# Snow
[](https://crates.io/crates/snow)
[](https://docs.rs/snow)
[](https://travis-ci.org/mcginty/snow)
[](https://deps.rs/repo/github/mcginty/snow)
An implementation of Trevor Perrin's [Noise Protocol](https://noiseprotocol.org/) that is designed to be
Hard To Fuck Upâ„¢.
🔥 **Warning** 🔥 This library has not received any formal audit.
## What's it look like?
See `examples/simple.rs` for a more complete TCP client/server example.
```rust
let mut noise = snow::Builder::new("Noise_NN_25519_ChaChaPoly_BLAKE2s".parse()?)
.build_initiator()?;
let mut buf = [0u8; 65535];
// write first handshake message
noise.write_message(&[], &mut buf)?;
// receive response message
let incoming = receive_message_from_the_mysterious_ether();
noise.read_message(&incoming, &mut buf)?;
// complete handshake, and transition the state machine into transport mode
let mut noise = noise.into_transport_mode()?;
```
See the full documentation at [https://docs.rs/snow](https://docs.rs/snow).
## Implemented
Snow is currently tracking against [Noise spec revision 34](https://noiseprotocol.org/noise_rev34.html).
However, a not all features have been implemented yet (pull requests welcome):
- [ ] [The `fallback` modifier](https://noiseprotocol.org/noise_rev34.html#the-fallback-modifier)
## Crypto
Cryptographic providers are swappable through `Builder::with_resolver()`, but by default it chooses select, artisanal
pure-Rust implementations (see `Cargo.toml` for a quick overview).
### Providers
#### ring
[ring](https://github.com/briansmith/ring) is a crypto library based off of BoringSSL and is significantly faster than most of the pure-Rust implementations.
If you enable the `ring-resolver` feature, Snow will include a `ring_wrapper` module as well as a `RingAcceleratedResolver` available to be used with `Builder::with_resolver()`.
If you enable the `ring-accelerated` feature, Snow will default to choosing `ring`'s crypto implementations when available.
### Resolver primitives supported
| CSPRNG | ✔ | ✔ |
| 25519 | ✔ | ✔ |
| 448 | | |
| AESGCM | | ✔ |
| ChaChaPoly | ✔ | ✔ |
| SHA256 | ✔ | ✔ |
| SHA512 | ✔ | ✔ |
| BLAKE2s | ✔ | |
| BLAKE2b | ✔ | |