public function genSig() {

        $appid=''; //替换为自己的
        $identifier='admin'; //可替换为自己的参数
        $expire=86400*180;
        $userbuf='';
        $userbuf_enabled=false;


        $curr_time = time();
        $sig_array = Array(
            'TLS.ver' => '2.0',
            'TLS.identifier' => strval( $identifier ),
            'TLS.sdkappid' => intval( $appid ),
            'TLS.expire' => intval( $expire ),
            'TLS.time' => intval( $curr_time )
        );

        $base64_userbuf = '';
        if ( true == $userbuf_enabled ) {
            $base64_userbuf = base64_encode( $userbuf );
            $sig_array['TLS.userbuf'] = strval( $base64_userbuf );
        }

        $sig_array['TLS.sig'] = $this->hmacsha256( $identifier, $curr_time, $expire, $base64_userbuf, $userbuf_enabled );
        if ( $sig_array['TLS.sig'] === false ) {
            throw new \Exception( 'base64_encode error' );
        }
        $json_str_sig = json_encode( $sig_array );
        if ( $json_str_sig === false ) {
            throw new \Exception( 'json_encode error' );
        }
        $compressed = gzcompress( $json_str_sig );
        if ( $compressed === false ) {
            throw new \Exception( 'gzcompress error' );
        }
        $result = $this->base64_url_encode( $compressed );

        var_dump($result);
        die;
    }

    private function hmacsha256( $identifier, $curr_time, $expire, $base64_userbuf, $userbuf_enabled ) {
        $sdkappid=''; //替换为自己的
        $key=''; //替换为自己的
        $content_to_be_signed = 'TLS.identifier:' . $identifier . "\n"
        . 'TLS.sdkappid:' . $sdkappid . "\n"
        . 'TLS.time:' . $curr_time . "\n"
        . 'TLS.expire:' . $expire . "\n";
        if ( true == $userbuf_enabled ) {
            $content_to_be_signed .= 'TLS.userbuf:' . $base64_userbuf . "\n";
        }
        return base64_encode( hash_hmac( 'sha256', $content_to_be_signed, $key, true ) );
    }

    private function base64_url_encode( $string ) {
        static $replace = Array( '+' => '*', '/' => '-', '=' => '_' );
        $base64 = base64_encode( $string );
        if ( $base64 === false ) {
            throw new \Exception( 'base64_encode error' );
        }
        return str_replace( array_keys( $replace ), array_values( $replace ), $base64 );
    }


    private function base64_url_decode( $base64 ) {
        static $replace = Array( '+' => '*', '/' => '-', '=' => '_' );
        $string = str_replace( array_values( $replace ), array_keys( $replace ), $base64 );
        $result = base64_decode( $string );
        if ( $result == false ) {
            throw new \Exception( 'base64_url_decode error' );
        }
        return $result;
    }