Module vc_derivation_info 

Available on crate feature extensions-draft and crate feature virtual-clients-draft and (32-bit or 64-bit) only.

Virtual-clients-draft derivation chain: types and helpers for the per-commit material the application supplies on the sender side and the receiver re-derives.

Structs

EmulationEpochState

Per-emulation-epoch state persisted by MlsGroup::register_vc_emulation_epoch alongside the per-epoch operation secret tree, keyed by EpochId. Bundles everything the library needs to emit a VC commit for this epoch and to XOR application message nonces with deterministic reuse guards.

EpochId

Identifier of an emulation epoch’s registered virtual-clients state. Derived deterministically from the emulation group’s safe_export_secret(VC_COMPONENT_ID) by MlsGroup::register_vc_emulation_epoch.

GenerationId

A per-message generation ID a virtual client attaches to a fanned-out PrivateMessage so a strongly-consistent DS can detect generation collisions between siblings, per higher-level group, per higher-level group epoch, and per ratchet type (mls-virtual-clients draft).

KeyPackageInfo

Wire struct a virtual client hands to a sibling so the sibling can fetch and process the matching KeyPackage (mls-virtual-clients draft):

KeyPackageSeedSecret

Per-KeyPackage seed secret from which a single KeyPackage’s init and leaf-encryption keys are derived. Produced by OperationSecret::derive_key_package_seed_secret for one index within a key_package operation’s batch. Persisted in RetainedKeyPackageMaterial so the Welcome path can rederive the keys without re-walking the operation tree.

KeyPackageUpload

Wire struct a virtual client uploads to a sibling so the sibling learns about the KeyPackages the virtual client published for an emulation epoch (mls-virtual-clients draft):

OperationSecret

Per-operation secret from which the material for a single virtual-clients operation (commit path, key package, application message) is derived. Produced by the per-epoch Virtual Client Operation Secret Tree (OperationSecretTree). Sender and receiver derive the same value from the same per-epoch state.

RetainedKeyPackageMaterial

Per-KeyPackageRef material a sibling retains when it processes a KeyPackageUpload. It captures what the Welcome path needs to later rederive the KeyPackage’s init and leaf-encryption keys without touching the operation tree: the per-KeyPackage seed secret, plus the emulation epoch, leaf index, generation, and batch index used to validate the leaf found in the ratchet tree.

VcEmulationBindings

Per-higher-level-group record of which emulation-group epoch produced the virtual-client LeafNode that was active at each recent epoch of that group.

Enums

RatchetType

Which ratchet a PrivateMessageContext refers to (mls-virtual-clients draft RatchetType):

VirtualClientOperationType

What virtual-clients operation a per-operation secret is being derived for (mls-virtual-clients draft VirtualClientOperationType). Mixed into the OperationContext of every operation-secret derivation so that secrets derived for different operations cannot collide even if the other fields happen to match.

VirtualClientsError

Errors that can occur while processing virtual-clients derivation info.

Constants

VC_COMPONENT_ID

Component ID under which the virtual-clients derivation info is carried in the leaf node’s app_data_dictionary extension.

Functions

assemble_vc_key_package_upload

Build a KeyPackageUpload for epoch_id from a batch’s generation and its KeyPackageInfo entries, filling leaf_index from the EmulationEpochState stored for that epoch.

process_vc_key_package_upload

Process a KeyPackageUpload received from a sibling virtual client.