garbage to
// destroy any knowledge of these variables.
d=1234567;
p=1234567;
q=1234567;
Nprime=1234567;

return 0;

}