rust-sphinxcrypto

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about

This crate provides a concrete parameterization of the Sphinx cryptographic packet format. Sphinx is used in mix networks, a kind of traffic analysis resistant communications network. Sphinx has recently been used in the design of HORNET and Lightening Onion. Sphinx has the following features:

• Single Use Reply Blocks
• bitwise unlinkability for each hop
• indistinguishable replies
• hiding the path length
• hiding the relay position
• detection of tagging attacks
• detection of reply attacks

Sphinx is described in Sphinx: A Compact and Provably Secure Mix Format by George Danezis and Ian Goldberg. See http://research.microsoft.com/en-us/um/people/gdane/papers/sphinx-eprint.pdf.

If you are interested in using the Sphinx cryptographic packet format in your designs then I recommend at least reading the Security and Anonymity Consideration sections of the "Sphinx Mix Network Cryptographic Packet Format Specification": https://github.com/katzenpost/docs/blob/master/specs/sphinx.txt

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 sodiumoxide crate
• MAC(K, M), H(M) - Blake2b rust-crypto crate
• S(K, IV) - Chacha20 rust-crypto crate
• KDF(SALT, IKM) - SHAKE256 tiny-keccak crate
• SPRPEncrypt(K, M)/SPRPDecrypt(K, M) - Lioness with the following: Blake2b and Chacha20. rust-lioness crate

One of the goals is to remove dependency on the rust-crypto crate, currently I am still using it for Blake2b and Chacha20.

status

Incomplete. Work-in-progress.

acknowledgments

A couple of years ago the initial code here was a partial Sphinx implementation (with only the server side) that Jeff Burdges helped me write. Recently I decided to make this library essentially 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.

license

MIT License