PHP 7.1版本 微信安全模式消息接受

/**

 * Prpcrypt class

 *

 * 提供接收和推送给公众平台消息的加解密接口.

 */

class Prpcrypt

{

    public $key;

    function __construct($k)

    {

        $this->key = base64_decode($k . "=");

    }

    /**

     * 对明文进行加密

     * @param string $text 需要加密的明文

     * @return string 加密后的密文

     */

    public function encrypt($text, $appid)

    {

        try {

            //获得16位随机字符串，填充到明文之前

            $random = $this->getRandomStr();//"aaaabbbbccccdddd";

            $text = $random . pack("N", strlen($text)) . $text . $appid;

            $iv = substr($this->key, 0, 16);

            $pkc_encoder = new PKCS7Encoder;

            $text = $pkc_encoder->encode($text);

            $encrypted = openssl_encrypt($text,'AES-256-CBC',substr($this->key, 0, 32),OPENSSL_ZERO_PADDING,$iv);

            return array(ErrorCode::$OK, $encrypted);

        } catch (Exception $e) {

            //print $e;

            return array(ErrorCode::$EncryptAESError, null);

        }

    }

    /**

     * 对密文进行解密

     * @param string $encrypted 需要解密的密文

     * @return string 解密得到的明文

     */

    public function decrypt($encrypted, $appid)

    {

        try {

            $iv = substr($this->key, 0, 16);

            $decrypted = openssl_decrypt($encrypted,'AES-256-CBC',substr($this->key, 0, 32),OPENSSL_ZERO_PADDING,$iv);

        } catch (Exception $e) {

            return array(ErrorCode::$DecryptAESError, null);

        }

        try {

            //去除补位字符

            $pkc_encoder = new PKCS7Encoder;

            $result = $pkc_encoder->decode($decrypted);

            //去除16位随机字符串,网络字节序和AppId

            if (strlen($result) < 16)

                return "";

            $content = substr($result, 16, strlen($result));

            $len_list = unpack("N", substr($content, 0, 4));

            $xml_len = $len_list[1];

            $xml_content = substr($content, 4, $xml_len);

            $from_appid = substr($content, $xml_len + 4);

            if (!$appid)

                $appid = $from_appid;

            //如果传入的appid是空的，则认为是订阅号，使用数据中提取出来的appid

        } catch (Exception $e) {

            //print $e;

            return array(ErrorCode::$IllegalBuffer, null);

        }

        if ($from_appid != $appid)

            return array(ErrorCode::$ValidateAppidError, null);

        //不注释上边两行，避免传入appid是错误的情况

        return array(0, $xml_content, $from_appid);

        //增加appid，为了解决后面加密回复消息的时候没有appid的订阅号会无法回复

    }

    /**

     * 随机生成16位字符串

     * @return string 生成的字符串

     */

    function getRandomStr()

    {

        $str = "";

        $str_pol = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";

        $max = strlen($str_pol) - 1;

        for ($i = 0; $i < 16; $i++) {

            $str .= $str_pol[mt_rand(0, $max)];

        }

        return $str;

    }

}