AES 128Bit encryption between Java and PHP

Here is how AES encryption works between Java and PHP using the mcrypt module in PHP.

This is mainly a quick summary of the 4-part tutorial at: http://propaso.com/blog/?cat=6

Generate Key in Java

String iv = "fedcba9876543210";
IvParameterSpec ivspec;
KeyGenerator keygen;
Key key;

ivspec = new IvParameterSpec(iv.getBytes());

keygen = KeyGenerator.getInstance("AES");
keygen.init(128);
key = keygen.generateKey();

keyspec = new SecretKeySpec(key.getEncoded(), "AES");

Encryption in Java

Cipher cipher;
byte[] encrypted;

cipher = Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(Cipher.ENCRYPT_MODE, keyspec, ivspec);
encrypted = cipher.doFinal(padString(text).getBytes());

Decryption in Java

Cipher cipher;
byte[] decrypted;

cipher = Cipher.getInstance("AES/CBC/NoPadding");
cipher.init(Cipher.DECRYPT_MODE, keyspec, ivspec);
decrypted = cipher.doFinal(hexToBytes(code));

Encryption in PHP

function encrypt($str, $key) {
  $key = $this->hex2bin($key);    

  $td = mcrypt_module_open("rijndael-128", "", "cbc", "fedcba9876543210");

  mcrypt_generic_init($td, $key, CIPHER_IV);
  $encrypted = mcrypt_generic($td, $str);

  mcrypt_generic_deinit($td);
  mcrypt_module_close($td);

  return bin2hex($encrypted);
}

Decryption in PHP

function decrypt($code, $key) {
  $key = $this->hex2bin($key);
  $code = $this->hex2bin($code);

  $td = mcrypt_module_open("rijndael-128", "", "cbc", "fedcba9876543210");

  mcrypt_generic_init($td, $key, CIPHER_IV);
  $decrypted = mdecrypt_generic($td, $code);

  mcrypt_generic_deinit($td);
  mcrypt_module_close($td);

  return utf8_encode(trim($decrypted));
}

Additional functions in Java

private byte[] hexToBytes(String hex) {
  String HEXINDEX = "0123456789abcdef";
  int l = hex.length() / 2;
  byte data[] = new byte[l];
  int j = 0;

  for (int i = 0; i < l; i++) {
    char c = hex.charAt(j++);
    int n, b;

    n = HEXINDEX.indexOf(c);
    b = (n & 0xf) << 4;
    c = hex.charAt(j++);
    n = HEXINDEX.indexOf(c);
    b += (n & 0xf);
    data[i] = (byte) b;
  }

  return data;
}

private String padString(String source) {
  char paddingChar = ' ';
  int size = 16;
  int padLength = size - source.length() % size;

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

  return source;
}

Additional functions in PHP

function hex2bin($hexdata) {
  $bindata = "";

  for ($i = 0; $i < strlen($hexdata); $i += 2) {
    $bindata .= chr(hexdec(substr($hexdata, $i, 2)));
  }

  return $bindata;
}