rust crate providing Sphinx packet cryptography
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README.md

rust-sphinxcrypto

This crate provides a concrete parameterization of the Sphinx cryptographic packet format and follows this "Sphinx Mix Network Cryptographic Packet Format Specification" document:

https://github.com/katzenpost/docs/blob/master/specs/sphinx.rst

Sphinx has the following features:

  • Single Use Reply Blocks
  • per hop bitwise unlinkability
  • indistinguishable replies
  • hidden the path length
  • hidden the relay position
  • tagging attack detection
  • reply attack detection

Read the Sphinx paper, Sphinx: A Compact and Provably Secure Mix Format by George Danezis and Ian Goldberg. See https://cypherpunks.ca/~iang/pubs/Sphinx_Oakland09.pdf

warning

This code has not been formally audited by a cryptographer. It therefore should not be considered safe or correct. Use it at your own risk!

details

The currently implemented Sphinx cryptographic parameterization is:

  • EXP(X, Y) - X25519
  • MAC(K, M), H(M) - Blake2b
  • S(K, IV) - Chacha20
  • KDF(SALT, IKM) - SHAKE256
  • SPRP_Encrypt(K, M)/SPRP_Decrypt(K, M) - Lioness composed with: Blake2b and Chacha20.

The Sphinx packet geometry is parameterized in the constants submodule.

Usage

To import sphinxcrypto, add the following to the dependencies section of your project's Cargo.toml:

sphinxcrypto = "^0.0.9"

Then import the crate as:

extern crate sphinxcrypto;

acknowledgments

This library is a Rust language port of Yawning's Katzenpost Sphinx implementation:

https://github.com/katzenpost/core/tree/master/sphinx

These will NOT be binary compatible unless using the exact same cipher suite. I don't have an AEZ cipher implementation written in Rust handy so I will keep using Lioness for the time being. If someone cares about performance then please let me know.

Thanks to Jeff Burdges for helping me with some of my rust problems.

license

GNU AFFERO GENERAL PUBLIC LICENSE