Crate meadowcap

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§Meadowcap

An implementation of Meadowcap, a capability system for permissioning read and write access to the Willow data model.

Includes implementations of communal capabilities, owned capabilities, a type unifying the two, as well as the generation of McAuthorisationTokens for use with the Willow data model’s is_authorised_write parameter.

Willow is a parametrised family of protocols, and so this crate makes heavy use of generic parameters.

The following generic parameter names are used consistently across this crate:

MCL - A usize representing max_component_length.
MCC - A usize representing max_component_count.
MPL - A usize representing max_path_length.
NamespacePublicKey - The type used for NamespacePublicKey (willowprotocol.org), must implement the willow_data_model::NamespaceId trait.
NamespaceSignature - The type used for NamespaceSignature (willowprotocol.org).
UserPublicKey - The type used for UserPublicKey (willowprotocol.org), must implement the SubspaceId trait.
UserSignature - The type used for UserSignature (willowprotocol.org).
PD - The type used for PayloadDigest (willowprotocol.org), must implement the willow_data_model::PayloadDigest trait.

CommunalCapability: A capability that implements communal namespaces.
Delegation: A delegation of access rights to a user for a given area.
McAuthorisationToken: To be used as the AuthorisationToken parameter for the Willow data model.
McSubspaceCapability: A capability that certifies read access to arbitrary SubspaceIds at some unspecified non-empty willow_data_model::Path.
NamespaceIsNotCommunalError: Returned when is_communal unexpectedly mapped a given namespace to false.
NotAWriteCapabilityError: Returned when an operation only applicable to a capability with access mode AccessMode::Write was called on a capability with access mode AccessMode::Read.
OwnedCapability: A capability that implements owned namespaces.
SubspaceDelegation: A delegation of read access for arbitrary SubspaceIds to a UserPublicKey.

AccessMode: A mode granting read or write access to some Area.
FailedDelegationError: Returned when an attempt to delegate a capability to another UserPublicKey failed.
InvalidDelegationError: Returned when an existing delegation was an invalid successor to an existing delegation chain.
McCapability: A Meadowcap capability.
OwnedCapabilityCreationError: Returned when an attempt to create a new owned capability failed.

IsCommunal: Maps namespace public keys to booleans, determining whether that namespace of a particular willow_data_model::NamespaceId is communal or owned.