Trait Hasher

pub trait Hasher<const S: usize>:
    Default
    + Send
    + Sync {
    type Digest: Digest<S>;

    const SIZE: usize = S;

    // Required method
    fn digest(input: &[u8]) -> Self::Digest
       where Self: Sized;
}

Trait implemented by a hash function implementation.

It specifies its own Digest type, so that the output of the hash function can later be distinguished. This way you can create a MultihashDigest from a Digest.

Every hashing algorithm that is used with Multihash needs to implement those. This trait is very similar to the external digest::Digest trait. There is a small significant difference, which needed the introduction of this Hasher trait instead of re-using the widely used digest::Digest trait.

The external digest::Digest trait has a single return type called Output, which is used for all hashers that implement it. It’s basically a wrapper around the hashed result bytes. For Multihashes we need to distinguish those bytes, as we care about which hash function they were created with (which is the whole point of Multihashes). Therefore the Hasher trait defines an associated type Hasher::Digest for the output of the hasher. This way the implementers can specify their own, hasher specific type (which implements Digest) for their output.

Provided Associated Constants

const SIZE: usize = S

the allocated size of the digest.

Required Associated Types

type Digest: Digest<S>

The maximum Digest size for that hasher (it is stack allocated). The Digest type to distinguish the output of different Hasher implementations.

Required Methods

fn digest(input: &[u8]) -> Self::Digest

where Self: Sized,

Hashes the given input data and returns its hash digest.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<T: StatefulHasher<S>, const S: usize> Hasher<S> for T

type Digest = <T as StatefulHasher<S>>::Digest