This crate is a no-std, pure Rust impl of the Disco Noise Protocol Extension. It is implemented in an entirely generic way so that the underlying encryption libraries are pluggable by the integrator (that's you). This has not been audited formally yet so it should be considered experimental and not ready for production use.
This implementation is notable in that it supports some of the Advanced
Features listed
in ยง11 of the Noise specification. Specifically, this crate supports
channel binding and out-of-order transport messages. The main difficulty
with out-of-order transport messages is tracking which
nonces you have seen to defend against replay attacks. For small numbers
of messages in a session, this is trivial, but long-lived sessions with
many millions or billions of messages make tracking nonces extremely
difficult. The example implementation in the test folder uses a
simplistic sliding window approach to tracking nonces for demonstration
purposes.
This is not a plug-and-play solution. You will need to do some coding to
make this work for you. There are five traits in this crate that you
must impl with your own chosen cryptography library. They can be found
in src/tag.rs: Tag and TaggedData, src/key.rs: KeyType,
KeyGenerator, and KeyAgreement, and in src/nonce.rs:
NonceGenerator. That said, for the impatient among you, the tests
folder has an example impl and tests of these traits using the common
x25519_dalek crate. It's not difficult to plug your own favorite
cryptography library in, but it is also not trivial. If you don't have a
very good understanding of Noise and Disco, they you should probably
look elsewhere.
This crate supports all of the handshake patterns listed in the Disco
extension documentation: N, K, X, Npsk0, Kpsk0, Xpsk1, NN, KK, XX, IK,
IX, NK, NX, XK1, KK1, and NNpsk2. You can always add your own favorite
handshake to the crate by editing src/params.rs to include it. That
file is well documented and I think it is easy to figure out how to
define a new handshake using the existing code. Please be sure to add
tests for any new handshakes in either tests/one_way.rs or
tests/two_way.rs depending on which handshake you add.
If you are using this crate, I encourage you to drop me a line and send any feedback my way. If you find any issues or have feature requests, please send a PR or file an Issue.