//生成v3 Authorization
    protected function createAuthorization( $url , $method = \'GET\' ){

        if (!in_array(\'sha256WithRSAEncryption\', \openssl_get_md_methods(true))) {
            throw new \RuntimeException("当前PHP环境不支持SHA256withRSA");
        }
        $url_parts = parse_url($url);
        $canonical_url = ($url_parts[\'path\'] . (!empty($url_parts[\'query\']) ? "?${url_parts[\'query\']}" : ""));

        //私钥地址
        $mch_private_key = $this->mch_private_key;
        //商户号
        $merchant_id = $this->mch_id;
        //当前时间戳
        $timestamp =  time();
        //随机字符串
        $nonce = $this->createNoncestr();
        //POST请求时 需要 转JSON字符串
        $body =  $this->body ;
        $message = "{$method}\n".
            $canonical_url."\n".
            $timestamp."\n".
            $nonce."\n".
            $body."\n";

        //生成签名
        openssl_sign($message, $raw_sign, openssl_get_privatekey(file_get_contents($mch_private_key)), \'sha256WithRSAEncryption\');
        $sign = base64_encode($raw_sign);
        //Authorization 类型  
        $schema = \'WECHATPAY2-SHA256-RSA2048\';
        //生成token
        $token = sprintf(\'mchid="%s",serial_no="%s",nonce_str="%s",timestamp="%d",signature="%s"\', $merchant_id,$this->serial_no, $nonce, $timestamp,  $sign);

        $header = [
            \'Content-Type:application/json\',
            \'Accept:application/json\',
            \'User-Agent:*/*\',
            \'Authorization: \'.  $schema . \' \' . $token
        ];
        return $header;
    }

/**
     *  作用：产生随机字符串，不长于32位
     */
    public function createNoncestr( $length = 32 )
    {
        $chars = "abcdefghijklmnopqrstuvwxyz0123456789";
        $str ="";
        for ( $i = 0; $i < $length; $i++ )  {
            $str.= substr($chars, mt_rand(0, strlen($chars)-1), 1);
        }
        return $str;
    }

    
   
   /**
    * 支付及服务 - 服务人员注册
    * 1. 获取平台证书序列号  serial_no与 商户支付证书不是一个
    * 2. 解密平台证书，拿到平台证书信息
    * 3. 加密请求参数时 需要用户 平台证书进行加密 
    */
    public function regguide( $post ,$serial_no){

        $url = "https://api.mch.weixin.qq.com/v3/smartguide/guides";

        $this->setBody( $post );
        //生成V3请求 header认证信息
        $header = $this->createAuthorization( $url , \'POST\' );
        
        //增加平台证书序列号 ， 平台证书序列号方法 getcertificates()   

        $header[] = \'Wechatpay-Serial:\' . $serial_no;
        $data = $this->postXmlCurl(json_encode($post , JSON_UNESCAPED_UNICODE) ,  $url  , 30 , $header );
        return json_decode($data , true);

    }

    /**
     * 获取平台证书， 与商户证书不是一个内容
     */
    public function getcertificates(){

        $url="https://api.mch.weixin.qq.com/v3/certificates";

        //生成V3请求 header认证信息
        $header = $this->createAuthorization( $url );

        $header[] = \'User-Agent : https://zh.wikipedia.org/wiki/User_agent\';

        $data = $this->getXmlCurl( $url  , $this->curl_timeout , $header );

        return json_decode($data , true);

    }

   /**
     * V3加密
     */
    public function getEncrypt($str){ 
        //$str是待加密字符串 
        $public_key_path = \'证书地址\'; //看情况使用证书， 个别接口证书 使用的是 平台证书而不是 api证书
        $public_key = file_get_contents($public_key_path); 
        $encrypted = \'\'; 
        
        if (openssl_public_encrypt($str,$encrypted,$public_key,OPENSSL_PKCS1_OAEP_PADDING)) { 
            //base64编码 
            $sign = base64_encode($encrypted);
        } else {
            throw new Exception(\'encrypt failed\');
        }
        return $sign;
    }


/**
     * Decrypt AEAD_AES_256_GCM ciphertext  V3签名解密
     * @param stingr    $aesKey             V3签名
     * @param string    $associatedData     AES GCM additional authentication data
     * @param string    $nonceStr           AES GCM nonce
     * @param string    $ciphertext         AES GCM cipher text
     *
     * @return string|bool      Decrypted string on success or FALSE on failure
     */
    public function decryptToString($aesKey ,$associatedData, $nonceStr, $ciphertext)
    {

        if (strlen($aesKey) != 32 ) {
            throw new InvalidArgumentException(\'无效的ApiV3Key，长度应为32个字节\');
        }

        $ciphertext = \base64_decode($ciphertext , true);
        if (strlen($ciphertext) <= 16) {
            return false;
        }
        

        // ext-sodium (default installed on >= PHP 7.2)
        if(function_exists(\'\sodium_crypto_aead_aes256gcm_is_available\') && \sodium_crypto_aead_aes256gcm_is_available() ){
            return \sodium_crypto_aead_aes256gcm_decrypt($ciphertext, $associatedData, $nonceStr, $aesKey);
        }

        // ext-libsodium (need install libsodium-php 1.x via pecl)
        if(function_exists(\'\Sodium\crypto_aead_aes256gcm_is_available\') && \Sodium\crypto_aead_aes256gcm_is_available()){

            return \Sodium\crypto_aead_aes256gcm_decrypt($ciphertext, $associatedData, $nonceStr, $aesKey);
        }
        
        // PHP >= 7.1
        if(PHP_VERSION_ID >= 70100 && in_array(\'aes-256-gcm\', \openssl_get_cipher_methods()) ){
            $ctext = substr($ciphertext, 0, -16);
            $authTag = substr($ciphertext, -16);
            return \openssl_decrypt($ctext, \'aes-256-gcm\', $aesKey, \OPENSSL_RAW_DATA, $nonceStr,$authTag, $associatedData);
        }

        throw new \RuntimeException(\'AEAD_AES_256_GCM需要PHP 7.1以上或者安装libsodium-php\');
    }