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

EpochId

Identifier of a derivation epoch’s registered virtual-clients state. Derived deterministically from the emulation group’s safe_export_secret(VC_COMPONENT_ID), so every emulator client of a virtual client arrives at the same value for a given derivation 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 a derivation 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.

RegisteredVcDerivationEpochDeprecated

Registration record of the storage layout that preceded the derivation-epoch log. Only for decoding stored records and converting them with VcDerivationEpochLogEntry::from_legacy_record.

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 derivation epoch, leaf index, generation, and batch index used to validate the leaf found in the ratchet tree.

VcDerivationEpochLogEntry

One registration in an emulation group’s log of derivation epochs, stored as its own row keyed by (group_id, epoch_id).

VcDerivationEpochState

Per-derivation-epoch state, persisted alongside the per-epoch operation secret tree and 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.

VcEmulationBinding

The binding of one epoch of a higher-level group to the derivation epoch whose virtual-client LeafNode was active at that epoch, stored as its own row keyed by (group_id, group_epoch).

VcEmulationBindingsDeprecated

Per-group bindings record of the storage layout that preceded per-epoch VcEmulationBinding rows. Only for decoding stored records and converting their entries with VcEmulationBinding::from_legacy_record.

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 VcDerivationEpochState stored for that epoch.

process_vc_key_package_upload

Process a KeyPackageUpload received from a sibling virtual client.