//Deffie
package rsa;
import java.math.*;
import java.util.*;

class DHM{
    private static long power(long a, long b, long p)
    {
        if (b == 1)
            return a;
        else
            return (((long)Math.pow(a, b)) % p);
    }
    DHM()
    {
        long P, G, x, a, y, b, ka, kb;
        P = 23;
        System.out.println("The value of P:" + P);

        G = 9;
        System.out.println("The value of G:" + G);
        a = 4;
        System.out.println("The private key a for A  :" + a);
        x = power(G, a, P);
        
        b = 3;
        System.out.println("The private key X for party B :" + b);
        
        y = power(G, b, P);
        ka = power(y, a, P); 
        kb = power(x, b, P);
        
        System.out.println("Secret key for the party A is:" + ka);
        System.out.println("Secret key for the party B is:" + kb);
      }
    }

    public class rsaprg
    {
        public static void main(String[] args) {
            DHM cObj= new DHM();
        }
    }
    
    
    

// RSA week 9 program
import java.math.*;
import java.util.*;

class RSA {
    RSA()
    { Scanner sc=new Scanner(System.in);
        int p, q, n, z, d = 0, e, i;

        // The number to be encrypted and decrypted
        int msg ;
        System.out.println(" enter a message as a number from :1-100");
        msg=sc.nextInt();
        double c;
        BigInteger msgback;

        // 1st prime number p
        p = 17;

        // 2nd prime number q
        q = 11;
        n = p * q;
        z = (p - 1) * (q - 1);
        System.out.println("the value of z = " + z);

        for (e = 2; e < z; e++) {

            // e is for public key exponent
            if (gcd(e, z) == 1) {
                break;
            }
        }
        System.out.println("the value of e = " + e);
        for (i = 0; i <= z; i++) {
            
            int x = 1 + (i * z);

            // d is for private key exponent
            if (x % e == 0) {
                d = x / e;
                break;
            }
        }
        System.out.println("the value of d = " + d);
        c = (Math.pow(msg, e)) % n;
        System.out.println("the input message is : " + msg);
    System.out.println("Encrypted message is : " + c);

        // converting int value of n to BigInteger
        BigInteger N = BigInteger.valueOf(n);

        // converting float value of c to BigInteger
        BigInteger C = BigDecimal.valueOf(c).toBigInteger();
        msgback = (C.pow(d)).mod(N);
        System.out.println("Decrypted message is : "
                        + msgback);
    }

    static int gcd(int e, int z)
    {
        if (e == 0)
            return z;
        else
            return gcd(z % e, e);
    }
}

public class Main
{
    public static void main(String[] args) {
        //System.out.println("Hello World");
        RSA rObje=new RSA();
    }
}



//SHA512

package abc.java;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Scanner;

 class SHA512 {
    public static String encryptThisString(String input)
    {
        try {
            MessageDigest md = MessageDigest.getInstance("SHA-512");

            byte[] messageDigest = md.digest(input.getBytes());

            BigInteger no = new BigInteger(1, messageDigest);

            String hashtext = no.toString(16);

            while (hashtext.length() < 32) {
                hashtext = "0" + hashtext;
            }

            return hashtext;
        }
        catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }
    SHA512() 
    {
        Scanner sc=new Scanner(System.in);
        System.out.println(" enter text of your choice ");
        String s=sc.nextLine();
        System.out.println("HashCode Generated by SHA-512 for: ");

        String s1 = "Cryptography Lab";
        System.out.println("\n" + s + " : " + encryptThisString(s1));
    }
}
class Main
{ public static void main(String args[])

  { SHA512 obj=new SHA512();
  }
    
}


//Elliptic Curve

import java.util.Scanner; 
public class EllipticCurve {
    public static void main(String arg[])
    {
     float x1,y1,x2,y2,x3,y3,m,a,b;
     Scanner sc= new Scanner(System.in);
     System.out.println(" enter thee coordiantee of two points");
             x1=sc.nextFloat();
             y1=sc.nextFloat();
             x2=sc.nextFloat();
             y2=sc.nextFloat(); 
             a=sc.nextFloat();
        if(x1!=x2)
        { m=(y1-y2)/(x1-x2);
        
             x3=m*m-x1-x2;
             y3=-y1+m*(x1-x3);
             System.out.print(x3+"  "+y3);
        }
        else if(y1==-y2)
        {System.out.println(" identity");
        }
        else if(x1==y1 && y1==y2)       
        {System.out.println(" c==b or c==a");
        }
        else
        {
            m=(3*x1*x1+a)/(2*y1);
            x3=m*m- 2 * x1;
            y3= -y1+m*(x1-x3); 
            System.out.print(x3+"  "+y3);
        }
    }
             
}








    // DES
    
    import java.util.*;
class keygen{
 public static void main(String args[]){
    int i;
   Scanner sc=new Scanner(System.in);
    int key[]=new int[10];
  System.out.println("enteer key number :");
   for(i=0;i<key.length;i++){
    key[i]=sc.nextInt();
    }
    int p10[]=new int[10];
      p10[0]=key[2];
        p10[1]=key[4];
       p10[2]=key[1];
        p10[3]=key[6];
        p10[4]=key[3];
         p10[5]=key[9];
         p10[6]=key[0];
         p10[7]=key[8];
          p10[8]=key[7];
           p10[9]=key[5];
           System.out.println("p10 is ");
      for(int k=0;k<key.length;k++)
        System.out.print(""+p10[k]);
        int L11[]=new int[5];
        L11[0]=p10[1];
        L11[1]=p10[2];
        L11[2]=p10[3];
        L11[3]=p10[4];
        L11[4]=p10[0];
         System.out.println("\n    ");
        int L12[]=new int[5];
        L12[0]=p10[6];
        L12[1]=p10[7];
        L12[2]=p10[8];
        L12[3]=p10[9];
        L12[4]=p10[5];
         
        System.out.println("L11=");
        for(int j=0;j<L11.length;j++){
            System.out.print(""+L11[j]);
           
        }
          System.out.println("\n L12=");
           for(int j=0;j<L12.length;j++){
           System.out.print(""+L12[j]);
           
        } 
            System.out.println("\n ");
            
            int p81[]=new int[8];
            p81[0]=L12[0];
            p81[1]=L11[2];
            p81[2]=L12[2];
            p81[3]=L11[3];
            p81[4]=L12[2];
            p81[5]=L11[4];
            p81[6]=L12[4];
            p81[7]=L12[3];
  System.out.println("the firstkey is ");
        for(int j=0;j<p81.length;j++){
            System.out.print(""+p81[j]);
        }
          System.out.println("\n ");
        int L21[]=new int[5];
        L21[0]=L11[2];
         L21[1]=L11[3];
          L21[2]=L11[4];
           L21[3]=L11[0];
            L21[4]=L11[1];
            int L22[]=new int[5];
            L22[0]=L12[2];
            L22[1]=L12[3];
            L22[2]=L12[4];
            L22[3]=L12[0];
            L22[4]=L12[1];
            System.out.print("\n L21==");
            for(int j=0;j<L21.length;j++){
                System.out.print(L21[j]);
            }
            System.out.println("\n ");
             System.out.println("L22==");
              for(int j=0;j<L22.length;j++){
                System.out.print(L22[j]);
            }
            int p82[]=new int[8];
            p82[0]=L22[0];
            p82[1]=L21[2];
            p82[2]=L22[2];
            p82[3]=L21[3];
            p82[4]=L22[2];
            p82[5]=L21[4];
            p82[6]=L22[4];
            p82[7]=L22[3];
            System.out.println(" \n   ");
            System.out.println("\n the second key is  P82==");
      for(int j=0;j<p82.length;j++){
          System.out.print(""+p82[j]);
      }
}}















//AES

import javax.crypto.Cipher;  
import javax.crypto.SecretKey;  
import javax.crypto.SecretKeyFactory;  
import javax.crypto.spec.IvParameterSpec;  
import javax.crypto.spec.PBEKeySpec;  
import javax.crypto.spec.SecretKeySpec;  
import java.nio.charset.StandardCharsets;  
import java.security.InvalidAlgorithmParameterException;  
import java.security.InvalidKeyException;  
import java.security.NoSuchAlgorithmException;  
import java.security.spec.InvalidKeySpecException;  
import java.security.spec.KeySpec;  
import java.util.Base64;  
import javax.crypto.BadPaddingException;  
import javax.crypto.IllegalBlockSizeException;  
import javax.crypto.NoSuchPaddingException;  
class AES  
{  
    /* Private variable declaration */  
    private static final String SECRET_KEY = "123456789";  
    private static final String SALTVALUE = "abcdefg";  
   
    /* Encryption Method */  
    public static String encrypt(String strToEncrypt)   
    {  
    try   
    {  
      /* Declare a byte array. */  
      byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};  
      IvParameterSpec ivspec = new IvParameterSpec(iv);        
      /* Create factory for secret keys. */  
      SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");  
      /* PBEKeySpec class implements KeySpec interface. */  
      KeySpec spec = new PBEKeySpec(SECRET_KEY.toCharArray(), SALTVALUE.getBytes(), 65536, 256);  
      SecretKey tmp = factory.generateSecret(spec);  
      SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");  
      Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");  
      cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivspec);  
      /* Retruns encrypted value. */  
      return Base64.getEncoder()  
.encodeToString(cipher.doFinal(strToEncrypt.getBytes(StandardCharsets.UTF_8)));  
    }   
    catch (InvalidAlgorithmParameterException | InvalidKeyException | NoSuchAlgorithmException | InvalidKeySpecException | BadPaddingException | IllegalBlockSizeException | NoSuchPaddingException e)   
    {  
      System.out.println("Error occured during encryption: " + e.toString());  
    }  
    return null;  
    }  
    
    /* Decryption Method */  
    public static String decrypt(String strToDecrypt)   
    {  
    try   
    {  
      /* Declare a byte array. */  
      byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};  
      IvParameterSpec ivspec = new IvParameterSpec(iv);  
      /* Create factory for secret keys. */  
      SecretKeyFactory factory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");  
      /* PBEKeySpec class implements KeySpec interface. */  
      KeySpec spec = new PBEKeySpec(SECRET_KEY.toCharArray(), SALTVALUE.getBytes(), 65536, 256);  
      SecretKey tmp = factory.generateSecret(spec);  
      SecretKeySpec secretKey = new SecretKeySpec(tmp.getEncoded(), "AES");  
      Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");  
      cipher.init(Cipher.DECRYPT_MODE, secretKey, ivspec);  
      /* Retruns decrypted value. */  
      return new String(cipher.doFinal(Base64.getDecoder().decode(strToDecrypt)));  
    }   
    catch (InvalidAlgorithmParameterException | InvalidKeyException | NoSuchAlgorithmException | InvalidKeySpecException | BadPaddingException | IllegalBlockSizeException | NoSuchPaddingException e)   
    {  
      System.out.println("Error occured during decryption: " + e.toString());  
    }  
    return null;  
    }  
     
    AES()  
    {  
        /* Message to be encrypted. */  
        String originalval = "AES Encryption";  
        /* Call the encrypt() method and store result of encryption. */  
        String encryptedval = encrypt(originalval);  
        /* Call the decrypt() method and store result of decryption. */  
        String decryptedval = decrypt(encryptedval);  
        /* Display the original message, encrypted message and decrypted message on the console. */  
        System.out.println("Original value: " + originalval);  
        System.out.println("Encrypted value: " + encryptedval);  
        System.out.println("Decrypted value: " + decryptedval);  
    }  
} 
class Main{
    
     public static void main(String[] args)  
     {
        AES obj= new AES();
     }
}