SENG2250_Assignment3/Q2Tools.java

import java.math.BigInteger;

public class Q2Tools {

    Q2Tools()
    {
        //Nothing to do here
    }
    
    public void generateRSA()
    {

        int e = 65537;

        //Generate p

        //Generate q



    }

/**
 * Performs a fast modular exponation, (base^exponent)%modulus.
 * Takes input values as strings containg the numbers
 * @param base
 * @param exponent
 * @param modulus
 * @return
 */
    public BigInteger fme(String base, String exponent, String modulus)
    {
        BigInteger baseVal = new BigInteger(base);
        BigInteger exponentVal = new BigInteger(exponent);
        BigInteger modulusVal = new BigInteger(modulus);  
        
        if(modulusVal.equals(BigInteger.valueOf(1)))
        {  
            return BigInteger.valueOf(0);
        }

        BigInteger result = new BigInteger("1");

        while(exponentVal.compareTo(BigInteger.valueOf(0))==1)
        {   
            if(exponentVal.and(BigInteger.valueOf(1)).compareTo(BigInteger.valueOf(1))==0)
            {
               result = result.multiply(baseVal);
               result = result.mod(modulusVal);

            }

            exponentVal = exponentVal.shiftRight(1);
            baseVal = (baseVal.multiply(baseVal)).mod(modulusVal);
        }
        return result;
    }
}