Archives/obfs4
2
0
Fork 0
mirror of https://gitlab.com/yawning/obfs4.git synced 2024-11-15 12:12:53 +00:00
Code Issues Projects Releases Wiki Activity
The obfourscator (obfs4proxy)
91 Commits 1 Branch 14 Tags 502 KiB
Go 100%
94d3fe9a08
Go to file
Yawning Angel 94d3fe9a08 Change the TYPE_PRNG_SEED length to 24. 
This matches what the code actually sends.  It's shorter than the
ScrambleSuit PRNG seed, but that's because the SipHash-2-4 based
Hash_DRBG has 24 bytes of internal state (key + initial output).
2014-08-27 12:26:09 +00:00
common Change all the arguments to use base16 from base64. 2014-08-23 05:33:23 +00:00
doc Change the TYPE_PRNG_SEED length to 24. 2014-08-27 12:26:09 +00:00
obfs4proxy Add a ChangeLog and dump the version when invoked with "-v". 2014-08-27 03:46:23 +00:00
transports Display a more useful error on JSON Unmarshall failure. 2014-08-27 03:52:22 +00:00
.gitignore Move to a unified client/server binary, and fix bugs. 2014-05-12 00:02:24 +00:00
ChangeLog Add a ChangeLog and dump the version when invoked with "-v". 2014-08-27 03:46:23 +00:00
LICENSE Document dependencies, add LICENSE (No functional changes). 2014-06-07 20:03:29 +00:00
README.md Massive cleanup/code reorg. 2014-08-17 17:11:03 +00:00

README.md

obfs4 - The obfourscator

Yawning Angel (yawning at torproject dot org)

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).
  • The handshake uses the Tor Project's ntor handshake with public keys obfuscated via the Elligator 2 mapping.
  • The link layer encryption uses NaCl secret boxes (Poly1305/XSalsa20).

As an added bonus, obfs4proxy also supports acting as an obfs2/3 client and bridge to ease the transition to the new protocol.

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.

Dependencies

Build time library dependencies are handled by go get automatically but are listed for clarity.

Thanks

  • David Fifield for goptlib.
  • Adam Langley for his Elligator implementation.
  • Philipp Winter for the ScrambleSuit protocol which provided much of the design.