Struct blake3::Hash

pub struct Hash(_);

An output of the default size, 32 bytes, which provides constant-time equality checking.

Hash implements From and Into for [u8; 32], and it provides an explicit as_bytes method returning &[u8; 32]. However, byte arrays and slices don’t provide constant-time equality checking, which is often a security requirement in software that handles private data. Hash doesn’t implement Deref or AsRef, to avoid situations where a type conversion happens implicitly and the constant-time property is accidentally lost.

Hash provides the to_hex method for converting to hexadecimal. It doesn’t directly support converting from hexadecimal, but here’s an example of doing that with the hex crate:

use std::convert::TryInto;

let hash_hex = "d74981efa70a0c880b8d8c1985d075dbcbf679b99a5f9914e5aaf96b831a9e24";
let hash_bytes = hex::decode(hash_hex)?;
let hash_array: [u8; blake3::OUT_LEN] = hash_bytes[..].try_into()?;
let hash: blake3::Hash = hash_array.into();

Implementations

impl Hash

pub fn as_bytes(&self) -> &[u8; 32]

The bytes of the Hash. Note that byte arrays don’t provide constant-time equality checking, so if you need to compare hashes, prefer the Hash type.

pub fn to_hex(&self) -> ArrayString<[u8; 64]>

The hexadecimal encoding of the Hash. The returned ArrayString is a fixed size and doesn’t allocate memory on the heap. Note that ArrayString doesn’t provide constant-time equality checking, so if you need to compare hashes, prefer the Hash type.

Trait Implementations

impl Clone for Hash

fn clone(&self) -> Hash

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Hash

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<[u8; 32]> for Hash

fn from(bytes: [u8; 32]) -> Self

Performs the conversion.

impl From<Hash> for [u8; 32]

fn from(hash: Hash) -> Self

Performs the conversion.

impl Hash for Hash

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given Hasher.

impl PartialEq<[u8; 32]> for Hash

This implementation is constant-time.

fn eq(&self, other: &[u8; 32]) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl PartialEq<Hash> for Hash

This implementation is constant-time.

fn eq(&self, other: &Hash) -> bool

This method tests for self and other values to be equal, and is used by ==.

#[must_use]

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl Copy for Hash

impl Eq for Hash