first.java

package first;
import java.security.MessageDigest;
import java.util.*;
import sun.misc.BASE64Encoder;
import java.io.IOException;

class StringXORer // TO EVALUATE THE XOR VALUE OF TWO GIVEN STRINGS
{ 
		public String xor(String st1,String st2)
		{
			String res="";
			int n=0;
			if(st1.length()>st2.length())
			{
				for(int i=st2.length();i<st1.length();i++)
					st2=st2+"0";
				n=st1.length();
			}
			else if(st1.length()<st2.length())
			{
				for(int i=st1.length();i<st2.length();i++)
				{
					st1=st1+"0";
				}
				n = st2.length();
			}
			else
				n=st1.length();
			for(int i=0;i<n;i++)
			{
					res=res+(char)(st2.charAt(i)^st1.charAt(i));
			}
			return res;
		}
}

class OneWayHash	// TO EVALUATE THE ONE-WAY-HASH VALUE OF A STRING USING "SHA-256"
{ 
    public String getStringFromSHA256(String example)
    {
        StringBuffer sb = new StringBuffer();
        byte byteData[];
        int l;
        try
        {
            MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
            messageDigest.update(example.getBytes());
            byteData = messageDigest.digest();
            l = byteData.length;
        }
        catch(Exception ex)
        {
            throw new RuntimeException(ex);
        }
        for (int i = 0; i < l; i++) 
        {
                sb.append(Integer.toString((byteData[i] & 0xff) + 0x100, 16).substring(1));
        }
        return sb.toString();
    }
}

public class First 
{
    public static void main(String[] args)// MAIN METHOD
    { 
    	Scanner sc = new Scanner(System.in);
    	System.out.println("Enter the ID :");
    	int ID = sc.nextInt();
    	System.out.println("Enter the PASSWORD :");
    	Scanner sc1 = new Scanner(System.in);
    	String PW = sc1.nextLine();
    	String ID_str = Integer.toString(ID);
    	System.out.println("Enter the BIOMETRIC data:");
    	Scanner sc2 = new Scanner(System.in);
        String bio = sc2.nextLine(); // RANDOM BIOMETRIC SEQUENCE
        StringXORer obj1 = new StringXORer();
        OneWayHash obj2 = new OneWayHash();
        int PSK = 8956;
        String PSK_str = Integer.toString(PSK);
        int port = 5241; // x value of the RC
        String port_str = Integer.toString(port);
        String Ai = obj2.getStringFromSHA256(ID_str + port_str);
        String Bi = obj2.getStringFromSHA256(Ai);
        String Ci = obj1.xor(obj2.getStringFromSHA256(obj1.xor(PW,bio)),Bi);
        String Di = obj1.xor(PSK_str,Ai);
        System.out.println("\nValues generated by the Registration Center(RC) on the smart card are : \n");
        System.out.println("ID : "+ID);
        System.out.println("Bi : "+Bi);
        System.out.println("Ci : "+Ci);
        System.out.println("Di : "+Di);
        
        System.out.println("\nEntering the login phase\n");
        Scanner sc3 = new Scanner(System.in);
        System.out.println("Enter the ID :");
    	int IDnew = sc3.nextInt();
    	System.out.println("Enter the PASSWORD :");
    	Scanner sc4 = new Scanner(System.in);
    	String PWnew = sc4.nextLine();
    	String ID_strNew = Integer.toString(ID);
    	System.out.println("Enter the BIOMETRIC data:");
    	Scanner sc5 = new Scanner(System.in);
        String bioNew = sc5.nextLine(); // RANDOM BIOMETRIC SEQUENCE
        String res = obj1.xor(obj2.getStringFromSHA256(obj1.xor(PWnew, bioNew)),Ci);
        if(res.equals(Bi))
        {
        	System.out.println("\nLOGIN SUCCESSFUL");
        	Random rand = new Random();
            int N = rand.nextInt(1000000) + 1000;
            String N1 = Integer.toString(N);
            System.out.println("N1 : "+N1);
            String M1 = obj1.xor(obj2.getStringFromSHA256(Bi),N1);
            System.out.println("M1 : "+M1);
            String AID = obj1.xor(obj2.getStringFromSHA256(N1),ID_strNew);
            System.out.println("AID : "+AID);
            String M2 = obj2.getStringFromSHA256(N1 + AID + Di);
            System.out.println("\nMessage generated for authentication : ");
            System.out.println("M2 : "+M2);
        }
        else
        {
        	System.out.println("\nLOGIN FAILED");
        	return;
        }
        
    }
}