Sha_256

A fast implementation of sha-256 in rust.

Features

• Partially unrolled loops for increased efficiency from cpu cache usage
• Bypass rust safety checks to eliminate array index safety checks
• Only use stack memory to avoid malloc calls
• Minimised memory footprint via array reuse across multiple stages of sha256
• No memory reallocation, so subsequent calls to sha256 reuse memory
• Optimised memory layout for increased cpu cache hits
• No needless byte array conversion (e.g. u8a to u32a)
• Pure rust, no fancy embedded assembly language or specific cpu instructions
• No dependencies
• No std requirements

Installation

In your project, run:

cargo add sha-256

Usage

The general idea is "bytes in, bytes out". This is the most efficient input and output type to minimise conversions. Consequently, if you want the hash as a hex string you will need to convert it from bytes to hex afterwards - but don't worry, there's a function in this library for exactly that!

fn main() {
    let mut sha256: sha256 = sha256::new();
    // Message can be [u8] or Vec<u8>
    let message: String = "hello".to_string();
    println!("Message: {}", message);
    let messageBytes: &[u8] = message.as_bytes();
    let hash: [u8; 32] = sha256.digest(messageBytes);
    // convert the hash to a hex string
    let hash_hex = sha256::u8a_to_hex(&hash);
    println!("Hash: {}", hash_hex);
}

See the examples dir for a full project example.

Benchmark

How fast is this library? Up to 25% faster than the sha256 and sha, and they contain use of Intel's SHA-NI cpu instructions (via a feature flag).

However, the above figures were obtained through some rough benchmarks on only my hardware. More thorough benchmarks are required, YMMV!

// TODO further benchmarks