rust-sphinxcrypto

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about

This crate provides a concrete parameterization of the Sphinx cryptographic packet format. Although Sphinx is used in mix networks as well as various low latency network designs such as Hornet and Lightening Onion, there is no standardization of this packet format HOWEVER this implementation follows this specification document:

"Sphinx Mix Network Cryptographic Packet Format Specification": https://github.com/katzenpost/docs/blob/master/specs/sphinx.txt

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

Read the Sphinx paper, 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.

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.

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.

license

MIT License