php对称加密

/**
 * 常用对称加密算法类
 * 支持密钥：64/128/256 bit（字节长度8/16/32）
 * 支持算法：DES/AES（根据密钥长度自动匹配使用：DES:64bit AES:128/256bit）
 * 支持模式：CBC/ECB/OFB/CFB
 * 密文编码：base64字符串/十六进制字符串/二进制字符串流
 * 填充方式: PKCS5Padding（DES）
 *
 * @author: linvo
 * @version: 1.0.0
 * @date: 2013/1/10
 */
class Xcrypt{

    private $mcrypt;
    private $key;
    private $mode;
    private $iv;
    private $blocksize;

    /**
     * 构造函数
     *
     * @param string 密钥
     * @param string 模式
     * @param string 向量（"off":不使用 / "auto":自动 / 其他:指定值，长度同密钥）
     */
    public function __construct($key, $mode = 'cbc', $iv = "off"){
        switch (strlen($key)){
            case 8:
                $this->mcrypt = MCRYPT_DES;
                break;
            case 16:
                $this->mcrypt = MCRYPT_RIJNDAEL_128;
                break;
            case 32:
                $this->mcrypt = MCRYPT_RIJNDAEL_256;
                break;
            default:
                die("Key size must be 8/16/32");
        }

        $this->key = $key;

        switch (strtolower($mode)){
            case 'ofb':
                $this->mode = MCRYPT_MODE_OFB;
                if ($iv == 'off') die('OFB must give a IV'); //OFB必须有向量
                break;
            case 'cfb':
                $this->mode = MCRYPT_MODE_CFB;
                if ($iv == 'off') die('CFB must give a IV'); //CFB必须有向量
                break;
            case 'ecb':
                $this->mode = MCRYPT_MODE_ECB;
                $iv = 'off'; //ECB不需要向量
                break;
            case 'cbc':
            default:
                $this->mode = MCRYPT_MODE_CBC;
        }

        switch (strtolower($iv)){
            case "off":
                $this->iv = null;
                break;
            case "auto":
                $source = PHP_OS=='WINNT' ? MCRYPT_RAND : MCRYPT_DEV_RANDOM;
                $this->iv = mcrypt_create_iv(mcrypt_get_block_size($this->mcrypt, $this->mode), $source);
                break;
            default:
                $this->iv = $iv;
        }


    }


    /**
     * 获取向量值
     * @param string 向量值编码（base64/hex/bin）
     * @return string 向量值
     */
    public function getIV($code = 'base64'){
        switch ($code){
            case 'base64':
                $ret = base64_encode($this->iv);
                break;
            case 'hex':
                $ret = bin2hex($this->iv);
                break;
            case 'bin':
            default:
                $ret = $this->iv;
        }
        return $ret;
    }


    /**
     * 加密
     * @param string 明文
     * @param string 密文编码（base64/hex/bin）
     * @return string 密文
     */
    public function encrypt($str, $code = 'base64'){
        if ($this->mcrypt == MCRYPT_DES) $str = $this->_pkcs5Pad($str);

        if (isset($this->iv)) {
            $result = mcrypt_encrypt($this->mcrypt, $this->key, $str, $this->mode, $this->iv);
        } else {
            @$result = mcrypt_encrypt($this->mcrypt, $this->key, $str, $this->mode);
        }

        switch ($code){
            case 'base64':
                $ret = base64_encode($result);
                break;
            case 'hex':
                $ret = bin2hex($result);
                break;
            case 'bin':
            default:
                $ret = $result;
        }

        return $ret;

    }

    /**
     * 解密
     * @param string 密文
     * @param string 密文编码（base64/hex/bin）
     * @return string 明文
     */
    public function decrypt($str, $code = "base64"){
        $ret = false;

        switch ($code){
            case 'base64':
                $str = base64_decode($str);
                break;
            case 'hex':
                $str = $this->_hex2bin($str);
                break;
            case 'bin':
            default:
        }

        if ($str !== false){
            if (isset($this->iv)) {
                $ret = mcrypt_decrypt($this->mcrypt, $this->key, $str, $this->mode, $this->iv);
            } else {
                @$ret = mcrypt_decrypt($this->mcrypt, $this->key, $str, $this->mode);
            }
            if ($this->mcrypt == MCRYPT_DES) $ret = $this->_pkcs5Unpad($ret);
            $ret = trim($ret);
        }

        return $ret;
    }



    private function _pkcs5Pad($text){
        $this->blocksize = mcrypt_get_block_size($this->mcrypt, $this->mode);
        $pad = $this->blocksize - (strlen($text) % $this->blocksize);
        return $text . str_repeat(chr($pad), $pad);
    }

    private function _pkcs5Unpad($text){
        $pad = ord($text{strlen($text) - 1});
        if ($pad > strlen($text)) return false;
        if (strspn($text, chr($pad), strlen($text) - $pad) != $pad) return false;
        $ret = substr($text, 0, -1 * $pad);
        return $ret;
    }

    private function _hex2bin($hex = false){
        $ret = $hex !== false && preg_match('/^[0-9a-fA-F]+$/i', $hex) ? pack("H*", $hex) : false;
        return $ret;
    }
}

$key = '12345678123456781234567812345678'; //256 bit
$key = '1234567812345678'; //128 bit
$key = '12345678'; //64 bit
$a = '12#1abc';
$m = new Xcrypt($key, 'cbc', 'auto');
$b = $m->encrypt($a, 'base64');
var_dump($b);
echo "\r\n";
$c = $m->decrypt($b, 'base64');
echo $c;


转摘来源 http://blog.csdn.net/linvo/article/details/8497056