Java Encryption

From Null-pointer

Encrytion Example

/*
 * Created on 05-Apr-2006
 *
 * $Id: $
 * @author pkane
 */
package edu.london.ad;

import java.math.BigInteger;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

public class PasswordMaker
{
 private static byte[] desKeyData = "95179873".getBytes();
 
 private static byte[] encrypt(byte[] inpBytes, SecretKey key, String xform)
   throws Exception
 {
   Cipher cipher = Cipher.getInstance( xform );
   cipher.init( Cipher.ENCRYPT_MODE, key );
   return cipher.doFinal( inpBytes );
 }

 private static byte[] decrypt(byte[] inpBytes, SecretKey key, String xform)
   throws Exception
 {
   Cipher cipher = Cipher.getInstance( xform );
   cipher.init( Cipher.DECRYPT_MODE, key );
   return cipher.doFinal( inpBytes );
 }

 public static void main(String[] unused)
   throws Exception
 {
   String xform = "DES/ECB/PKCS5Padding";
   // Generate a secret key
   
   DESKeySpec desKeySpec = new DESKeySpec( desKeyData );
   SecretKeyFactory keyFactory = SecretKeyFactory.getInstance( "DES" );
   SecretKey secretKey = keyFactory.generateSecret( desKeySpec );
   
   String passwordToEncrypt = "myPassword";
   
   byte[] dataBytes = passwordToEncrypt.getBytes();
   
   byte[] encBytes = encrypt( dataBytes, secretKey, xform );
   
   BigInteger bi = new BigInteger( encBytes );

   byte[] decBytes = decrypt( encBytes, secretKey, xform );
   boolean expected = java.util.Arrays.equals( dataBytes, decBytes );
   
   System.out.println( "Password encrypted is [" + bi.toString( 36 ) + "]" );
   System.out.println( "Encryption check " + (expected ? "SUCCEEDED!" : "FAILED!") );

   String confirmEncryptionWord = "5kb1n582fpp9hple6nvn51jzg";
   BigInteger bigInteger = new BigInteger( confirmEncryptionWord, 36 );
   byte[] word = bigInteger.toByteArray();

   byte[] decrypt = decrypt( word, secretKey, xform );
   System.out.println( "decrypted [" + new String( decrypt ) + "]" );
  }
}

Hashing Example

private static String makePassword(String password)
     throws ControllerException
   {
       try
       {
           MessageDigest sha = MessageDigest.getInstance("SHA1");
           byte[] digest = sha.digest(password.getBytes());
           BigInteger testDigest = new BigInteger(1,digest);
           return testDigest.toString(36);
       }
       catch(Exception x)
       {
           throw new ControllerException( x );
       }
   }