Crate libp2p::multihash

Multihash implementation.

Feature Flags

Multihash has lots of feature flags, by default a table with cryptographically secure hashers is created.

Some of the features are about specific hash functions, these are (“default” marks the hashers that are enabled by default):

• blake2b: (default) Enable Blake2b hashers
• blake2s: (default) Enable Blake2s hashers
• identity: Enable the Identity hashers (using it is discouraged as it’s not a hash function in the sense that it produces a fixed sized output independent of the input size)
• sha1: Enable SHA-1 hasher
• sha2: (default) Enable SHA-2 hashers
• sha3: (default) Enable SHA-3 hashers
• strobe: Enable Strobe hashers

In order to enable all cryptographically secure hashers, you can set the secure-hashes feature flag (enabled by default).

The library has support for no_std, if you disable the std feature flag.

The multihash-impl feature flag (enabled by default) enables a default Multihash implementation that contains some of the bundled hashers. If you want a different set of hash algorithms you can change this with enabled the corresponding features.

For example if you only need SHA2 hasher, you could set the features in the multihash dependency like this:

multihash = { version = …, default-features = false, features = ["std", "multihash-impl", "sha2"] }

If you want to customize your code table even more, for example you want only one specific hash digest size and not whole family, you would only enable the derive feature (enabled by default), which enables the Multihash derive, together with the hashers you want.

The arb feature flag enables the quickcheck arbitrary implementation for property based testing.

For serializing the multihash there is support for Serde via the serde-codec feature and the SCALE Codec via the scale-codec feature.

Modules

derive	This proc macro derives a custom Multihash code table from a list of hashers. It also generates a public type called Multihash which corresponds to the specified alloc_size.
typenum	This crate provides type-level numbers evaluated at compile time. It depends only on libcore.

Structs

IdentityDigest	Multihash digest.
IdentityHasher	Identity hasher with a maximum size.
MultihashGeneric	A Multihash instance that only supports the basic functionality and no hashing.
Sha2Digest	Multihash digest.
Sha2_256	Multihash hasher.
Sha2_512	Multihash hasher.
UnknownDigest	Multihash digest.
WriteHasher	New type wrapper for a hasher that implements the std::io::Write trait.

Enums

Code	Default (cryptographically secure) Multihash implementation.
Error	Multihash error.

Traits

Digest	Stack allocated digest trait.
Hasher	Trait implemented by a hash function implementation.
MultihashDigest	Trait that implements hashing.
Size	Size marker trait.
StatefulHasher	Trait implemented by a hash function implementation.

Type Definitions

Identity256	32 byte Identity hasher (constrained to 32 bytes).
Multihash	A Multihash with the same allocated size as the Multihashes produces by this derive.
Result	Multihash result.
U16
U20
U28
U32
U48
U64
U128