This is a API written in C# but it can be used in any .NET language. It's a fork from WhatsAPINet, which is based on WhatsAPI. The goal of this fork is to make it all work again and refacter the code, add documentation and write documentation on how Whatsapp works.

• FunXMPP Protocol - https://github.com/TheKirk/WhatsAPINet/wiki/FunXMPP

The WhatsApp protocol is sadly not officially documented. While working on this project, I will try to document most of my progress in the docs folder.

The protocol is based on the XML-based XMPP protocol, a heavily documented internet messaging protocol. To reduce the XML overhead, the XML structure and a lot of common keywords are converted into bytes. See docs/funxmpp.txt for a more detailed explanation. Sadly, the XMPP standard is not followed exactly everywhere.

• Protocol wrapper: FunXMPP (see Wiki)
• Main protocol: XMPP (http://xmpp.org/rfcs/rfc6120.html)
• Authentification: SASL, digest auth (http://tools.ietf.org/html/rfc2831)
• Blocking: XMPP privacy lists? (http://xmpp.org/extensions/xep-0016.html)
• Ping (http://xmpp.org/extensions/xep-0199.html)

Following the news that WhatsApp messages were sent in plaintext (and thus readable for everyone when on a WiFi hotspot), encryption was added. At least the Android client uses this encryption, which seems to be TLS as specified by the XMPP RFC. However, I did not really look into this. Also, the mapping of keywords to bytes seems to have also changed in the latest version of the Android app.

The current implementation for token generation is created by pastoso.