三重des加密

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class STD3Des
{
    private $key = "";
    private $iv = "";
 
    /**
    * 构造，传递二个已经进行base64_encode的KEY与IV
    *
    * @param string $key
    * @param string $iv
    */
    function __construct ($key, $iv)
    {
        if (empty($key) || empty($iv)) {
            echo 'key and iv is not valid';
            exit();
        }
        $this->key = $key;
        $this->iv = $iv;
    }
 
    /**
    *加密
    * @param$value
    * @return*/
    public function encrypt ($value)
    {
        $td = mcrypt_module_open(MCRYPT_3DES, '', MCRYPT_MODE_CBC, '');
        $iv = base64_decode($this->iv);
        $value = $this->PaddingPKCS7($value);
        $key = base64_decode($this->key);
        mcrypt_generic_init($td, $key, $iv);
        $ret = base64_encode(mcrypt_generic($td, $value));
        mcrypt_generic_deinit($td);
        mcrypt_module_close($td);
        return $ret;
    }
 
    /**
    *解密
    * @param$value
    * @return*/
    public function decrypt ($value)
    {
        $td = mcrypt_module_open(MCRYPT_3DES, '', MCRYPT_MODE_CBC, '');
        $iv = base64_decode($this->iv);
        $key = base64_decode($this->key);
        mcrypt_generic_init($td, $key, $iv);
        $ret = trim(mdecrypt_generic($td, base64_decode($value)));
        $ret = $this->UnPaddingPKCS7($ret);
        mcrypt_generic_deinit($td);
        mcrypt_module_close($td);
        return $ret;
    }
 
    private function PaddingPKCS7 ($data)
    {
        $block_size = mcrypt_get_block_size('tripledes', 'cbc');
        $padding_char = $block_size - (strlen($data) % $block_size);
        $data .= str_repeat(chr($padding_char), $padding_char);
        return $data;
    }
 
    private function UnPaddingPKCS7($text)
    {
        $pad = ord($text{strlen($text) - 1});
        if ($pad > strlen($text)) {
            return false;
        }
        if (strspn($text, chr($pad), strlen($text) - $pad) != $pad) {
            return false;
        }
        return substr($text, 0, - 1 * $pad);
    }
}