Android Open Source - ImproveMyCity-Mobile My_ Crypt_ Utils

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License

The source code is released under:
GNU General Public License
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Java Source Code

// My_Crypt_Utils 
package com.mk4droid.IMC_Utils;
//from   w ww. j  a va2  s . c om
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

import android.util.Log;

import com.mk4droid.IMC_Store.Constants_API;

/**
 * Cryptography utility. Encrypt a string (the Password typed by the user) using 
 *         algorithm AES/CBC/PKCS5Padding and the Constants.EncKey. 
 *         
 * If typed password is less than 16 chars then it is padded with ' '.
 * Output is a array of bytes.         
 * 
 * @copyright   Copyright (C) 2012 - 2013 Information Technology Institute ITI-CERTH. All rights reserved.
 * @license     GNU Affero General Public License version 3 or later; see LICENSE.txt
 * @author      Dimitrios Ververidis for the Multimedia Group (http://mklab.iti.gr). 
 */
public class My_Crypt_Utils {
        private IvParameterSpec ivspec;
        private SecretKeySpec keyspec;
        private Cipher cipher;
        private String SecretKey = Constants_API.EncKey;
        private String iv = SecretKey;
        
        String TAG_Class =  getClass().getName();
        
        /** Initialize cipher AES CBC using Constants.EncKey */
        public My_Crypt_Utils(){
          ivspec  = new IvParameterSpec(iv.getBytes());
          keyspec = new SecretKeySpec(SecretKey.getBytes(), "AES");
          
          try {
            cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
          } catch (NoSuchAlgorithmException e) {
            Log.e(Constants_API.TAG, TAG_Class + " " + e.getMessage() );
          } catch (NoSuchPaddingException e) {
            Log.e(Constants_API.TAG, TAG_Class + " " + e.getMessage() );
          }
        }
        
        //================= encrypt ================
        /**
         * Encrypt a string using Constants.EncKey
         * 
         * @param text
         * @return
         * @throws Exception
         */
        public byte[] encrypt(String text) throws Exception {
          if(text == null || text.length() == 0)
            throw new Exception("Empty string");

          byte[] encrypted = null;

          try {
            cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
            
            byte[] gb = padString(text).getBytes();
            
            encrypted = cipher.doFinal(gb);
          } catch (Exception e){                       
            throw new Exception("[encrypt] " + e.getMessage());
          }
          return encrypted;
        }

        //============ padString ============================
        /** Add empty char ' ' so that output has a length of 16 chars */
        private static String padString(String source){
          
          char paddingChar = ' ';
          int size = 16;
          int x = source.length() % size;
          int padLength = size - x;

          for (int i = 0; i < padLength; i++)
            source += paddingChar;
          
          return source;
        }
}

//-------------------- FOR FUTURE USE -------------------------------------

///** Decrypt a string using Constants.EncKey
// * 
// * @param code
// * @return
// * @throws Exception
// */
//public byte[] decrypt(String code) throws Exception
//{
//  if(code == null || code.length() == 0)
//    throw new Exception("Empty string");
//
//  byte[] decrypted = null;
//
//  try {
//    cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
//
//    decrypted = cipher.doFinal(hexToBytes(code));
//  } catch (Exception e)
//  {
//    throw new Exception("[decrypt] " + e.getMessage());
//  }
//  return decrypted;
//}
//
//
//
//
//
//        
//public static byte[] hexToBytes(String str) {
//  if (str==null) 
//    return null;
//  else if (str.length() < 2) 
//    return null;
//  else {
//    int len = str.length() / 2;
//    byte[] buffer = new byte[len];
//    for (int i=0; i<len; i++) 
//      buffer[i] = (byte) Integer.parseInt(str.substring(i*2,i*2+2),16);
//
//    return buffer;
//  }
//}
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