Aerys\Websocket\Handshake::handshake PHP Method

    private function handshake()
    {
        if ($this->status === 101) {
            $concatKeyStr = $this->acceptKey . self::ACCEPT_CONCAT;
            $secWebSocketAccept = base64_encode(sha1($concatKeyStr, true));
            $this->response->setHeader("Upgrade", "websocket");
            $this->response->setHeader("Connection", "upgrade");
            $this->response->setHeader("Sec-WebSocket-Accept", $secWebSocketAccept);
        }
    }