Crate libp2p::multihash

Expand description

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.