php写的AES加密解密类分享

今天写了一个php的aes加密类。适用于yii的扩展。
如果不用在yii框架中，把代码中yii::app()->params['encryptkey'] 换成你对应的默认key就可以了。
类代码:

<?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。
 * 同时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);
	}
}