php写的AES加密解密类分享

<?php
/
  php AES加解密类
  如果要与java共用，则密钥长度应该为16位长度
  因为java只支持128位加密，所以php也用128位加密，可以与java互转。
  AES的标准也是128位。只是RIJNDAEL算法可以支持128，192和256位加密。
  java 要使用AES/CBC/NoPadding标准来加解密
  
  @author Terry
 
 /
class PhpAes
{
	/
	  This was AES-128 / CBC / NoPadding encrypted.
	  return base64_encode string
	  @author Terry
	  @param string $plaintext
	  @param string $key
	 /
	public static function AesEncrypt($plaintext,$key = null)
	{
		$plaintext = trim($plaintext);
		if ($plaintext == '') return '';
		if(!extension_loaded('mcrypt'))
			throw new CException(Yii::t('yii','AesEncrypt requires PHP mcrypt extension to be loaded in order to use data encryption feature.'));
		$size = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
		$module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');
		$key=self::substr($key===null ? Yii::app()->params['encryptKey'] : $key, 0, mcrypt_enc_get_key_size($module));
		/ Create the IV and determine the keysize length, use MCRYPT_RAND
		  on Windows instead /
		$iv = substr(md5($key),0,mcrypt_enc_get_iv_size($module));
		/ Intialize encryption /
		mcrypt_generic_init($module, $key, $iv);

		/ Encrypt data /
		$encrypted = mcrypt_generic($module, $plaintext);

		/ Terminate encryption handler /
		mcrypt_generic_deinit($module);
		mcrypt_module_close($module);
		return base64_encode($encrypted);
	}

	/
	  This was AES-128 / CBC / NoPadding decrypted.
	  @author Terry
	  @param string $encrypted		base64_encode encrypted string
	  @param string $key
	  @throws CException
	  @return string
	 /
	public static function AesDecrypt($encrypted, $key = null)
	{
		if ($encrypted == '') return '';
		if(!extension_loaded('mcrypt'))
			throw new CException(Yii::t('yii','AesDecrypt requires PHP mcrypt extension to be loaded in order to use data encryption feature.'));

		$ciphertext_dec = base64_decode($encrypted);
		$module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');
		$key=self::substr($key===null ? Yii::app()->params['encryptKey'] : $key, 0, mcrypt_enc_get_key_size($module));

		$iv = substr(md5($key),0,mcrypt_enc_get_iv_size($module));

		/ Initialize encryption module for decryption /
		mcrypt_generic_init($module, $key, $iv);

		/ Decrypt encrypted string /
		$decrypted = mdecrypt_generic($module, $ciphertext_dec);

		/ Terminate decryption handle and close module /
		mcrypt_generic_deinit($module);
		mcrypt_module_close($module);
		return rtrim($decrypted,"\0");
	}

	/
	  Returns the length of the given string.
	  If available uses the multibyte string function mb_strlen.
	  @param string $string the string being measured for length
	  @return integer the length of the string
	 /
	private static function strlen($string)
	{
		return extension_loaded('mbstring') ? mb_strlen($string,'8bit') : strlen($string);
	}

	/
	  Returns the portion of string specified by the start and length parameters.
	  If available uses the multibyte string function mb_substr
	  @param string $string the input string. Must be one character or longer.
	  @param integer $start the starting position
	  @param integer $length the desired portion length
	  @return string the extracted part of string, or FALSE on failure or an empty string.
	 /
	private static function substr($string,$start,$length)
	{
		return extension_loaded('mbstring') ? mb_substr($string,$start,$length,'8bit') : substr($string,$start,$length);
	}
}