Const SipHash implementation for Rust

This crates implements compile-time (const) SipHash-2-4 and SipHash-1-3 in Rust.

It is based on the based on the excellent siphasher crate, which itself is based on the original implementation from rust-core.

It also implements SipHash variants returning 128-bit tags.

The sip module implements the standard 64-bit mode, whereas the sip128 module implements the 128-bit mode.

Usage

In Cargo.toml:

[dependencies]
const-siphasher = "1"

If you want serde support, include the feature like this:

[dependencies]
const-siphasher = { version = "1", features = ["serde"] }

64-bit mode:

use const_siphasher::sip::{SipHasher, SipHasher13, SipHasher24};

// one-shot:

let array: &[u8] = &[1, 2, 3];
let key: &[u8; 16] = &[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16];
let hasher = SipHasher13::new_with_key(key);
let h = hasher.hash(array);

// incremental:

use core::hash::Hasher;

let array1: &[u8] = &[1, 2, 3];
let array2: &[u8] = &[4, 5, 6];
let key: &[u8; 16] = &[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16];
let mut hasher = SipHasher13::new_with_key(key);
hasher.write(array1);
hasher.write(array2);
let h = hasher.finish();

128-bit mode:

use const_siphasher::sip128::{Hasher128, SipHasher, SipHasher13, SipHasher24};

// one-shot:

let array: &[u8] = &[1, 2, 3];
let key: &[u8; 16] = &[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16];
let hasher = SipHasher13::new_with_key(key);
let h = hasher.hash(array).as_bytes();

// incremental:

use core::hash::Hasher;

let array1: &[u8] = &[1, 2, 3];
let array2: &[u8] = &[4, 5, 6];
let key: &[u8; 16] = &[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16];
let mut hasher = SipHasher13::new_with_key(key);
hasher.write(array1);
hasher.write(array2);
let h = hasher.finish128().as_bytes();

API documentation

Note

Due to a confusing and not well documented API, methods from the Hasher trait of the standard library (std::hash::Hasher, core::hash::Hasher) produce non-portable results.

This is not specific to SipHash, and affects all hash functions.

The only safe methods in that trait are write() and finish().

It is thus recommended to use SipHash (and all other hash functions, actually) as documented above.