Struct FastMultisetHash

pub struct FastMultisetHash { /* private fields */ }

A high‑performance (non‑secure) multiset hash that is order‑independent.

Internally, the state is a 256‑bit value represented as four u64’s. Each element is mapped to a 256‑bit value by a very simple (non‑cryptographic) hash function, and the overall multiset hash is just the sum (with wrapping addition) of all the element hashes. Removal is implemented as subtraction.

This implementation sacrifices cryptographic security for speed.

Implementations

impl FastMultisetHash

pub fn new() -> Self

Creates a new, empty multiset hash (the zero value).

pub fn add(&mut self, data: &[u8])

Adds an element (given as a byte slice) to the multiset hash.

pub fn remove(&mut self, data: &[u8])

Removes an element (given as a byte slice) from the multiset hash.

This is done by subtracting the hash of the element.

pub fn add_elements<'a, T>(&mut self, elements: &'a [T])

where T: AsRef<[u8]> + Sync,

Adds multiple elements in parallel.

pub fn remove_elements<'a, T>(&mut self, elements: &'a [T])

where T: AsRef<[u8]> + Sync,

Removes multiple elements in parallel.

pub fn get_compressed(&self) -> Option<[u8; 32]>

Returns the “compressed” state of the multiset hash as 32 bytes.

(In the secure ECC version this is 33 bytes; here our state is 256 bits so we return 32 bytes.)

pub fn get_digest(&self) -> Option<[u8; 32]>

Returns a 32‑byte digest of the current multiset hash.

For this non‑secure implementation, we simply return the compressed state.