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+## obfs4 - The fourbfuscator
+#### Yawning Angel (yawning at torproject dot org)
+
+### WARNING
+
+This is pre-alpha.  Don't expect any security or wire protocol stability yet.
+If you want to use something like this, you should currently probably be looking
+at ScrambleSuit.
+
+### What?
+
+This is a look-like nothing obfuscation protocol that incorporates ideas and
+concepts from Philipp Winter's ScrambleSuit protocol.  The obfs naming was
+chosen primarily because it was shorter, in terms of protocol ancestery obfs4
+is much closer to ScrambleSuit than obfs2/obfs3.
+
+The notable differences between ScrambleSuit and obfs4:
+
+ * The handshake always does a full key exchange (no such thing as a Session
+   Ticket Handshake). (TODO: Reconsider this.)
+ * The handshake uses the Tor Project's ntor handshake with public keys
+   obfuscated via the Elligator mapping.
+ * The link layer encryption uses NaCl secret boxes (Poly1305/Salsa20).
+
+### Why not extend ScrambleSuit?
+
+It's my protocol and I'll obfuscate if I want to.
+
+Since a lot of the changes are to the handshaking process, it didn't make sense
+to extend ScrambleSuit as writing a server implementation that supported both
+handshake variants without being obscenely slow is non-trivial.
+
+### TODO
+
+ * Packet length obfuscation.
+ * (Maybe) Make it resilient to transient connection loss.
+ * (Maybe) Use IP_MTU/TCP_MAXSEG to tweak frame size.
+ * Write a detailed protocol spec.
+ * Code cleanups.
+ * Write more unit tests.
+
+### WON'T DO
+
+ * I do not care that much about standalone mode.  Patches *MAY* be accepted,
+   especially if they are clean and are useful to Tor users.
+ * Yes, I use a bunch of code from the borg^w^wGoogle.  If that bothers you
+   feel free to write your own implementation.
+ * I do not care about older versions of the go runtime.
+
+### Thanks
+ * David Fifield for goptlib.
+ * Adam Langley for his Elligator implementation.
+ * Philipp Winter for the ScrambleSuit protocol which provided much of the
+   design.