The authorization header is x-kobo-userkey and the header value is your ClientId, which can be found in .kobo/Kobo/Analytics.cong
If you add these custom headers, the kobo servers will start responding. The Kobo eReader requests all data in json format, by using the headers "Accept" - "application/json" and "Accept-Encoding" - "gzip" and "Content-Type" - "application/json". Some data uses "text/json", so every packet must be analyzed one by one.
I also changed the "User-Agent" header to
Code:
"Mozilla/5.0 (Linux; U; Android 2.0; en-us;) AppleWebKit/538.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/538.1 (Kobo Touch)"
as this is what Kobo eReader use.