Android Open Source - BerryTube Simple Crypto

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Back to project page BerryTube.
License

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

/*
 * BerryTubeChat android client//from   w  ww . j ava2  s .c  o m
 * Copyright (C) 2012-2013 Daniel Triendl <trellmor@trellmor.com>
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package com.trellmor.berrytubechat;

import java.security.GeneralSecurityException;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
 * Usage:
 * 
 * <pre>
 * String crypto = SimpleCrypto.encrypt(masterpassword, cleartext)
 * ...
 * String cleartext = SimpleCrypto.decrypt(masterpassword, crypto)
 * </pre>
 * 
 * @author ferenc.hechler
 */
public class SimpleCrypto {

  public static String encrypt(String key, String cleartext)
      throws GeneralSecurityException {
    byte[] rawKey = toByte(key);
    byte[] result = encrypt(rawKey, cleartext.getBytes());
    return toHex(result);
  }

  public static String decrypt(String key, String encrypted)
      throws GeneralSecurityException {
    byte[] rawKey = toByte(key);
    byte[] enc = toByte(encrypted);
    byte[] result = decrypt(rawKey, enc);
    return new String(result);
  }

  public static String generateKey() throws NoSuchAlgorithmException {
    final int outputKeyLength = 128; // 192 and 256 bits may not be
                      // available

    SecureRandom sr = new SecureRandom();
    KeyGenerator kg = KeyGenerator.getInstance("AES");
    kg.init(outputKeyLength, sr);
    SecretKey key = kg.generateKey();
    byte[] raw = key.getEncoded();
    return toHex(raw);
  }

  private static byte[] encrypt(byte[] raw, byte[] clear)
      throws GeneralSecurityException {
    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
    return cipher.doFinal(clear);
  }

  private static byte[] decrypt(byte[] raw, byte[] encrypted)
      throws GeneralSecurityException {
    SecretKeySpec skeySpec = new SecretKeySpec(raw, "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.DECRYPT_MODE, skeySpec);
    return cipher.doFinal(encrypted);
  }

  public static String toHex(String txt) {
    return toHex(txt.getBytes());
  }

  public static String fromHex(String hex) {
    return new String(toByte(hex));
  }

  public static byte[] toByte(String hexString) {
    int len = hexString.length() / 2;
    byte[] result = new byte[len];
    for (int i = 0; i < len; i++)
      result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
          16).byteValue();
    return result;
  }

  public static String toHex(byte[] buf) {
    if (buf == null)
      return "";
    StringBuffer result = new StringBuffer(2 * buf.length);
    for (int i = 0; i < buf.length; i++) {
      appendHex(result, buf[i]);
    }
    return result.toString();
  }

  private final static String HEX = "0123456789ABCDEF";

  private static void appendHex(StringBuffer sb, byte b) {
    sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
  }
}
Java Source Code List
