A minimal and freestanding implementation of SHA-256 in pure Rust.
This implementation is based on the pseudocode on wikipedia and prioritizes readability and simplicity over fancy optimizations. I may optimize it somewhat in the future, but not at the expense of simplicity or readability.
This crate is freestanding (#[no_std]) and has no dependencies,
so it should be just about as portable as it gets. If I add any
dependencies in the future, they will also be freestanding, and
I will keep them behind feature gates.
A small set of tests against known-good hashes are included, but the implementation has not been formally verified. Use at your own risk. I suggest taking a look at the Rust Crypto project for a much more mature implementation which includes various optimizations, as well as a number of useful traits that are shared across a host of different hashers.