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## obfs4 - The obfourscator
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#### Yawning Angel (yawning at torproject dot org)
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### WARNING
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This is pre-alpha. Don't expect any security or wire protocol stability yet.
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If you want to use something like this, you should currently probably be looking
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at ScrambleSuit.
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### What?
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This is a look-like nothing obfuscation protocol that incorporates ideas and
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concepts from Philipp Winter's ScrambleSuit protocol. The obfs naming was
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chosen primarily because it was shorter, in terms of protocol ancestery obfs4
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is much closer to ScrambleSuit than obfs2/obfs3.
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The notable differences between ScrambleSuit and obfs4:
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* The handshake always does a full key exchange (no such thing as a Session
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Ticket Handshake).
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* The handshake uses the Tor Project's ntor handshake with public keys
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obfuscated via the Elligator 2 mapping.
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* The link layer encryption uses NaCl secret boxes (Poly1305/XSalsa20).
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### Why not extend ScrambleSuit?
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It's my protocol and I'll obfuscate if I want to.
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Since a lot of the changes are to the handshaking process, it didn't make sense
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to extend ScrambleSuit as writing a server implementation that supported both
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handshake variants without being obscenely slow is non-trivial.
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### TODO
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* Code cleanups.
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* Write more unit tests.
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* Optimize further.
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### WON'T DO
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* I do not care that much about standalone mode. Patches *MAY* be accepted,
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especially if they are clean and are useful to Tor users.
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* Yes, I use a bunch of code from the borg^w^wGoogle. If that bothers you
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feel free to write your own implementation.
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* I do not care about older versions of the go runtime.
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### Thanks
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* David Fifield for goptlib.
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* Adam Langley for his Elligator implementation.
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* Philipp Winter for the ScrambleSuit protocol which provided much of the
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design.
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