Obfsy McObfsface

Yawning Angel 9ca113c4af Add a LICENSE file, no functional changes. 4 years ago
crypto 2930c076e9 Add more documentation in the form of comments. 4 years ago
ext 0e27e781ae Whiten the 2 high bits in the Elligator2 representative. 4 years ago
framing f71885fdfd Initial import. 4 years ago
handshake 2930c076e9 Add more documentation in the form of comments. 4 years ago
CODE_OF_MERIT.md f71885fdfd Initial import. 4 years ago
LICENSE 9ca113c4af Add a LICENSE file, no functional changes. 4 years ago
README.md e6a7438e6d Add replay detection to obfuscated handshakes. 4 years ago

README.md

basket2 - A transport for the paranoid.

Yawning Angel (yawning at schwanenlied dot me)

basket2 is the next transport in the obfs series. It derives inspiration primarily from obfs4 and predecessors, and incorporates ideas initially prototyped in the experimental basket transport.

Features:

  • Authentication, data integrity, and confidentiality.
  • Active probing resistance.
  • Passive fingerprinting resistance, significantly improved over obfs4.
  • Client driven dynamic negotiation of runtime padding to better suit various adversary models.
  • Better separation between the handshake obfuscation and the authenticated key exchange mechanisms.
  • Significantly improved link layer framing.
  • Optional user authentication.
  • Post-quantum forward secrecy.
  • License switch from 3BSD to AGPL for more Freedom.

Dependencies:

  • Go 1.6.x or later - (May work with older versions, don't care if they don't)
  • golang.org/x/crypto - SHA3, Curve25519, Poly1305
  • github.com/agl/ed25519 - Ed25519, Edwards curve field arithmatic
  • github.com/dchest/siphash - SipHash-2-4
  • git.schwanenlied.me/yawning/chacha20.git - (X)ChaCha20
  • git.schwanenlied.me/yawning/x448.git - X448
  • git.schwanenlied.me/yawning/newhope.git - newhope

Notes:

  • I am waiving the remote network interaction requirements specified in Section 13 ("Remote Network Interaction; Use with the GNU General Public License") of the AGPL, per the terms of Section 7 ("Additional Terms"), for users that:

    • Are using the software to operate a publically accessible Bridge to provide access to the public Tor network as a Tor Pluggable Transport server. This means:

      The Bridge publishes a descriptor to the Bridge Authority, and is available via BridgeDB OR is a default Bridge pre-configured and distributed with Tor Browser.

All other users MUST comply with the AGPL in it's entirety as a general rule, though other licensing arrangements may be possible on request. I will likely be fairly liberal here, so please contact me if the current licensing is unsuitable for your use case.

  • The post-quantum cryptography does not apply to active attackers in posession of a quantum computer, and only will protect pre-existing data from later decryption.

Using a PQ signature algorithm such as SPHINCS256 would solve this problem, however the key and signature sizes are still larger than what I feel comfortable with being able to obfsucate.

  • Yeah, this uses SHA3 instead of whatever trendy BLAKE variant kids like these days.

  • If your system has busted PMTUD, this probably won't work at all. Not my problem. Complain to your OS vendor.

TODO:

  • Write a formal specification.

  • Someone that's not me should write assembly optimized ChaCha20 for ARM and i386. I may do both if I feel bored enough, but no promises.

  • Write optimized assembler versions of things for gccgo (or C if that's easier). Low priority.

  • Define more padding primitives.