The VaultProtocol is a remote-capable irpc service by construction —
#[rpc_requests] generates both Service (local) and RemoteService (remote)
trait impls. DerivedKey's dual serialization (JSON redacts, postcard
preserves) was designed for this. Enabling remote vault access is a
server-setup change, not a protocol change.
OQ-21 enriched with full context:
- What's already in place (protocol, serialization, actor, auth transport)
- What's not in place (IrohProtocol handler forwards all messages without
auth checks; needs NodeId allowlist + message filtering in assembly layer)
- Operation access policy: Unlock/Lock local-only; Derive/Encrypt/Decrypt
remote-capable
- Use case: machine node → workers (workers don't hold mnemonics)
- Per-machine-node vaults, not shared (compartmentalization)
- Breaking vs non-breaking analysis (enabling = non-breaking; protocol
evolution = wire break, manageable via ALPN versioning)
The auth-wrapping handler lives in the assembly layer (or a dedicated
vault-server crate depending on both alknet-core and alknet-vault), not in
the vault crate itself — the vault is standalone (ADR-018) and can't
import alknet-core's auth model.
OQ-21 remains deferred — no commitment to implement, but the door is open
and the design space is mapped.
Key rotation uses version-indexed derivation paths: each key version maps
to a distinct SLIP-0010 path (m/74'/2'/0'/{version-2}'). v2 is at index 0
(PATHS::ENCRYPTION), v3 at index 1, etc.
Mechanism:
- encryption_path_for_version(version) constructs the path
- decrypt derives the key at the version-indicated path (not always
PATHS::ENCRYPTION)
- rotate(blob, to_version) decrypts with old key, re-encrypts with new
- No new mnemonic needed — same seed, different path
- Partial rotation is safe — old keys remain derivable
- The vault does not self-rotate; the assembly layer iterates blobs
Source drift flagged:
- decrypt currently ignores key_version for path selection (always uses
PATHS::ENCRYPTION) — must use version-indexed paths
- rotate method does not exist in source — must be added
- CURRENT_KEY_VERSION must bump from 1 to 2 (per ADR-020, reinforced here)
OQ-22 resolved. Only OQ-21 (remote vault admin, deferred) remains.
The vault uses SLIP-0010 HD derivation from the BIP39 seed for the
AES-256-GCM encryption key, not PBKDF2. This replaces the TypeScript
predecessor's (@alkdev/storage/src/graphs/crypto.ts) PBKDF2-based
approach.
Key decisions:
- HD derivation at m/74'/2'/0'/0' produces the encryption key
- PBKDF2 is not implemented in the vault; no password-based derivation
- salt field is unused in v2 (wire-format compat only)
- key_version=1 reserved for TS PBKDF2 data; key_version=2 for vault HD
- TS-encrypted data requires one-time migration to v2
- CURRENT_KEY_VERSION changes from 1 to 2 (source drift flagged)
OQ-20 resolved: the encryption key derivation method is locked. OQ-22
(key rotation workflow) remains open but does not block implementation.
Spec the vault crate from its existing implementation. The vault is
stable (implementation exists); this spec documents what IS so the
implementation-sync agent can reconcile source drift.
New spec documents (crates/vault/):
- README.md — crate index, security constraints, public API
- mnemonic-derivation.md — BIP39, SLIP-0010, BIP-0032, derivation paths
- encryption.md — AES-256-GCM, EncryptedData, key versioning, salt
- service.md — VaultServiceHandle lifecycle, actor dispatch, cache
- protocol.md — VaultProtocol irpc messages, DerivedKey redaction
New ADRs:
- ADR-018: Vault as standalone crate (zero alknet deps; own types/errors)
- ADR-019: Vault assembly-layer-only access (CLI is sole caller)
New open questions:
- OQ-20: Salt/KDF Phase B (open, low priority — salt field reserved)
- OQ-21: Remote vault administration (deferred — needs ADR if ever needed)
- OQ-22: Key rotation mechanism (open, low priority — workflow not specced)
Spec-vs-source drift explicitly flagged (for the sync agent):
- rand::random() used for IVs instead of OsRng (security-critical)
- unwrap() on every RwLock acquisition (must use unwrap_or_else)
- ADR-038 / OQ-SVC-03 references in source comments are stale (old numbering)
- VaultServiceActor::spawn returns a non-functional second actor (source bug)
- KeyVersionMismatch error variant is defined but unused in v1
