refactor(custody): drop the single-implementation CustodyStore trait

Reviewed-on: #102
Reviewed-by: Stas <business@jexter.tech>

AGENTS.md

@@ -1,13 +1,16 @@
 # AGENTS.md
 
-This file provides guidance to Codex (Codex.ai/code) when working with code in this repository.
+Guidance for coding agents (Claude Code, Codex, …) working in this repository.
 
 ## Project Overview
 
-Arbiter is a **permissioned signing service** for cryptocurrency wallets. It consists of:
+Arbiter is a **permissioned signing service** for cryptocurrency wallets:
+
 - **`server/`** — Rust gRPC daemon that holds encrypted keys and enforces policies
-- **`operator/`** — Flutter desktop app (macOS/Windows) with a Rust backend via Rinf
-- **`protobufs/`** — Protocol Buffer definitions shared between server and client
+- **`useragent/`** — Flutter app (desktop + mobile + web targets) with a Rust core via `flutter_rust_bridge`
+- **`protobufs/`** — Protocol Buffer definitions shared between server and clients
+- **`docs/`** — `ARCHITECTURE.md` (peer types, flows, threat model) and `IMPLEMENTATION.md`; treat them as the design source of truth and update them when behaviour changes
+- **`scripts/`** — helper scripts, e.g. `gen_erc20_registry.py`
 
 The vault never exposes key material; it only produces signatures when requests satisfy configured policies.
 
@@ -18,7 +21,7 @@ Tools are managed via [mise](https://mise.jdx.dev/). Install all required tools:
 mise install
 ```
 
-Key versions: Rust 1.93.0 (with clippy), Flutter 3.38.9-stable, protoc 29.6, diesel_cli 2.3.6 (sqlite).
+Key versions live in `mise.toml` (currently Rust 1.95.0 with clippy, Flutter 3.41.7-stable, protoc 29.6, diesel_cli 2.3.7 with `sqlite-bundled`, Python 3.14). Also provided there: `cargo-nextest`, `cargo-audit`, `cargo-vet`, `cargo-shear`, `cargo-mutants`, `cargo-features-manager`, `cargo-edit`, `ast-grep`, `flutter_rust_bridge_codegen`.
 
 ## Server (Rust workspace at `server/`)
 
@@ -26,10 +29,14 @@ Key versions: Rust 1.93.0 (with clippy), Flutter 3.38.9-stable, protoc 29.6, die
 
 | Crate | Purpose |
 |---|---|
-| `arbiter-proto` | Generated gRPC stubs + protobuf types; compiled from `protobufs/*.proto` via `tonic-prost-build` |
-| `arbiter-server` | Main daemon — actors, DB, EVM policy engine, gRPC service implementation |
-| `arbiter-operator` | Rust client library for the operator side of the gRPC protocol |
-| `arbiter-client` | Rust client library for SDK clients |
+| `arbiter-proto` | Generated gRPC stubs + protobuf types (`tonic-prost-build`); also `ArbiterUrl`, `home_path()`, `BOOTSTRAP_PATH` |
+| `arbiter-crypto` | Shared crypto primitives: `authn` (ML-DSA), `safecell` (hardened memory), `hashing::Hashable`, re-exported `x-wing` |
+| `arbiter-macros` | `#[derive(Hashable)]` — canonical hashing of structs for the DB integrity layer |
+| `arbiter-server` | Main daemon — actors, peers, DB, EVM policy engine, gRPC service implementation |
+| `arbiter-client` | Rust client library for SDK clients (`ArbiterClient`, EVM wallet, key storage) |
+| `arbiter-tokens-registry` | Generated ERC-20 token registry used by token-transfer policies |
+
+Workspace lints (`server/Cargo.toml`) are strict: most of clippy `pedantic`/`nursery` plus a large restriction set. `as` casts, indexing/slicing, `dbg!`, float arithmetic and undocumented `unsafe` are denied or warned — expect to add an `#[expect(..., reason = "...")]` rather than to silence a lint globally.
 
 ### Common Commands
 
@@ -42,54 +49,78 @@ cargo build
 # Run the server daemon
 cargo run -p arbiter-server
 
-# Run all tests (preferred over cargo test)
+# Run all tests (preferred over cargo test; CI uses --all-features)
 cargo nextest run
 
 # Run a single test
 cargo nextest run <test_name>
 
-# Lint
-cargo clippy
+# Lint (CI runs it with -D warnings)
+cargo clippy --all -- -D warnings
 
 # Security audit
 cargo audit
 
+# Supply-chain review (config in server/supply-chain/)
+cargo vet
+
 # Check unused dependencies
 cargo shear
 
-# Run snapshot tests and update snapshots
-cargo insta review
+# Mutation testing
+cargo mutants
 ```
 
+### CI
+
+Woodpecker pipelines in `.woodpecker/` run on `server/**` changes: `server-lint` (clippy), `server-test` (nextest, `--all-features`), `server-audit`, `server-vet`, plus `useragent-analyze` for the Flutter app.
+
 ### Architecture
 
-The server is actor-based using the **kameo** crate. All long-lived state lives in `GlobalActors`:
+The server is actor-based using the **kameo** crate. Long-lived state lives in `GlobalActors` (`src/actors/mod.rs`):
 
-- **`Bootstrapper`** — Manages the one-time bootstrap token written to `~/.arbiter/bootstrap_token` on first run.
-- **`Vault`** — Holds the encrypted root key and manages the Sealed/Unsealed vault state machine. On unseal, decrypts the root key into a `memsafe` hardened memory cell.
-- **`FlowCoordinator`** — Coordinates cross-connection flow between operators and SDK clients.
-- **`EvmActor`** — Handles EVM transaction policy enforcement and signing.
+- **`Bootstrapper`** — one-time bootstrap token, written to `~/.arbiter/bootstrap_token` on first run
+- **`Vault`** — encrypted root key and the Sealed/Unsealed state machine; on unseal decrypts the root key into a `memsafe`-backed `SafeCell`
+- **`FlowCoordinator`** — cross-connection flow between operators and SDK clients
+- **`OperatorRegistry`** — tracks currently connected operators
+- **`EvmActor`** — EVM transaction policy enforcement and signing
+- **`events`** — a `kameo_actors::MessageBus` (`DeliveryStrategy::Guaranteed`) for cross-actor notifications
 
-Per-connection actors live under `actors/operator/` and `actors/client/`, each with `auth` (challenge-response authentication) and `session` (post-auth operations) sub-modules.
+Per-connection state lives under **`src/peers/`**, not `actors/`: `peers/client/` and `peers/operator/`, each with `auth` (challenge-response) and `session` (post-auth) sub-modules; the operator side additionally has `vault_gate/` for the unseal handshake.
 
-**Database:** SQLite via `diesel-async` + `bb8` connection pool. Schema managed by embedded Diesel migrations in `crates/arbiter-server/migrations/`. DB file lives at `~/.arbiter/arbiter.sqlite`. Tests use a temp-file DB via `db::create_test_pool()`.
+The gRPC surface lives in **`src/grpc/`**, split per peer (`client/`, `operator/`, `common/`) and per direction (`inbound.rs` — requests to the daemon, `outbound.rs` — server-initiated streams), with `request_tracker.rs` correlating the two.
+
+EVM logic is in `src/evm/`: `policies/ether_transfer/`, `policies/token_transfers/`, `abi.rs`, `safe_signer.rs`.
+
+**Database:** SQLite via `diesel-async` + `bb8`. Schema in `src/db/schema.rs`, models in `src/db/models.rs`, embedded migrations in `crates/arbiter-server/migrations/`. DB file lives at `~/.arbiter/arbiter.sqlite`; tests use a temp-file DB via `db::create_test_pool()`.
+
+Entity ids are newtypes generated by the `declare_id!` macro in `db::models` (`OperatorId`, `ChainId`, …), each a `#[repr(transparent)]` wrapper over `i32` with `to_raw`/`from_raw`. Pass these around instead of bare `i32`.
+
+**Row integrity:** sensitive rows are covered by an HMAC-SHA256 envelope (`src/crypto/integrity/`, table `integrity_envelope`), keyed from the vault root key. A struct becomes coverable by deriving `arbiter_macros::Hashable` and implementing `Integrable` (`KIND` + `VERSION`). When adding or changing a covered entity, keep the derive and the payload version in sync — a mismatch surfaces as `PayloadVersionMismatch` or `MacMismatch` at runtime.
 
 **Cryptography:**
-- Authentication: ed25519 (challenge-response, nonce-tracked per peer)
-- Encryption at rest: XChaCha20-Poly1305 (versioned via `scheme` field for transparent migration on unseal)
+- Authentication: **ML-DSA-87** (post-quantum, `arbiter-crypto::authn::v1`), challenge-response with per-peer nonce tracking
+- Encryption at rest: XChaCha20-Poly1305, versioned modules (`crypto/encryption/v1.rs`) with a `schema_version` column for transparent migration on unseal
 - Password KDF: Argon2
-- Unseal transport: X25519 ephemeral key exchange
-- TLS: self-signed certificate (aws-lc-rs backend), fingerprint distributed via `ArbiterUrl`
+- Unseal transport: X25519 ephemeral key exchange (`peers/operator/vault_gate/`); `x-wing` (hybrid PQ KEM) is available via `arbiter-crypto`
+- TLS: self-signed certificate (rustls + aws-lc-rs, `prefer-post-quantum`), fingerprint distributed via `ArbiterUrl`
 
-**Protocol:** gRPC with Protocol Buffers. The `ArbiterUrl` type encodes host, port, CA cert, and bootstrap token into a single shareable string (printed to console on first run).
+Crypto modules are versioned by convention: `mod.rs` re-exports the current `vN`. Add a `v(N+1)` rather than editing an existing version in place.
+
+**Protocol:** gRPC with Protocol Buffers. `ArbiterUrl` encodes host, port, CA cert and bootstrap token into a single shareable string (printed to console on first run).
 
 ### Proto Regeneration
 
-When `.proto` files in `protobufs/` change, rebuild to regenerate:
+`arbiter-proto/build.rs` compiles `arbiter.proto`, `operator.proto`, `client.proto` and `evm.proto` (with their `shared/`, `operator/`, `client/` includes) on build:
 ```sh
 cd server && cargo build -p arbiter-proto
 ```
 
+Dart protobuf stubs are generated separately, from the repo root:
+```sh
+mise run codegen   # protoc --dart_out=grpc:useragent/lib/proto
+```
+
 ### Database Migrations
 
 ```sh
@@ -100,6 +131,8 @@ diesel migration generate <name> --migration-dir crates/arbiter-server/migration
 diesel migration run --migration-dir crates/arbiter-server/migrations
 ```
 
+Pre-release policy: there is a single `init` migration and no deployed databases yet, so schema changes are made by editing that migration directly instead of stacking new ones. Regenerate `src/db/schema.rs` after changing it.
+
 ### Code Conventions
 
 **`#[must_use]` Attribute:**
@@ -121,29 +154,23 @@ pub fn verify(&self, nonce: i32, context: &[u8], signature: &Signature) -> bool
 
 This forces callers to either use the return value or explicitly ignore it with `let _ = ...;`, preventing silent failures.
 
-## Operator (Flutter + Rinf at `operator/`)
+## User Agent (Flutter + flutter_rust_bridge at `useragent/`)
 
-The Flutter app uses [Rinf](https://rinf.cunarist.org) to call Rust code. The Rust logic lives in `operator/native/hub/` as a separate crate that uses `arbiter-operator` for the gRPC client.
-
-Communication between Dart and Rust uses typed **signals** defined in `operator/native/hub/src/signals/`. After modifying signal structs, regenerate Dart bindings:
-
-```sh
-cd operator && rinf gen
-```
+The Flutter app calls Rust through [flutter_rust_bridge](https://cjycode.com/flutter_rust_bridge/) 2.12.0. The Rust side is the `rust_lib_arbiter` crate at `useragent/rust/`; everything exposed to Dart is declared in `useragent/rust/src/api/` and lands in `useragent/lib/src/rust/` (see `useragent/flutter_rust_bridge.yaml`). Dart UI code is organised as `lib/features/`, `lib/screens/`, `lib/widgets/`, `lib/providers/`, `lib/theme/`, with routing in `lib/router.dart` (`router.gr.dart` is generated).
 
 ### Common Commands
 
 ```sh
-cd operator
+cd useragent
 
-# Run the app (macOS or Windows)
+# Run the app
 flutter run
 
-# Regenerate Rust↔Dart signal bindings
-rinf gen
+# Regenerate Rust↔Dart bindings after editing rust/src/api/
+mise run codegen        # flutter_rust_bridge_codegen generate
 
-# Analyze Dart code
+# Analyze Dart code (also run in CI)
 flutter analyze
 ```
 
-The Rinf Rust entry point is `operator/native/hub/src/lib.rs`. It spawns actors defined in `operator/native/hub/src/actors/` which handle Dart↔server communication via signals.
+Note: `app/` contains only stale generated Flutter artifacts and is not the application source.

app/.dart_tool/extension_discovery/README.md

@@ -1,31 +0,0 @@
-Extension Discovery Cache
-=========================
-
-This folder is used by `package:extension_discovery` to cache lists of
-packages that contains extensions for other packages.
-
-DO NOT USE THIS FOLDER
-----------------------
-
- * Do not read (or rely) the contents of this folder.
- * Do write to this folder.
-
-If you're interested in the lists of extensions stored in this folder use the
-API offered by package `extension_discovery` to get this information.
-
-If this package doesn't work for your use-case, then don't try to read the
-contents of this folder. It may change, and will not remain stable.
-
-Use package `extension_discovery`
----------------------------------
-
-If you want to access information from this folder.
-
-Feel free to delete this folder
--------------------------------
-
-Files in this folder act as a cache, and the cache is discarded if the files
-are older than the modification time of `.dart_tool/package_config.json`.
-
-Hence, it should never be necessary to clear this cache manually, if you find a
-need to do please file a bug.

app/.dart_tool/extension_discovery/vs_code.json

@@ -1 +0,0 @@
-{"version":2,"entries":[{"package":"app","rootUri":"../","packageUri":"lib/"}]}

app/.dart_tool/package_config.json

@@ -1,178 +0,0 @@
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "async",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/async-2.13.0",
-      "packageUri": "lib/",
-      "languageVersion": "3.4"
-    },
-    {
-      "name": "boolean_selector",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/boolean_selector-2.1.2",
-      "packageUri": "lib/",
-      "languageVersion": "3.1"
-    },
-    {
-      "name": "characters",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/characters-1.4.0",
-      "packageUri": "lib/",
-      "languageVersion": "3.4"
-    },
-    {
-      "name": "clock",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/clock-1.1.2",
-      "packageUri": "lib/",
-      "languageVersion": "3.4"
-    },
-    {
-      "name": "collection",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/collection-1.19.1",
-      "packageUri": "lib/",
-      "languageVersion": "3.4"
-    },
-    {
-      "name": "cupertino_icons",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/cupertino_icons-1.0.8",
-      "packageUri": "lib/",
-      "languageVersion": "3.1"
-    },
-    {
-      "name": "fake_async",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/fake_async-1.3.3",
-      "packageUri": "lib/",
-      "languageVersion": "3.3"
-    },
-    {
-      "name": "flutter",
-      "rootUri": "file:///Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable/packages/flutter",
-      "packageUri": "lib/",
-      "languageVersion": "3.8"
-    },
-    {
-      "name": "flutter_lints",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/flutter_lints-6.0.0",
-      "packageUri": "lib/",
-      "languageVersion": "3.8"
-    },
-    {
-      "name": "flutter_test",
-      "rootUri": "file:///Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable/packages/flutter_test",
-      "packageUri": "lib/",
-      "languageVersion": "3.8"
-    },
-    {
-      "name": "leak_tracker",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/leak_tracker-11.0.2",
-      "packageUri": "lib/",
-      "languageVersion": "3.2"
-    },
-    {
-      "name": "leak_tracker_flutter_testing",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/leak_tracker_flutter_testing-3.0.10",
-      "packageUri": "lib/",
-      "languageVersion": "3.2"
-    },
-    {
-      "name": "leak_tracker_testing",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/leak_tracker_testing-3.0.2",
-      "packageUri": "lib/",
-      "languageVersion": "3.2"
-    },
-    {
-      "name": "lints",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/lints-6.1.0",
-      "packageUri": "lib/",
-      "languageVersion": "3.8"
-    },
-    {
-      "name": "matcher",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/matcher-0.12.17",
-      "packageUri": "lib/",
-      "languageVersion": "3.4"
-    },
-    {
-      "name": "material_color_utilities",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/material_color_utilities-0.11.1",
-      "packageUri": "lib/",
-      "languageVersion": "2.17"
-    },
-    {
-      "name": "meta",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/meta-1.17.0",
-      "packageUri": "lib/",
-      "languageVersion": "3.5"
-    },
-    {
-      "name": "path",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/path-1.9.1",
-      "packageUri": "lib/",
-      "languageVersion": "3.4"
-    },
-    {
-      "name": "sky_engine",
-      "rootUri": "file:///Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable/bin/cache/pkg/sky_engine",
-      "packageUri": "lib/",
-      "languageVersion": "3.8"
-    },
-    {
-      "name": "source_span",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/source_span-1.10.2",
-      "packageUri": "lib/",
-      "languageVersion": "3.1"
-    },
-    {
-      "name": "stack_trace",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/stack_trace-1.12.1",
-      "packageUri": "lib/",
-      "languageVersion": "3.4"
-    },
-    {
-      "name": "stream_channel",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/stream_channel-2.1.4",
-      "packageUri": "lib/",
-      "languageVersion": "3.3"
-    },
-    {
-      "name": "string_scanner",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/string_scanner-1.4.1",
-      "packageUri": "lib/",
-      "languageVersion": "3.1"
-    },
-    {
-      "name": "term_glyph",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/term_glyph-1.2.2",
-      "packageUri": "lib/",
-      "languageVersion": "3.1"
-    },
-    {
-      "name": "test_api",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/test_api-0.7.7",
-      "packageUri": "lib/",
-      "languageVersion": "3.5"
-    },
-    {
-      "name": "vector_math",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/vector_math-2.2.0",
-      "packageUri": "lib/",
-      "languageVersion": "3.1"
-    },
-    {
-      "name": "vm_service",
-      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/vm_service-15.0.2",
-      "packageUri": "lib/",
-      "languageVersion": "3.5"
-    },
-    {
-      "name": "app",
-      "rootUri": "../",
-      "packageUri": "lib/",
-      "languageVersion": "3.10"
-    }
-  ],
-  "generator": "pub",
-  "generatorVersion": "3.10.8",
-  "flutterRoot": "file:///Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable",
-  "flutterVersion": "3.38.9",
-  "pubCache": "file:///Users/kaska/.pub-cache"
-}

app/.dart_tool/package_graph.json

@@ -1,230 +0,0 @@
-{
-  "roots": [
-    "app"
-  ],
-  "packages": [
-    {
-      "name": "app",
-      "version": "1.0.0+1",
-      "dependencies": [
-        "cupertino_icons",
-        "flutter"
-      ],
-      "devDependencies": [
-        "flutter_lints",
-        "flutter_test"
-      ]
-    },
-    {
-      "name": "flutter_lints",
-      "version": "6.0.0",
-      "dependencies": [
-        "lints"
-      ]
-    },
-    {
-      "name": "flutter_test",
-      "version": "0.0.0",
-      "dependencies": [
-        "clock",
-        "collection",
-        "fake_async",
-        "flutter",
-        "leak_tracker_flutter_testing",
-        "matcher",
-        "meta",
-        "path",
-        "stack_trace",
-        "stream_channel",
-        "test_api",
-        "vector_math"
-      ]
-    },
-    {
-      "name": "cupertino_icons",
-      "version": "1.0.8",
-      "dependencies": []
-    },
-    {
-      "name": "flutter",
-      "version": "0.0.0",
-      "dependencies": [
-        "characters",
-        "collection",
-        "material_color_utilities",
-        "meta",
-        "sky_engine",
-        "vector_math"
-      ]
-    },
-    {
-      "name": "lints",
-      "version": "6.1.0",
-      "dependencies": []
-    },
-    {
-      "name": "stream_channel",
-      "version": "2.1.4",
-      "dependencies": [
-        "async"
-      ]
-    },
-    {
-      "name": "meta",
-      "version": "1.17.0",
-      "dependencies": []
-    },
-    {
-      "name": "collection",
-      "version": "1.19.1",
-      "dependencies": []
-    },
-    {
-      "name": "leak_tracker_flutter_testing",
-      "version": "3.0.10",
-      "dependencies": [
-        "flutter",
-        "leak_tracker",
-        "leak_tracker_testing",
-        "matcher",
-        "meta"
-      ]
-    },
-    {
-      "name": "vector_math",
-      "version": "2.2.0",
-      "dependencies": []
-    },
-    {
-      "name": "stack_trace",
-      "version": "1.12.1",
-      "dependencies": [
-        "path"
-      ]
-    },
-    {
-      "name": "clock",
-      "version": "1.1.2",
-      "dependencies": []
-    },
-    {
-      "name": "fake_async",
-      "version": "1.3.3",
-      "dependencies": [
-        "clock",
-        "collection"
-      ]
-    },
-    {
-      "name": "path",
-      "version": "1.9.1",
-      "dependencies": []
-    },
-    {
-      "name": "matcher",
-      "version": "0.12.17",
-      "dependencies": [
-        "async",
-        "meta",
-        "stack_trace",
-        "term_glyph",
-        "test_api"
-      ]
-    },
-    {
-      "name": "test_api",
-      "version": "0.7.7",
-      "dependencies": [
-        "async",
-        "boolean_selector",
-        "collection",
-        "meta",
-        "source_span",
-        "stack_trace",
-        "stream_channel",
-        "string_scanner",
-        "term_glyph"
-      ]
-    },
-    {
-      "name": "sky_engine",
-      "version": "0.0.0",
-      "dependencies": []
-    },
-    {
-      "name": "material_color_utilities",
-      "version": "0.11.1",
-      "dependencies": [
-        "collection"
-      ]
-    },
-    {
-      "name": "characters",
-      "version": "1.4.0",
-      "dependencies": []
-    },
-    {
-      "name": "async",
-      "version": "2.13.0",
-      "dependencies": [
-        "collection",
-        "meta"
-      ]
-    },
-    {
-      "name": "leak_tracker_testing",
-      "version": "3.0.2",
-      "dependencies": [
-        "leak_tracker",
-        "matcher",
-        "meta"
-      ]
-    },
-    {
-      "name": "leak_tracker",
-      "version": "11.0.2",
-      "dependencies": [
-        "clock",
-        "collection",
-        "meta",
-        "path",
-        "vm_service"
-      ]
-    },
-    {
-      "name": "term_glyph",
-      "version": "1.2.2",
-      "dependencies": []
-    },
-    {
-      "name": "string_scanner",
-      "version": "1.4.1",
-      "dependencies": [
-        "source_span"
-      ]
-    },
-    {
-      "name": "source_span",
-      "version": "1.10.2",
-      "dependencies": [
-        "collection",
-        "path",
-        "term_glyph"
-      ]
-    },
-    {
-      "name": "boolean_selector",
-      "version": "2.1.2",
-      "dependencies": [
-        "source_span",
-        "string_scanner"
-      ]
-    },
-    {
-      "name": "vm_service",
-      "version": "15.0.2",
-      "dependencies": []
-    }
-  ],
-  "configVersion": 1
-}

app/.dart_tool/version

@@ -1 +0,0 @@
-3.38.9

mise.lock

@@ -152,5 +152,8 @@ url = "https://github.com/astral-sh/python-build-standalone/releases/download/20
 provenance = "github-attestations"
 
 [[tools.rust]]
-version = "1.95.0"
+version = "1.98.1"
 backend = "core:rust"
+
+[tools.rust.options]
+components = "clippy,rust-analyzer"

mise.toml

@@ -4,7 +4,7 @@
 "cargo:cargo-vet" = "0.10.2"
 flutter = "3.41.7-stable"
 protoc = "29.6"
-rust = { version = "1.95.0", components = "clippy,rust-analyzer" }
+rust = { version = "latest", components = "clippy,rust-analyzer" }
 "cargo:cargo-features-manager" = "0.12.0"
 "cargo:cargo-nextest" = "0.9.133"
 "cargo:cargo-shear" = "latest"

protobufs/operator.proto

@@ -4,25 +4,28 @@ package arbiter.operator;
 
 import "operator/auth.proto";
 import "operator/evm.proto";
+import "operator/governance.proto";
 import "operator/sdk_client.proto";
 import "operator/vault/vault.proto";
 
 message OperatorRequest {
   int32 id = 16;
   oneof payload {
-    auth.Request auth = 1;
-    vault.Request vault = 2;
-    evm.Request evm = 3;
-    sdk_client.Request sdk_client = 4;
+    auth.Request            auth        = 1;
+    vault.Request           vault       = 2;
+    evm.Request             evm         = 3;
+    sdk_client.Request      sdk_client  = 4;
+    governance.Request      governance  = 5;
   }
 }
 
 message OperatorResponse {
   optional int32 id = 16;
   oneof payload {
-    auth.Response auth = 1;
-    vault.Response vault = 2;
-    evm.Response evm = 3;
-    sdk_client.Response sdk_client = 4;
+    auth.Response           auth        = 1;
+    vault.Response          vault       = 2;
+    evm.Response            evm         = 3;
+    sdk_client.Response     sdk_client  = 4;
+    governance.Response     governance  = 5;
   }
 }

protobufs/operator/governance.proto

@@ -0,0 +1,136 @@
+syntax = "proto3";
+
+package arbiter.operator.governance;
+
+message Request {
+  oneof payload {
+    CreateProposalRequest create = 1;
+    CastVoteRequest       vote   = 2;
+    QueryPendingRequest   query  = 3;
+  }
+}
+
+message CreateProposalRequest {
+  oneof kind {
+    ApproveSdkClientPayload         approve_sdk_client          = 1;
+    GrantWalletAccessPayload        grant_wallet_access         = 3;
+    ApproveServerUpdatePayload      approve_server_update       = 4;
+    ReplaceOperatorPayload          replace_operator            = 5;
+    UpdateShamirParametersPayload   update_shamir_parameters    = 6;
+    ApprovePersistentGrantPayload   approve_persistent_grant    = 7;
+    ApproveOneOffTransactionPayload approve_one_off_transaction = 8;
+  }
+  optional uint32 ttl_secs = 2;
+}
+
+message ReplaceOperatorPayload {
+  int32 old_operator_id = 1;
+  bytes new_pubkey      = 2;
+}
+
+message UpdateShamirParametersPayload {
+  uint32 new_n = 1;
+}
+
+message ApproveServerUpdatePayload {}
+
+message ApproveSdkClientPayload {
+  int32 client_id = 1;
+}
+
+message GrantWalletAccessPayload {
+  int32 wallet_id = 1;
+  int32 client_id = 2;
+}
+
+message CastVoteRequest {
+  int32 proposal_id = 1;
+  bool  approve     = 2;
+  bytes signature   = 3;
+}
+
+message QueryPendingRequest {}
+
+message Response {
+  oneof payload {
+    CreateProposalResponse created = 1;
+    VoteResponse           voted   = 2;
+    QueryPendingResponse   pending = 3;
+  }
+}
+
+message CreateProposalResponse {
+  int32 proposal_id = 1;
+}
+
+message VoteResponse {
+  VoteOutcome outcome = 1;
+}
+
+enum VoteOutcome {
+  VOTE_OUTCOME_UNSPECIFIED = 0;
+  VOTE_OUTCOME_PENDING     = 1;
+  VOTE_OUTCOME_APPROVED    = 2;
+  VOTE_OUTCOME_REJECTED    = 3;
+}
+
+message ProposalSummary {
+  int32  id            = 1;
+  string kind          = 2;
+  int32  initiator_id  = 3;
+  int64  expires_at    = 4;
+  int64  approve_count = 5;
+  int64  reject_count  = 6;
+}
+
+message QueryPendingResponse {
+  repeated ProposalSummary proposals = 1;
+}
+
+message TransactionRateLimitProto {
+  uint32 count       = 1;
+  int64  window_secs = 2;
+}
+
+message VolumeLimitProto {
+  bytes max_volume  = 1;
+  int64 window_secs = 2;
+}
+
+message EtherTransferSpecProto {
+  repeated bytes   targets = 1;
+  VolumeLimitProto limit   = 2;
+}
+
+message TokenTransferSpecProto {
+  bytes                     token_contract = 1;
+  optional bytes            target         = 2;
+  repeated VolumeLimitProto volume_limits  = 3;
+}
+
+message ApproveOneOffTransactionPayload {
+  int32  client_id                = 1;
+  bytes  wallet_address           = 2;
+  uint64 chain_id                 = 3;
+  uint64 nonce                    = 4;
+  uint64 gas_limit                = 5;
+  bytes  max_fee_per_gas          = 6;
+  bytes  max_priority_fee_per_gas = 7;
+  bytes  to                       = 8;
+  bytes  value                    = 9;
+  bytes  input                    = 10;
+}
+
+message ApprovePersistentGrantPayload {
+  int32                              wallet_access_id         = 1;
+  uint64                             chain_id                 = 2;
+  optional int64                     valid_from_secs          = 3;
+  optional int64                     valid_until_secs         = 4;
+  optional bytes                     max_gas_fee_per_gas      = 5;
+  optional bytes                     max_priority_fee_per_gas = 6;
+  optional TransactionRateLimitProto rate_limit               = 7;
+  oneof specific {
+    EtherTransferSpecProto ether_transfer = 8;
+    TokenTransferSpecProto token_transfer = 9;
+  }
+}

protobufs/operator/vault/bootstrap.proto

@@ -8,15 +8,35 @@ message BootstrapEncryptedKey {
   bytes associated_data = 3;
 }
 
+message DeclareCommittee {
+  uint32 count          = 1;
+  uint32 recovery_count = 2;
+}
+
+message ContributePassphrase {
+  bytes passphrase = 1;
+}
+
+message ContributeRecoveryPassphrase {
+  int32 recovery_operator_id = 1;
+  bytes passphrase            = 2;
+}
+
 enum BootstrapResult {
   BOOTSTRAP_RESULT_UNSPECIFIED = 0;
   BOOTSTRAP_RESULT_SUCCESS = 1;
   BOOTSTRAP_RESULT_ALREADY_BOOTSTRAPPED = 2;
   BOOTSTRAP_RESULT_INVALID_KEY = 3;
+  BOOTSTRAP_RESULT_AWAITING_CONTRIBUTIONS = 4;
 }
 
 message Request {
-  BootstrapEncryptedKey encrypted_key = 2;
+  oneof payload {
+    BootstrapEncryptedKey        encrypted_key                    = 2;
+    DeclareCommittee             declare_committee                = 3;
+    ContributePassphrase         contribute_passphrase            = 4;
+    ContributeRecoveryPassphrase contribute_recovery_passphrase   = 5;
+  }
 }
 
 message Response {

protobufs/operator/vault/rekey.proto

@@ -0,0 +1,30 @@
+syntax = "proto3";
+
+package arbiter.operator.vault.rekey;
+
+message ContributePassphrase {
+  bytes passphrase = 1;
+}
+
+message ContributeRecoveryPassphrase {
+  int32 recovery_operator_id = 1;
+  bytes passphrase           = 2;
+}
+
+enum RekeyResult {
+  REKEY_RESULT_UNSPECIFIED            = 0;
+  REKEY_RESULT_SUCCESS                = 1;
+  REKEY_RESULT_AWAITING_CONTRIBUTIONS = 2;
+  REKEY_RESULT_NOT_IN_PROGRESS        = 3;
+}
+
+message Request {
+  oneof payload {
+    ContributePassphrase         contribute_passphrase          = 1;
+    ContributeRecoveryPassphrase contribute_recovery_passphrase = 2;
+  }
+}
+
+message Response {
+  RekeyResult result = 1;
+}

protobufs/operator/vault/unseal.proto

@@ -15,18 +15,29 @@ message UnsealEncryptedKey {
   bytes associated_data = 3;
 }
 
+message ContributePassphrase {
+  bytes passphrase = 1;
+}
+
+message ContributeRecoveryPassphrase {
+  int32 recovery_operator_id = 1;
+  bytes passphrase            = 2;
+}
+
 enum UnsealResult {
   UNSEAL_RESULT_UNSPECIFIED = 0;
   UNSEAL_RESULT_SUCCESS = 1;
   UNSEAL_RESULT_INVALID_KEY = 2;
   UNSEAL_RESULT_UNBOOTSTRAPPED = 3;
-  UNSEAL_RESULT_LOCKED_OUT = 4;
+  UNSEAL_RESULT_AWAITING_CONTRIBUTIONS = 4;
 }
 
 message Request {
   oneof payload {
-    UnsealStart start = 1;
-    UnsealEncryptedKey encrypted_key = 2;
+    UnsealStart                  start                          = 1;
+    UnsealEncryptedKey           encrypted_key                  = 2;
+    ContributePassphrase         contribute_passphrase          = 3;
+    ContributeRecoveryPassphrase contribute_recovery_passphrase = 4;
   }
 }
 

protobufs/operator/vault/vault.proto

@@ -5,20 +5,23 @@ package arbiter.operator.vault;
 import "google/protobuf/empty.proto";
 import "shared/vault.proto";
 import "operator/vault/bootstrap.proto";
+import "operator/vault/rekey.proto";
 import "operator/vault/unseal.proto";
 
 message Request {
   oneof payload {
     google.protobuf.Empty query_state = 1;
-    unseal.Request unseal = 2;
-    bootstrap.Request bootstrap = 3;
+    unseal.Request        unseal      = 2;
+    bootstrap.Request     bootstrap   = 3;
+    rekey.Request         rekey       = 4;
   }
 }
 
 message Response {
   oneof payload {
-    arbiter.shared.VaultState state = 1;
-    unseal.Response unseal = 2;
-    bootstrap.Response bootstrap = 3;
+    arbiter.shared.VaultState state     = 1;
+    unseal.Response           unseal    = 2;
+    bootstrap.Response        bootstrap = 3;
+    rekey.Response            rekey     = 4;
   }
 }

protobufs/shared/vault.proto

@@ -5,7 +5,8 @@ package arbiter.shared;
 enum VaultState {
   VAULT_STATE_UNSPECIFIED = 0;
   VAULT_STATE_UNBOOTSTRAPPED = 1;
-  VAULT_STATE_SEALED = 2;
-  VAULT_STATE_UNSEALED = 3;
-  VAULT_STATE_ERROR = 4;
+  VAULT_STATE_BOOSTRAPPING = 2;
+  VAULT_STATE_SEALED = 3;
+  VAULT_STATE_UNSEALED = 4;
+  VAULT_STATE_ERROR = 5;
 }

server/Cargo.toml

@@ -6,34 +6,34 @@ resolver = "3"
 
 
 [workspace.dependencies]
-alloy = "2.4.1"
-async-trait = "0.1.92"
-base64 = "0.23.1"
-chrono = { version = "0.4.45", features = ["serde"] }
-futures = "0.3.34"
+alloy = "2.0.4"
+async-trait = "0.1.89"
+base64 = "0.22.1"
+chrono = { version = "0.4.44", features = ["serde"] }
+futures = "0.3.32"
 k256 = { version = "0.13.4", features = ["ecdsa", "pkcs8"] }
-kameo = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
-kameo_actors = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
+kameo = {git = "https://github.com/hdbg/kameo.git", rev = "3bbebac"}
+kameo_actors = {git = "https://github.com/hdbg/kameo.git", rev = "3bbebac"}
 hmac = "0.13.0"
 miette = { version = "7.6.0", features = ["fancy", "serde"] }
-ml-dsa = { version = "0.1.1", features = ["zeroize"] }
+ml-dsa = { version = "0.1.0-rc.9", features = ["zeroize"] }
 mutants = "0.0.4"
-prost = "0.14.4"
-prost-types = { version = "0.14.4", features = ["chrono"] }
-rand = "0.10.2"
+prost = "0.14.3"
+prost-types = { version = "0.14.3", features = ["chrono"] }
+rand = "0.10.1"
 rand_core = "0.10.1"
-rcgen = { version = "0.14.9", features = [ "aws_lc_rs",  "pem", "x509-parser", "zeroize" ], default-features = false }
+rcgen = { version = "0.14.7", features = [ "aws_lc_rs",  "pem", "x509-parser", "zeroize" ], default-features = false }
 rstest = "0.26.1"
-rustls = { version = "0.23.43", features = ["aws-lc-rs", "logging", "prefer-post-quantum", "std"], default-features = false }
-rustls-pki-types = "1.15.1"
+rustls = { version = "0.23.40", features = ["aws-lc-rs", "logging", "prefer-post-quantum", "std"], default-features = false }
+rustls-pki-types = "1.14.1"
 sha2 = "0.11"
 smlang = "0.8.0"
-thiserror = "2.0.20"
-tokio = { version = "1.53.1", features = ["full"] }
-tokio-stream = { version = "0.1.19", features = ["full"] }
-tonic = { version = "0.14.6", features = [ "deflate", "gzip", "tls-connect-info", "zstd" ] }
+thiserror = "2.0.18"
+tokio = { version = "1.52.1", features = ["full"] }
+tokio-stream = { version = "0.1.18", features = ["full"] }
+tonic = { version = "0.14.5", features = [ "deflate", "gzip", "tls-connect-info", "zstd" ] }
 tracing = "0.1.44"
-x25519-dalek = { version = "3.0.0", features = ["getrandom"] }
+x25519-dalek = { version = "2.0.1", features = ["getrandom"] }
 
 [workspace.lints.rust]
 missing_unsafe_on_extern = "deny"
@@ -78,6 +78,7 @@ pub_underscore_fields = "allow"
 redundant_pub_crate = "allow" 
 uninhabited_references = "allow" # safe with unsafe_code = "forbid" and standard uninhabited pattern (match *self {})
 too-many-lines = "allow" # this is a very common pattern in server code, and it's not always possible to break it down into smaller modules without hurting readability
+unused_async_trait_impl = "allow" # too pedantic
 
 # restriction lints
 alloc_instead_of_core = "warn"

server/crates/arbiter-client/Cargo.toml

@@ -20,8 +20,8 @@ tonic.features = ["tls-aws-lc"]
 tokio.workspace = true
 tokio-stream.workspace = true
 thiserror.workspace = true
-http = "1.5.0"
-rustls-webpki = { version = "0.103.15", features = ["aws-lc-rs"] }
+http = "1.4.0"
+rustls-webpki = { version = "0.103.13", features = ["aws-lc-rs"] }
 async-trait.workspace = true
 chrono.workspace = true
 

server/crates/arbiter-client/src/client.rs

@@ -94,7 +94,6 @@ impl ArbiterClient {
     }
 
     #[cfg(feature = "evm")]
-    #[expect(clippy::unused_async, reason = "false positive")]
     pub async fn evm_wallets(&self) -> Result<Vec<ArbiterEvmWallet>, ArbiterClientError> {
         todo!("fetch EVM wallet list from server")
     }

server/crates/arbiter-crypto/Cargo.toml

@@ -6,10 +6,10 @@ edition = "2024"
 [dependencies]
 ml-dsa = {workspace = true, optional = true }
 rand = {workspace = true, optional = true}
-memsafe = {version = "1.0.2", optional = true}
+memsafe = {version = "0.4.0", optional = true}
 hmac.workspace = true
 alloy.workspace = true
-x-wing = { version = "0.1.0", features = ["zeroize"] }
+x-wing = { version = "0.1.0-rc.0", features = ["zeroize"] }
 chrono.workspace = true
 thiserror.workspace = true
 

server/crates/arbiter-crypto/src/authn/v1.rs

@@ -1,8 +1,8 @@
 use chrono::{DateTime, Utc};
 use hmac::digest::Digest;
 use ml_dsa::{
-    EncodedVerifyingKey, Error, ExpandedSigningKey, Generate, MlDsa87, Seed,
-    Signature as MlDsaSignature, SigningKey as MlDsaSigningKey, VerifyingKey as MlDsaVerifyingKey,
+    EncodedVerifyingKey, Error, KeyGen, MlDsa87, Seed, Signature as MlDsaSignature,
+    SigningKey as MlDsaSigningKey, VerifyingKey as MlDsaVerifyingKey, signature::Keypair as _,
 };
 use rand::RngExt;
 
@@ -77,10 +77,7 @@ impl crate::hashing::Hashable for PublicKey {
 pub struct Signature(Box<MlDsaSignature<KeyParams>>);
 
 #[derive(Debug)]
-pub struct SigningKey {
-    key: Box<ExpandedSigningKey<KeyParams>>,
-    seed: Seed,
-}
+pub struct SigningKey(Box<MlDsaSigningKey<KeyParams>>);
 
 impl PublicKey {
     pub fn to_bytes(&self) -> Vec<u8> {
@@ -103,31 +100,24 @@ impl Signature {
 
 impl SigningKey {
     pub fn generate() -> Self {
-        let seed = MlDsaSigningKey::<KeyParams>::generate_from_rng(&mut rand::rng()).to_seed();
-        Self {
-            key: Box::new(ExpandedSigningKey::from_seed(&seed)),
-            seed,
-        }
+        Self(Box::new(KeyParams::key_gen(&mut rand::rng())))
     }
 
     pub fn from_seed(seed: [u8; 32]) -> Self {
-        let seed = Seed::from(seed);
-        Self {
-            key: Box::new(ExpandedSigningKey::from_seed(&seed)),
-            seed,
-        }
+        Self(Box::new(KeyParams::from_seed(&Seed::from(seed))))
     }
 
     pub fn to_seed(&self) -> [u8; 32] {
-        self.seed.into()
+        self.0.to_seed().into()
     }
 
     pub fn public_key(&self) -> PublicKey {
-        self.key.verifying_key().into()
+        self.0.verifying_key().into()
     }
 
     pub fn sign_message(&self, message: &[u8], context: &[u8]) -> Result<Signature, Error> {
-        self.key
+        self.0
+            .signing_key()
             .sign_deterministic(message, context)
             .map(Into::into)
     }
@@ -155,6 +145,12 @@ impl From<MlDsaSignature<KeyParams>> for Signature {
     }
 }
 
+impl From<MlDsaSigningKey<KeyParams>> for SigningKey {
+    fn from(value: MlDsaSigningKey<KeyParams>) -> Self {
+        Self(Box::new(value))
+    }
+}
+
 impl TryFrom<Vec<u8>> for PublicKey {
     type Error = ();
 
@@ -192,15 +188,15 @@ impl TryFrom<&'_ [u8]> for Signature {
 
 #[cfg(test)]
 mod tests {
-    use ml_dsa::{Generate as _, MlDsa87, SigningKey as RealSigningKey, signature::Keypair as _};
+    use ml_dsa::{KeyGen, MlDsa87, signature::Keypair as _};
 
     use crate::authn::AuthChallenge;
 
-    use super::{CLIENT_CONTEXT, OPERATOR_CONTEXT, PublicKey, Signature, SigningKey};
+    use super::{CLIENT_CONTEXT, PublicKey, Signature, SigningKey, OPERATOR_CONTEXT};
 
     #[test]
     fn public_key_round_trip_decodes() {
-        let key = RealSigningKey::<MlDsa87>::generate();
+        let key = MlDsa87::key_gen(&mut rand::rng());
         let encoded = PublicKey::from(key.verifying_key()).to_bytes();
 
         let decoded = PublicKey::try_from(encoded.as_slice()).expect("public key should decode");

server/crates/arbiter-macros/Cargo.toml

@@ -10,7 +10,7 @@ doctest = false
 [dependencies]
 proc-macro2 = "1.0"
 quote = "1.0"
-syn = { version = "3.0", features = ["derive", "fold", "full", "visit-mut"] }
+syn = { version = "2.0", features = ["derive", "fold", "full", "visit-mut"] }
 
 [dev-dependencies]
 arbiter-crypto = { path = "../arbiter-crypto" }

server/crates/arbiter-proto/Cargo.toml

@@ -9,7 +9,7 @@ license = "Apache-2.0"
 tonic.workspace = true
 tokio.workspace = true
 futures.workspace = true
-tonic-prost = "0.14.6"
+tonic-prost = "0.14.5"
 prost.workspace = true
 kameo.workspace = true
 url = "2.5.8"
@@ -22,7 +22,7 @@ async-trait.workspace = true
 tokio-stream.workspace = true
 
 [build-dependencies]
-tonic-prost-build = "0.14.6"
+tonic-prost-build = "0.14.5"
 
 [dev-dependencies]
 rstest.workspace = true

server/crates/arbiter-proto/src/lib.rs

@@ -23,6 +23,10 @@ pub mod proto {
             tonic::include_proto!("arbiter.operator.evm");
         }
 
+        pub mod governance {
+            tonic::include_proto!("arbiter.operator.governance");
+        }
+
         pub mod sdk_client {
             tonic::include_proto!("arbiter.operator.sdk_client");
         }
@@ -34,6 +38,10 @@ pub mod proto {
                 tonic::include_proto!("arbiter.operator.vault.bootstrap");
             }
 
+            pub mod rekey {
+                tonic::include_proto!("arbiter.operator.vault.rekey");
+            }
+
             pub mod unseal {
                 tonic::include_proto!("arbiter.operator.vault.unseal");
             }

server/crates/arbiter-server/Cargo.toml

@@ -9,14 +9,8 @@ license = "Apache-2.0"
 workspace = true
 
 [dependencies]
-diesel = { version = "2.3.12", features = [
-    "chrono",
-    "returning_clauses_for_sqlite_3_35",
-    "serde_json",
-    "time",
-    "uuid",
-] }
-diesel-async = { version = "0.9.2", features = [
+diesel = { version = "2.3.9", features = ["chrono", "returning_clauses_for_sqlite_3_35", "serde_json", "time", "uuid"] }
+diesel-async = { version = "0.9.0", features = [
     "bb8",
     "migrations",
     "sqlite",
@@ -41,22 +35,23 @@ rand_core.workspace = true
 rcgen.workspace = true
 chrono.workspace = true
 kameo.workspace = true
-chacha20poly1305 = { version = "0.11.0" }
-argon2 = { version = "0.6.0", features = ["zeroize"] }
+chacha20poly1305 = { version = "0.10.1", features = ["std"] }
+argon2 = { version = "0.5.3", features = ["zeroize"] }
 restructed = "0.2.2"
 strum = { version = "0.28.0", features = ["derive"] }
-pem = "4.0.0"
+pem = "3.0.6"
 sha2.workspace = true
 hmac.workspace = true
 alloy.workspace = true
 prost-types.workspace = true
 arbiter-tokens-registry.path = "../arbiter-tokens-registry"
-anyhow = "1.0.104"
+anyhow = "1.0.102"
 mutants.workspace = true
 subtle = "2.6.1"
 x25519-dalek.workspace = true
 k256.workspace = true
 kameo_actors.workspace = true
+vsss-rs = "6.0.1"
 
 [dev-dependencies]
 proptest = "1.11.0"

server/crates/arbiter-server/migrations/2026-02-14-171124-0000_init/up.sql

@@ -37,7 +37,8 @@ create table if not exists tls_history (
 create table if not exists arbiter_settings (
     id INTEGER not null PRIMARY KEY CHECK (id = 1), -- singleton row, id must be 1
     root_key_id integer references root_key_history (id) on delete RESTRICT, -- if null, means wasn't bootstrapped yet
-    tls_id integer references tls_history (id) on delete RESTRICT
+    tls_id integer references tls_history (id) on delete RESTRICT,
+    shamir_threshold integer
 ) STRICT;
 
 insert into arbiter_settings (id) values (1) on conflict do nothing;
@@ -56,6 +57,7 @@ create table if not exists operator (
 
     share blob not null,
     share_nonce blob not null,
+    share_salt blob not null,
 
     created_at integer not null default(unixepoch ('now')),
     updated_at integer not null default(unixepoch ('now'))

server/crates/arbiter-server/src/actors/bootstrap.rs

@@ -1,119 +1,160 @@
-use crate::db::{self, DatabasePool, schema};
+use crate::{
+    actors::vault::events,
+    db::{self, schema},
+};
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_proto::{BOOTSTRAP_PATH, home_path};
 
 use diesel::QueryDsl;
 use diesel_async::RunQueryDsl;
-use kameo::{Actor, messages};
+use kameo::{
+    Actor,
+    actor::ActorRef,
+    messages,
+    prelude::{Context, Message},
+};
+use kameo_actors::message_bus::{MessageBus, Register};
 use rand::{RngExt, distr::Alphanumeric, rngs::SysRng};
 use rand_core::UnwrapErr;
 use std::path::{Path, PathBuf};
 use subtle::ConstantTimeEq as _;
-use thiserror::Error;
 use tracing::warn;
 
 const TOKEN_LENGTH: usize = 64;
 
 async fn write_token_file(path: &Path, content: &str) -> Result<(), std::io::Error> {
+    if let Some(parent) = path.parent() {
+        tokio::fs::create_dir_all(parent).await?;
+    }
     tokio::fs::write(path, content.as_bytes()).await?;
-
     #[cfg(unix)]
     {
         use std::os::unix::fs::PermissionsExt as _;
         tokio::fs::set_permissions(path, std::fs::Permissions::from_mode(0o600)).await?;
     }
-
     Ok(())
 }
 
+async fn remove_token_file(path: &Path) {
+    match tokio::fs::remove_file(path).await {
+        Ok(()) => {}
+        Err(error) if error.kind() == std::io::ErrorKind::NotFound => {}
+        Err(error) => warn!(?error, ?path, "Failed to remove bootstrap token file"),
+    }
+}
+
 async fn generate_token(path: &Path) -> Result<SafeCell<[u8; TOKEN_LENGTH]>, std::io::Error> {
     let mut cell = SafeCell::new([0u8; TOKEN_LENGTH]);
     {
         let mut buf = cell.write();
-        for (slot, b) in buf
+        for (slot, byte) in buf
             .iter_mut()
             .zip(UnwrapErr(SysRng).sample_iter(Alphanumeric))
         {
-            *slot = b;
+            *slot = byte;
         }
     }
-
-    let token_str = cell.read_inline(|buf| String::from_utf8_lossy(buf.as_ref()).into_owned());
-
-    write_token_file(path, &token_str).await?;
-
+    let token = cell.read_inline(|buf| String::from_utf8_lossy(buf.as_ref()).into_owned());
+    write_token_file(path, &token).await?;
     Ok(cell)
 }
 
-#[derive(Error, Debug)]
+#[derive(Debug, thiserror::Error)]
 pub enum Error {
     #[error("Database error: {0}")]
     Database(#[from] db::PoolError),
-
     #[error("I/O error: {0}")]
     Io(#[from] std::io::Error),
-
     #[error("Database query error: {0}")]
     Query(#[from] diesel::result::Error),
 }
 
-#[derive(Actor)]
+/// Custodian of the one-time bootstrap token.
+///
+/// The token authorises registering operator identities before the vault
+/// exists. A Shamir committee needs every member registered before it can be
+/// declared, so the token stays valid across several registrations and is
+/// retired by the `Bootstrapped` event rather than by first use, whichever
+/// bootstrap path fired it.
+///
+/// Every daemon start mints a fresh token and overwrites the file: a token
+/// handed out by an earlier run is dead.
 pub struct Bootstrapper {
     token: Option<SafeCell<[u8; TOKEN_LENGTH]>>,
     token_path: Option<PathBuf>,
+    events: ActorRef<MessageBus>,
 }
 
-impl Bootstrapper {
-    pub async fn new(db: &DatabasePool) -> Result<Self, Error> {
-        let row_count: i64 = {
-            let mut conn = db.get().await?;
+impl Actor for Bootstrapper {
+    type Args = Self;
+    type Error = std::convert::Infallible;
 
-            schema::operator::table
-                .count()
-                .get_result(&mut conn)
-                .await?
-        };
-
-        let (token, token_path) = if row_count == 0 {
-            let path = home_path()?.join(BOOTSTRAP_PATH);
-            let token = generate_token(&path).await?;
-            (Some(token), Some(path))
-        } else {
-            (None, None)
-        };
-
-        Ok(Self { token, token_path })
+    async fn on_start(args: Self::Args, actor_ref: ActorRef<Self>) -> Result<Self, Self::Error> {
+        let _ = args
+            .events
+            .tell(Register(actor_ref.recipient::<events::Bootstrapped>()))
+            .await;
+        Ok(args)
     }
 }
 
 impl Bootstrapper {
-    fn is_correct_token(&mut self, token: &[u8]) -> bool {
-        self.token.as_mut().is_some_and(|expected| {
-            expected.read_inline(|exp| bool::from(exp.as_ref().ct_eq(token)))
+    pub async fn new(db: &db::DatabasePool, events: ActorRef<MessageBus>) -> Result<Self, Error> {
+        let path = home_path()?.join(BOOTSTRAP_PATH);
+        let mut conn = db.get().await?;
+
+        let bootstrapped = schema::arbiter_settings::table
+            .select(schema::arbiter_settings::root_key_id)
+            .first::<Option<i32>>(&mut conn)
+            .await?
+            .is_some();
+        if bootstrapped {
+            // A token file can outlive the bootstrap that made it obsolete:
+            // the daemon may have been killed before the event was handled.
+            remove_token_file(&path).await;
+            return Ok(Self {
+                token: None,
+                token_path: None,
+                events,
+            });
+        }
+
+        Ok(Self {
+            token: Some(generate_token(&path).await?),
+            token_path: Some(path),
+            events,
         })
     }
-}
 
-#[messages]
-impl Bootstrapper {
-    #[message]
-    pub async fn consume_token(&mut self, token: Vec<u8>) -> bool {
-        if self.is_correct_token(&token) {
-            self.token = None;
-            if let Some(path) = self.token_path.take()
-                && let Err(e) = tokio::fs::remove_file(&path).await
-            {
-                warn!(error = ?e, path = ?path, "Failed to delete bootstrap token file after consumption");
-            }
-            true
-        } else {
-            false
+    async fn forget(&mut self) {
+        self.token = None;
+        if let Some(path) = self.token_path.take() {
+            remove_token_file(&path).await;
         }
     }
 }
 
+impl Message<events::Bootstrapped> for Bootstrapper {
+    type Reply = ();
+
+    async fn handle(
+        &mut self,
+        _: events::Bootstrapped,
+        _ctx: &mut Context<Self, Self::Reply>,
+    ) -> Self::Reply {
+        self.forget().await;
+    }
+}
+    
 #[messages]
 impl Bootstrapper {
+    #[message]
+    pub fn verify_token(&mut self, token: Vec<u8>) -> bool {
+        self.token.as_mut().is_some_and(|expected| {
+            expected.read_inline(|bytes| bool::from(bytes.as_ref().ct_eq(token.as_slice())))
+        })
+    }
+
     #[message]
     pub fn get_token(&mut self) -> Option<String> {
         self.token

server/crates/arbiter-server/src/actors/mod.rs

@@ -1,7 +1,7 @@
 use crate::{
     actors::{
         bootstrap::Bootstrapper, evm::EvmActor, flow_coordinator::FlowCoordinator,
-        operator_registry::OperatorRegistry, vault::Vault,
+        operator_registry::OperatorRegistry, vault::Vault, vault_coordinator::VaultCoordinator,
     },
     db,
 };
@@ -15,20 +15,22 @@ pub mod evm;
 pub mod flow_coordinator;
 pub mod operator_registry;
 pub mod vault;
+pub mod vault_coordinator;
 
 #[derive(Error, Debug)]
 pub enum SpawnError {
     #[error("Failed to spawn Bootstrapper actor")]
     Bootstrapper(#[from] bootstrap::Error),
-
     #[error("Failed to spawn Vault actor")]
     Vault(#[from] vault::Error),
+    #[error("Failed to spawn VaultCoordinator actor")]
+    VaultCoordinator(#[from] vault_coordinator::Error),
 }
 
-/// Long-lived actors that are shared across all connections and handle global state and operations
 #[derive(Clone)]
 pub struct GlobalActors {
     pub vault: ActorRef<Vault>,
+    pub vault_coordinator: ActorRef<VaultCoordinator>,
     pub bootstrapper: ActorRef<Bootstrapper>,
     pub flow_coordinator: ActorRef<FlowCoordinator>,
     pub operator_registry: ActorRef<OperatorRegistry>,
@@ -42,18 +44,22 @@ impl GlobalActors {
     }
 
     pub async fn spawn(db: db::DatabasePool) -> Result<Self, SpawnError> {
-        let message_bus = Self::spawn_message_bus();
-        let key_holder = Vault::spawn(Vault::new(db.clone(), message_bus.clone()).await?);
+        let events = Self::spawn_message_bus();
+        let vault = Vault::spawn(Vault::new(db.clone(), events.clone()).await?);
+        let bootstrapper = Bootstrapper::spawn(Bootstrapper::new(&db, events.clone()).await?);
+        let vault_coordinator =
+            VaultCoordinator::spawn(VaultCoordinator::new(db.clone(), vault.clone()));
         let operator_registry = OperatorRegistry::spawn(OperatorRegistry::default());
         Ok(Self {
-            bootstrapper: Bootstrapper::spawn(Bootstrapper::new(&db).await?),
-            evm: EvmActor::spawn(EvmActor::new(key_holder.clone(), db)),
-            vault: key_holder,
+            bootstrapper,
+            evm: EvmActor::spawn(EvmActor::new(vault.clone(), db.clone())),
+            vault,
+            vault_coordinator,
             flow_coordinator: FlowCoordinator::spawn(FlowCoordinator::new(
                 operator_registry.clone(),
             )),
             operator_registry,
-            events: message_bus,
+            events,
         })
     }
 }

server/crates/arbiter-server/src/actors/operator_registry.rs

@@ -20,8 +20,8 @@ impl Actor for OperatorRegistry {
 
     type Error = Infallible;
 
-    async fn on_start(args: Self::Args, _: ActorRef<Self>) -> Result<Self, Self::Error> {
-        Ok(args)
+    fn on_start(args: Self::Args, _: ActorRef<Self>) -> impl Future<Output = Result<Self, Self::Error>> {
+        std::future::ready(Ok(args))
     }
 
     async fn on_link_died(

server/crates/arbiter-server/src/actors/vault/mod.rs

@@ -1,15 +1,17 @@
 use crate::{
     crypto::{
-        KeyCell, derive_key,
+        KeyCell,
         encryption::v1::{self, Nonce},
         integrity::v1::HmacSha256,
     },
     db::{
         self,
+        custody::{self, CustodyRecord},
         models::{self, RootKeyHistory, RootKeyHistoryId},
         schema::{self},
     },
 };
+
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 
 use chrono::Utc;
@@ -60,6 +62,9 @@ pub enum Error {
     #[error("Database transaction error: {0}")]
     DatabaseTransaction(#[from] diesel::result::Error),
 
+    #[error("Custody storage error: {0}")]
+    Custody(#[from] custody::Error),
+
     #[error("Broken database")]
     BrokenDatabase,
 
@@ -118,7 +123,12 @@ impl Vault {
             }
         };
 
-        Ok(Self { db, state, events, unseal_failures: 0 })
+        Ok(Self {
+            db,
+            state,
+            events,
+            unseal_failures: 0,
+        })
     }
 
     // Exclusive transaction to avoid race condtions if multiple vaults write
@@ -167,13 +177,16 @@ impl Vault {
         }
     }
 
+    /// Create the root key and take the vault into the unsealed state.
     #[message]
-    pub async fn bootstrap(&mut self, seal_key_raw: SafeCell<Vec<u8>>) -> Result<(), Error> {
+    pub async fn bootstrap(
+        &mut self,
+        mut seal_key: KeyCell,
+        custody: Option<CustodyRecord>,
+    ) -> Result<(), Error> {
         if !matches!(self.state, State::Unbootstrapped) {
             return Err(Error::AlreadyBootstrapped);
         }
-        let salt = v1::generate_salt();
-        let mut seal_key = derive_key(seal_key_raw, &salt);
         let mut root_key = KeyCell::new_secure_random();
 
         // Zero nonces are fine because they are one-time
@@ -202,7 +215,7 @@ impl Vault {
                         root_key_encryption_nonce: root_key_nonce.to_vec(),
                         data_encryption_nonce: data_encryption_nonce_bytes.clone(),
                         schema_version: 1,
-                        salt: salt.to_vec(),
+                        salt: v1::generate_salt().to_vec(),
                     })
                     .returning(schema::root_key_history::id)
                     .get_result(&mut *conn)
@@ -213,9 +226,11 @@ impl Vault {
                     .execute(&mut *conn)
                     .await?;
 
-                Result::<_, diesel::result::Error>::Ok(RootKeyHistoryId::from_raw(
-                    root_key_history_id,
-                ))
+                if let Some(record) = custody.as_ref() {
+                    custody::write_record(&mut *conn, record).await?;
+                }
+
+                Result::<_, Error>::Ok(RootKeyHistoryId::from_raw(root_key_history_id))
             })
             .await?;
 
@@ -231,7 +246,7 @@ impl Vault {
     }
 
     #[message]
-    pub async fn try_unseal(&mut self, seal_key_raw: SafeCell<Vec<u8>>) -> Result<(), Error> {
+    pub async fn try_unseal(&mut self, mut seal_key: KeyCell) -> Result<(), Error> {
         if self.unseal_failures >= MAX_UNSEAL_ATTEMPTS {
             return Err(Error::LockedOut);
         }
@@ -253,13 +268,6 @@ impl Vault {
                 .await?
         };
 
-        let salt = &current_key.salt;
-        let salt = v1::Salt::try_from(salt.as_slice()).map_err(|_| {
-            error!("Broken database: invalid salt for root key");
-            Error::BrokenDatabase
-        })?;
-        let mut seal_key = derive_key(seal_key_raw, &salt);
-
         let mut root_key = SafeCell::new(current_key.ciphertext.clone());
 
         let nonce =
@@ -442,8 +450,6 @@ impl Vault {
 #[cfg(test)]
 mod tests {
     use crate::actors::GlobalActors;
-    use crate::db::models::RootKeyHistory;
-    use arbiter_crypto::safecell::SafeCellHandle as _;
 
     use super::*;
 
@@ -451,8 +457,8 @@ mod tests {
         let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
             .await
             .unwrap();
-        let seal_key = SafeCell::new(b"test-seal-key".to_vec());
-        actor.bootstrap(seal_key).await.unwrap();
+        let seal_key = KeyCell::from([0u8; 32]);
+        actor.bootstrap(seal_key, None).await.unwrap();
         actor
     }
 

server/crates/arbiter-server/src/actors/vault_coordinator/mod.rs

@@ -0,0 +1,378 @@
+//! Coordinates the multi-operator ceremonies that create and open the vault.
+//!
+//! The coordinator collects one passphrase per committee member, then hands the
+//! assembled material to [`Vault`] in a single message. It owns no Diesel code:
+//! everything it reads or writes goes through [`db::custody`].
+
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use argon2::RECOMMENDED_SALT_LEN;
+use kameo::{Actor, actor::ActorRef, error::SendError, messages};
+use rand::rngs::SysRng;
+use rand_core::{Rng as _, UnwrapErr};
+
+use crate::{
+    actors::vault::{self, Bootstrap, TryUnseal, Vault},
+    crypto::{KeyCell, derive_key, encryption::v1::Nonce, shamir},
+    db::{
+        self,
+        custody::{self, CustodyRecord, EncryptedShare},
+        models::OperatorId,
+    },
+};
+
+const SHARE_AAD: &[u8] = b"arbiter/shamir-share/v1";
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("An ordinary committee is already being coordinated")]
+    AlreadyBootstrapping,
+    #[error("An unseal is already being coordinated")]
+    AlreadyUnsealing,
+    #[error("Bootstrap is not in progress")]
+    NotBootstrapping,
+    #[error("The operator already contributed")]
+    DuplicateContribution,
+    #[error("The ordinary committee cannot be empty")]
+    EmptyCommittee,
+    #[error("Two-operator committees are unsupported")]
+    UnsupportedCommittee,
+    #[error(
+        "The ordinary committee cannot exceed {} members",
+        shamir::MAX_COMMITTEE_SIZE
+    )]
+    CommitteeTooLarge,
+    #[error("Invalid passphrase")]
+    InvalidPassphrase,
+    #[error("Broken database")]
+    BrokenDatabase,
+    #[error("Shamir error: {0}")]
+    Shamir(String),
+    #[error("Database connection error: {0}")]
+    DatabaseConnection(#[from] db::PoolError),
+    #[error("Custody storage error: {0}")]
+    Custody(#[from] custody::Error),
+    #[error("Encryption error")]
+    Encryption,
+    #[error("The vault is already bootstrapped")]
+    AlreadyBootstrapped,
+    #[error("Vault error")]
+    Vault,
+}
+
+/// Passphrases gathered so far, in contribution order.
+///
+/// A `Vec` rather than a map because [`SafeCell`] values are neither cloneable
+/// nor hashable, and a committee holds at most
+/// [`shamir::MAX_COMMITTEE_SIZE`] of them.
+#[derive(Default)]
+struct Contributions(Vec<(OperatorId, SafeCell<Vec<u8>>)>);
+
+impl Contributions {
+    fn contains(&self, operator_id: OperatorId) -> bool {
+        self.0.iter().any(|(id, _)| *id == operator_id)
+    }
+
+    fn put(&mut self, operator_id: OperatorId, passphrase: SafeCell<Vec<u8>>) {
+        match self.0.iter_mut().find(|(id, _)| *id == operator_id) {
+            Some(slot) => slot.1 = passphrase,
+            None => self.0.push((operator_id, passphrase)),
+        }
+    }
+
+    const fn len(&self) -> usize {
+        self.0.len()
+    }
+
+    fn operators(&self) -> Vec<OperatorId> {
+        self.0.iter().map(|(id, _)| *id).collect()
+    }
+}
+
+enum CoordinatorState {
+    Idle,
+    Bootstrapping {
+        /// The operator that declared the committee. Only they may re-declare
+        /// it, which is the way out of a ceremony the others never finish.
+        declarer: OperatorId,
+        declared_count: usize,
+        contributions: Contributions,
+        retryable: bool,
+    },
+    Unsealing {
+        threshold: usize,
+        contributions: Contributions,
+        retryable: bool,
+    },
+}
+
+#[derive(Actor)]
+pub struct VaultCoordinator {
+    db: db::DatabasePool,
+    vault: ActorRef<Vault>,
+    state: CoordinatorState,
+}
+
+impl VaultCoordinator {
+    pub const fn new(db: db::DatabasePool, vault: ActorRef<Vault>) -> Self {
+        Self {
+            db,
+            vault,
+            state: CoordinatorState::Idle,
+        }
+    }
+}
+
+/// Explain why a committee size was rejected.
+const fn committee_error(declared_count: usize) -> Error {
+    match declared_count {
+        0 => Error::EmptyCommittee,
+        2 => Error::UnsupportedCommittee,
+        _ => Error::CommitteeTooLarge,
+    }
+}
+
+fn encrypt_share(
+    passphrase: &mut SafeCell<Vec<u8>>,
+    share: &[u8],
+) -> Result<EncryptedShare, Error> {
+    let mut salt = [0u8; RECOMMENDED_SALT_LEN];
+    UnwrapErr(SysRng).fill_bytes(&mut salt);
+
+    let nonce = Nonce::default();
+    let ciphertext = derive_key(passphrase, &salt)
+        .encrypt(&nonce, SHARE_AAD, share)
+        .map_err(|_| Error::Encryption)?;
+
+    Ok(EncryptedShare {
+        ciphertext,
+        nonce: nonce.to_vec(),
+        salt: salt.to_vec(),
+    })
+}
+
+fn decrypt_share(
+    passphrase: &mut SafeCell<Vec<u8>>,
+    share: EncryptedShare,
+) -> Result<SafeCell<Vec<u8>>, Error> {
+    let nonce = Nonce::try_from(share.nonce.as_slice()).map_err(|()| Error::BrokenDatabase)?;
+
+    let mut buffer = SafeCell::new(share.ciphertext);
+    derive_key(passphrase, &share.salt)
+        .decrypt_in_place(&nonce, SHARE_AAD, &mut buffer)
+        .map_err(|_| Error::InvalidPassphrase)?;
+
+    Ok(buffer)
+}
+
+const fn bootstrap_error(error: &SendError<Bootstrap, vault::Error>) -> Error {
+    match error {
+        SendError::HandlerError(vault::Error::AlreadyBootstrapped) => Error::AlreadyBootstrapped,
+        _ => Error::Vault,
+    }
+}
+
+/// Build the custody record and hand it to the vault, which stores it in the
+/// same transaction as the root key.
+async fn finalize_bootstrap(
+    vault: &ActorRef<Vault>,
+    contributions: &mut Contributions,
+) -> Result<(), Error> {
+    let total = contributions.len();
+    let threshold = shamir::shamir_threshold(total).ok_or_else(|| committee_error(total))?;
+
+    let mut seal_key = KeyCell::new_secure_random();
+    let mut shares = shamir::split_key(threshold, total, &mut seal_key, UnwrapErr(SysRng))
+        .map_err(|error| Error::Shamir(error.to_string()))?;
+
+    if shares.len() < total {
+        return Err(Error::Shamir("missing share for operator".to_owned()));
+    }
+
+    let mut encrypted = Vec::with_capacity(total);
+    for ((operator_id, passphrase), share) in contributions.0.iter_mut().zip(shares.iter_mut()) {
+        let share = share.read_inline(|share| encrypt_share(passphrase, share))?;
+        encrypted.push((*operator_id, share));
+    }
+
+    vault
+        .ask(Bootstrap {
+            seal_key,
+            custody: Some(CustodyRecord {
+                threshold,
+                shares: encrypted,
+            }),
+        })
+        .await
+        .map_err(|error| bootstrap_error(&error))
+}
+
+/// Reconstruct the seal key from the contributed passphrases and unseal.
+async fn finalize_unseal(
+    db: &db::DatabasePool,
+    vault: &ActorRef<Vault>,
+    threshold: usize,
+    contributions: &mut Contributions,
+) -> Result<(), Error> {
+    let stored = {
+        let mut conn = db.get().await?;
+        custody::shares(&mut conn, &contributions.operators()).await?
+    };
+
+    let mut plaintext = Vec::with_capacity(stored.len());
+    for ((_, passphrase), share) in contributions.0.iter_mut().zip(stored) {
+        plaintext.push(decrypt_share(passphrase, share)?);
+    }
+
+    let seal_key = shamir::combine_shares(threshold, &mut plaintext)
+        .map_err(|error| Error::Shamir(error.to_string()))?;
+
+    vault
+        .ask(TryUnseal { seal_key })
+        .await
+        .map_err(|_| Error::Vault)
+}
+
+#[messages]
+impl VaultCoordinator {
+    /// Announce how many operators will contribute to the bootstrap.
+    ///
+    /// The declaring operator may re-declare to restart the ceremony; that is
+    /// the only way to release a committee whose members never all show up.
+    #[message]
+    pub fn start_bootstrap(
+        &mut self,
+        operator_id: OperatorId,
+        declared_count: usize,
+    ) -> Result<(), Error> {
+        if shamir::shamir_threshold(declared_count).is_none() {
+            return Err(committee_error(declared_count));
+        }
+
+        match &self.state {
+            CoordinatorState::Unsealing { .. } => return Err(Error::AlreadyUnsealing),
+            CoordinatorState::Bootstrapping { declarer, .. } if *declarer != operator_id => {
+                return Err(Error::AlreadyBootstrapping);
+            }
+            CoordinatorState::Bootstrapping { .. } | CoordinatorState::Idle => {}
+        }
+
+        self.state = CoordinatorState::Bootstrapping {
+            declarer: operator_id,
+            declared_count,
+            contributions: Contributions::default(),
+            retryable: false,
+        };
+        Ok(())
+    }
+
+    #[message]
+    pub async fn contribute_bootstrap(
+        &mut self,
+        operator_id: OperatorId,
+        passphrase: SafeCell<Vec<u8>>,
+    ) -> Result<bool, Error> {
+        let CoordinatorState::Bootstrapping {
+            declared_count,
+            contributions,
+            retryable,
+            ..
+        } = &mut self.state
+        else {
+            return Err(Error::NotBootstrapping);
+        };
+
+        if contributions.contains(operator_id) && !*retryable {
+            return Err(Error::DuplicateContribution);
+        }
+        contributions.put(operator_id, passphrase);
+        *retryable = false;
+
+        if contributions.len() < *declared_count {
+            return Ok(false);
+        }
+
+        let state = std::mem::replace(&mut self.state, CoordinatorState::Idle);
+        let CoordinatorState::Bootstrapping {
+            declarer,
+            declared_count,
+            mut contributions,
+            ..
+        } = state
+        else {
+            unreachable!("state was matched as Bootstrapping above")
+        };
+
+        match finalize_bootstrap(&self.vault, &mut contributions).await {
+            Ok(()) => Ok(true),
+            Err(error) => {
+                self.state = CoordinatorState::Bootstrapping {
+                    declarer,
+                    declared_count,
+                    contributions,
+                    retryable: true,
+                };
+                Err(error)
+            }
+        }
+    }
+
+    #[message]
+    pub async fn contribute_unseal(
+        &mut self,
+        operator_id: OperatorId,
+        passphrase: SafeCell<Vec<u8>>,
+    ) -> Result<bool, Error> {
+        if matches!(self.state, CoordinatorState::Idle) {
+            let threshold = {
+                let mut conn = self.db.get().await?;
+                custody::threshold(&mut conn).await?
+            };
+            self.state = CoordinatorState::Unsealing {
+                threshold,
+                contributions: Contributions::default(),
+                retryable: false,
+            };
+        }
+
+        let CoordinatorState::Unsealing {
+            threshold,
+            contributions,
+            retryable,
+        } = &mut self.state
+        else {
+            return Err(Error::AlreadyBootstrapping);
+        };
+
+        if contributions.contains(operator_id) && !*retryable {
+            return Err(Error::DuplicateContribution);
+        }
+        contributions.put(operator_id, passphrase);
+        *retryable = false;
+
+        if contributions.len() < *threshold {
+            return Ok(false);
+        }
+
+        let state = std::mem::replace(&mut self.state, CoordinatorState::Idle);
+        let CoordinatorState::Unsealing {
+            threshold,
+            mut contributions,
+            ..
+        } = state
+        else {
+            unreachable!("state was matched as Unsealing above")
+        };
+
+        match finalize_unseal(&self.db, &self.vault, threshold, &mut contributions).await {
+            Ok(()) => Ok(true),
+            Err(error) => {
+                self.state = CoordinatorState::Unsealing {
+                    threshold,
+                    contributions,
+                    retryable: true,
+                };
+                Err(error)
+            }
+        }
+    }
+}

server/crates/arbiter-server/src/crypto/encryption/v1.rs

@@ -1,3 +1,4 @@
+use argon2::password_hash::Salt as ArgonSalt;
 use rand::{
     Rng as _, SeedableRng,
     rngs::{StdRng, SysRng},
@@ -41,7 +42,7 @@ impl<'a> TryFrom<&'a [u8]> for Nonce {
     }
 }
 
-pub type Salt = [u8; argon2::RECOMMENDED_SALT_LEN];
+pub type Salt = [u8; ArgonSalt::RECOMMENDED_LENGTH];
 
 pub fn generate_salt() -> Salt {
     let mut salt = Salt::default();
@@ -60,12 +61,11 @@ mod tests {
     #[test]
     fn derive_seal_key_deterministic() {
         static PASSWORD: &[u8] = b"password";
-        let password = SafeCell::new(PASSWORD.to_vec());
-        let password2 = SafeCell::new(PASSWORD.to_vec());
+        let mut password = SafeCell::new(PASSWORD.to_vec());
         let salt = generate_salt();
 
-        let mut key1 = derive_key(password, &salt);
-        let mut key2 = derive_key(password2, &salt);
+        let mut key1 = derive_key(&mut password, &salt);
+        let mut key2 = derive_key(&mut password, &salt);
 
         let key1_reader = key1.0.read();
         let key2_reader = key2.0.read();
@@ -76,10 +76,10 @@ mod tests {
     #[test]
     fn successful_derive() {
         static PASSWORD: &[u8] = b"password";
-        let password = SafeCell::new(PASSWORD.to_vec());
+        let mut password = SafeCell::new(PASSWORD.to_vec());
         let salt = generate_salt();
 
-        let mut key = derive_key(password, &salt);
+        let mut key = derive_key(&mut password, &salt);
         let key_reader = key.0.read();
 
         assert_ne!(key_reader.as_slice(), &[0u8; 32][..]);

server/crates/arbiter-server/src/crypto/integrity/v1.rs

@@ -215,9 +215,9 @@ mod tests {
             GlobalActors,
             vault::{Bootstrap, Vault},
         },
+        crypto::KeyCell,
         db::{self, schema},
     };
-    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 
     use super::{Error, Integrable, sign_entity, verify_entity};
     #[derive(Clone, arbiter_macros::Hashable)]
@@ -237,7 +237,8 @@ mod tests {
         );
         actor
             .ask(Bootstrap {
-                seal_key_raw: SafeCell::new(b"integrity-test-seal-key".to_vec()),
+                seal_key: KeyCell::from([0u8; 32]),
+                custody: None,
             })
             .await
             .unwrap();

server/crates/arbiter-server/src/crypto/mod.rs

@@ -1,10 +1,10 @@
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
-use encryption::v1::{Nonce, Salt};
+use encryption::v1::Nonce;
 
 use argon2::{Algorithm, Argon2};
 use chacha20poly1305::{
-    AeadInOut, Key, KeyInit as _, XChaCha20Poly1305, XNonce,
-    aead::{Aead, Error, Payload},
+    AeadInPlace, Key, KeyInit as _, XChaCha20Poly1305, XNonce,
+    aead::{AeadMut, Error, Payload},
 };
 use rand::{
     Rng as _, SeedableRng as _,
@@ -13,6 +13,7 @@ use rand::{
 
 pub mod encryption;
 pub mod integrity;
+pub mod shamir;
 
 pub struct KeyCell(pub SafeCell<Key>);
 impl From<SafeCell<Key>> for KeyCell {
@@ -20,6 +21,16 @@ impl From<SafeCell<Key>> for KeyCell {
         Self(value)
     }
 }
+
+impl From<[u8; 32]> for KeyCell {
+    fn from(bytes: [u8; 32]) -> Self {
+        let cell = SafeCell::new_inline(|key: &mut Key| {
+            key.copy_from_slice(&bytes);
+        });
+        Self(cell)
+    }
+}
+
 impl TryFrom<SafeCell<Vec<u8>>> for KeyCell {
     type Error = ();
 
@@ -54,10 +65,11 @@ impl KeyCell {
     ) -> Result<(), Error> {
         let key_reader = self.0.read();
         let cipher = XChaCha20Poly1305::new(&key_reader);
-        let nonce = XNonce::from(nonce.0);
+        let nonce = XNonce::from_slice(nonce.0.as_ref());
         let buffer = buffer.as_mut();
-        cipher.encrypt_in_place(&nonce, associated_data, buffer)
+        cipher.encrypt_in_place(nonce, associated_data, buffer)
     }
+
     pub fn decrypt_in_place(
         &mut self,
         nonce: &Nonce,
@@ -66,10 +78,10 @@ impl KeyCell {
     ) -> Result<(), Error> {
         let key_reader = self.0.read();
         let cipher = XChaCha20Poly1305::new(&key_reader);
-        let nonce = XNonce::from(nonce.0);
+        let nonce = XNonce::from_slice(nonce.0.as_ref());
         let mut buffer = buffer.write();
         let buffer: &mut Vec<u8> = buffer.as_mut();
-        cipher.decrypt_in_place(&nonce, associated_data, buffer)
+        cipher.decrypt_in_place(nonce, associated_data, buffer)
     }
 
     pub fn encrypt(
@@ -79,11 +91,11 @@ impl KeyCell {
         plaintext: impl AsRef<[u8]>,
     ) -> Result<Vec<u8>, Error> {
         let key_reader = self.0.read();
-        let cipher = XChaCha20Poly1305::new(&key_reader);
-        let nonce = XNonce::from(nonce.0);
+        let mut cipher = XChaCha20Poly1305::new(&key_reader);
+        let nonce = XNonce::from_slice(nonce.0.as_ref());
 
         let ciphertext = cipher.encrypt(
-            &nonce,
+            nonce,
             Payload {
                 msg: plaintext.as_ref(),
                 aad: associated_data,
@@ -93,8 +105,11 @@ impl KeyCell {
     }
 }
 
-/// Derive a fixed-length key from the password using Argon2id, which is designed for password hashing and key derivation.
-pub fn derive_key(mut password: SafeCell<Vec<u8>>, salt: &Salt) -> KeyCell {
+/// Derive a fixed-length key from a passphrase using Argon2id.
+///
+/// The passphrase is borrowed so that callers can keep it in protected memory
+/// and reuse it across retries instead of handing over a copy.
+pub fn derive_key(password: &mut SafeCell<Vec<u8>>, salt: &[u8]) -> KeyCell {
     let params = {
         #[cfg(debug_assertions)]
         {
@@ -132,11 +147,11 @@ mod tests {
     #[test]
     fn encrypt_decrypt() {
         static PASSWORD: &[u8] = b"password";
-        let password = SafeCell::new(PASSWORD.to_vec());
+        let mut password = SafeCell::new(PASSWORD.to_vec());
         let salt = generate_salt();
 
-        let mut key = derive_key(password, &salt);
-        let nonce = Nonce(*b"unique nonce 123 1231233"); // 24 bytes for XChaCha20Poly1305
+        let mut key = derive_key(&mut password, &salt);
+        let nonce = Nonce(*b"unique nonce 123 1231233");
         let associated_data = b"associated data";
         let mut buffer = b"secret data".to_vec();
 

server/crates/arbiter-server/src/crypto/shamir.rs

@@ -0,0 +1,221 @@
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use rand_core::CryptoRng;
+use vsss_rs::Gf256;
+
+use crate::crypto::KeyCell;
+
+/// GF(256) addresses shares by a non-zero byte, so no committee can exceed 255.
+pub const MAX_COMMITTEE_SIZE: usize = 255;
+
+/// Errors returned by Shamir split/combine operations.
+#[derive(Debug, thiserror::Error)]
+pub enum ShamirError {
+    #[error("failed to split key: {0}")]
+    Split(String),
+    #[error("failed to combine shares: {0}")]
+    Combine(String),
+}
+
+/// Return the required threshold for a Shamir share pool of `committee_size`.
+///
+/// A pool of two is rejected: a majority of two is two, which gives each holder
+/// a veto over every unseal without giving either one recovery. That rejects no
+/// supported committee, because a two-operator vault must carry at least one
+/// recovery share and so never splits into a pool of two -- see
+/// `docs/ARCHITECTURE.md` 3.9.
+#[expect(
+    clippy::integer_division,
+    reason = "majority thresholds use integer arithmetic"
+)]
+#[must_use]
+pub const fn shamir_threshold(committee_size: usize) -> Option<usize> {
+    match committee_size {
+        0 | 2 => None,
+        size if size > MAX_COMMITTEE_SIZE => None,
+        1 => Some(1),
+        size => Some(size / 2 + 1),
+    }
+}
+
+/// Split a seal key into `total` shares, `threshold` of which reconstruct it.
+pub fn split_key(
+    threshold: usize,
+    total: usize,
+    key: &mut KeyCell,
+    rng: impl CryptoRng,
+) -> Result<Vec<SafeCell<Vec<u8>>>, ShamirError> {
+    if total == 0 || threshold == 0 || threshold > total || total == 2 || total > MAX_COMMITTEE_SIZE
+    {
+        return Err(ShamirError::Split(
+            "unsupported committee parameters".to_owned(),
+        ));
+    }
+
+    // Nothing to interpolate when one share suffices.
+    if threshold == 1 {
+        return Ok(key.0.read_inline(|key| {
+            std::iter::repeat_with(|| SafeCell::new(key.as_slice().to_vec()))
+                .take(total)
+                .collect()
+        }));
+    }
+
+    key.0.read_inline(|key| {
+        let key: &[u8; 32] = key
+            .as_slice()
+            .try_into()
+            .map_err(|_| ShamirError::Split("unexpected seal key length".to_owned()))?;
+
+        Gf256::split_array(threshold, total, key, rng)
+            .map(|shares| shares.into_iter().map(SafeCell::new).collect())
+            .map_err(|error| ShamirError::Split(format!("{error:?}")))
+    })
+}
+
+/// Combine shares back into the seal key.
+///
+/// `threshold` comes from storage rather than from the shapes of the shares:
+/// a one-of-one committee stores the key verbatim, and telling that apart by
+/// share length alone would misread any Shamir share that happened to be key
+/// sized.
+pub fn combine_shares(
+    threshold: usize,
+    shares: &mut [SafeCell<Vec<u8>>],
+) -> Result<KeyCell, ShamirError> {
+    if threshold == 0 {
+        return Err(ShamirError::Combine("threshold is zero".to_owned()));
+    }
+    if shares.len() < threshold {
+        return Err(ShamirError::Combine(
+            "not enough shares supplied".to_owned(),
+        ));
+    }
+
+    // Mirror of the one-of-one case in [`split_key`]: the share is the key.
+    if threshold == 1 {
+        let share = shares
+            .first_mut()
+            .ok_or_else(|| ShamirError::Combine("no shares supplied".to_owned()))?;
+        return reconstructed_key(share.read_inline(|share| SafeCell::new(share.clone())));
+    }
+
+    let mut gathered = SafeCell::new(Vec::with_capacity(shares.len()));
+    for share in shares.iter_mut() {
+        share.read_inline(|share| {
+            gathered.write_inline(|gathered| gathered.push(share.clone()));
+        });
+    }
+
+    let combined = gathered.read_inline(|gathered| {
+        Gf256::combine_array(gathered.as_slice())
+            .map(SafeCell::new)
+            .map_err(|error| ShamirError::Combine(format!("{error:?}")))
+    })?;
+
+    reconstructed_key(combined)
+}
+
+fn reconstructed_key(bytes: SafeCell<Vec<u8>>) -> Result<KeyCell, ShamirError> {
+    KeyCell::try_from(bytes)
+        .map_err(|()| ShamirError::Combine("unexpected reconstructed key length".to_owned()))
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{MAX_COMMITTEE_SIZE, combine_shares, shamir_threshold, split_key};
+    use crate::crypto::KeyCell;
+    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+    use rand::rngs::SysRng;
+    use rand_core::UnwrapErr;
+    use rstest::rstest;
+
+    fn key_bytes(mut key: KeyCell) -> [u8; 32] {
+        key.0.read_inline(|key| {
+            let mut bytes = [0u8; 32];
+            bytes.copy_from_slice(key.as_slice());
+            bytes
+        })
+    }
+
+    fn select(shares: &mut [SafeCell<Vec<u8>>], indexes: &[usize]) -> Vec<SafeCell<Vec<u8>>> {
+        indexes
+            .iter()
+            .filter_map(|index| {
+                shares
+                    .get_mut(*index)
+                    .map(|share| share.read_inline(|share| SafeCell::new(share.clone())))
+            })
+            .collect()
+    }
+
+    #[rstest]
+    #[case(&[0, 1])]
+    #[case(&[0, 2])]
+    #[case(&[1, 2])]
+    fn threshold_shares_reconstruct_fixed_key(#[case] indexes: &[usize]) {
+        let expected = [9_u8; 32];
+        let mut key = KeyCell::from(expected);
+        let rng = UnwrapErr(SysRng);
+        let mut shares = split_key(2, 3, &mut key, rng).expect("split should succeed");
+        let mut selected = select(&mut shares, indexes);
+        let combined = combine_shares(2, &mut selected).expect("combine should succeed");
+        assert_eq!(key_bytes(combined), expected);
+    }
+
+    #[test]
+    fn one_of_one_round_trips_a_fixed_size_key() {
+        let expected = [7_u8; 32];
+        let mut key = KeyCell::from(expected);
+        let rng = UnwrapErr(SysRng);
+        let mut shares = split_key(1, 1, &mut key, rng).expect("split should succeed");
+        let combined = combine_shares(1, &mut shares).expect("combine should succeed");
+        assert_eq!(key_bytes(combined), expected);
+    }
+
+    #[test]
+    fn fewer_shares_than_threshold_is_rejected() {
+        let mut key = KeyCell::from([3_u8; 32]);
+        let rng = UnwrapErr(SysRng);
+        let mut shares = split_key(3, 5, &mut key, rng).expect("split should succeed");
+        let mut selected = select(&mut shares, &[0, 1]);
+        assert!(
+            combine_shares(3, &mut selected).is_err(),
+            "two of three shares must not reconstruct the key"
+        );
+    }
+
+    #[rstest]
+    #[case(0, None)]
+    #[case(1, Some(1))]
+    #[case(2, None)]
+    #[case(3, Some(2))]
+    #[case(4, Some(3))]
+    #[case(MAX_COMMITTEE_SIZE, Some(128))]
+    #[case(MAX_COMMITTEE_SIZE + 1, None)]
+    fn committee_threshold_is_a_majority(
+        #[case] committee_size: usize,
+        #[case] expected: Option<usize>,
+    ) {
+        assert_eq!(shamir_threshold(committee_size), expected);
+    }
+
+    #[test]
+    fn oversized_committee_is_rejected_by_split() {
+        let mut key = KeyCell::from([1_u8; 32]);
+        let rng = UnwrapErr(SysRng);
+        assert!(
+            split_key(129, MAX_COMMITTEE_SIZE + 1, &mut key, rng).is_err(),
+            "committees above the GF(256) share limit must be rejected"
+        );
+    }
+
+    #[test]
+    fn two_operator_committee_is_explicitly_unsupported() {
+        let mut key = KeyCell::from([7_u8; 32]);
+        let rng = UnwrapErr(SysRng);
+        assert!(
+            split_key(2, 2, &mut key, rng).is_err(),
+            "two-operator committees must be rejected"
+        );
+    }
+}

server/crates/arbiter-server/src/db/custody.rs

@@ -0,0 +1,137 @@
+//! Storage for Shamir custody material: the reconstruction threshold and the
+//! per-operator encrypted shares of the vault seal key.
+//!
+//! The queries live here so that the actors above hold no Diesel code of their
+//! own. Every one of them borrows the caller's connection instead of taking one
+//! from the pool, which is what lets the vault write custody material inside
+//! the same transaction that stores the root key.
+
+use std::collections::HashMap;
+
+use diesel::{ExpressionMethods as _, QueryDsl};
+use diesel_async::RunQueryDsl;
+
+use crate::db::{
+    self,
+    models::{OperatorId, SqliteTimestamp},
+    schema,
+};
+
+/// One Shamir share, encrypted under a key derived from its operator's passphrase.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct EncryptedShare {
+    pub ciphertext: Vec<u8>,
+    pub nonce: Vec<u8>,
+    pub salt: Vec<u8>,
+}
+
+/// Everything a bootstrap persists about custody, written as a single unit.
+#[derive(Debug)]
+pub struct CustodyRecord {
+    pub threshold: usize,
+    pub shares: Vec<(OperatorId, EncryptedShare)>,
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("Database query error: {0}")]
+    Query(#[from] diesel::result::Error),
+    #[error("Stored committee threshold is missing or out of range")]
+    BrokenThreshold,
+    #[error("Custody settings row is missing")]
+    MissingSettings,
+    #[error("No share stored for operator {0:?}")]
+    MissingShare(OperatorId),
+}
+
+/// Persist threshold and shares on the caller's connection, joining any
+/// transaction the caller has already opened.
+pub async fn write_record(
+    conn: &mut db::DatabaseConnection,
+    record: &CustodyRecord,
+) -> Result<(), Error> {
+    let threshold = i32::try_from(record.threshold).map_err(|_| Error::BrokenThreshold)?;
+
+    // SQLite has no batch form for REPLACE INTO in diesel, so the rows go
+    // in one at a time. The caller's transaction still makes them atomic.
+    let now = SqliteTimestamp::now();
+    for (operator_id, share) in &record.shares {
+        diesel::replace_into(schema::operator::table)
+            .values((
+                schema::operator::id.eq(Some(*operator_id)),
+                schema::operator::share.eq(&share.ciphertext),
+                schema::operator::share_nonce.eq(&share.nonce),
+                schema::operator::share_salt.eq(&share.salt),
+                schema::operator::created_at.eq(now.clone()),
+                schema::operator::updated_at.eq(now.clone()),
+            ))
+            .execute(&mut *conn)
+            .await?;
+    }
+
+    let updated = diesel::update(schema::arbiter_settings::table)
+        .set(schema::arbiter_settings::shamir_threshold.eq(Some(threshold)))
+        .execute(&mut *conn)
+        .await?;
+    if updated != 1 {
+        return Err(Error::MissingSettings);
+    }
+
+    Ok(())
+}
+
+/// Number of shares required to reconstruct the seal key.
+pub async fn threshold(conn: &mut db::DatabaseConnection) -> Result<usize, Error> {
+    let stored: Option<i32> = schema::arbiter_settings::table
+        .select(schema::arbiter_settings::shamir_threshold)
+        .first(conn)
+        .await?;
+
+    stored
+        .and_then(|value| usize::try_from(value).ok())
+        .filter(|threshold| *threshold > 0)
+        .ok_or(Error::BrokenThreshold)
+}
+
+/// Load the shares of `operators` in one query, in the order requested.
+pub async fn shares(
+    conn: &mut db::DatabaseConnection,
+    operators: &[OperatorId],
+) -> Result<Vec<EncryptedShare>, Error> {
+    /// (id, then the three columns that make up [`EncryptedShare`])
+    type ShareRow = (Option<OperatorId>, Vec<u8>, Vec<u8>, Vec<u8>);
+
+    let wanted: Vec<Option<OperatorId>> = operators.iter().copied().map(Some).collect();
+
+    let rows: Vec<ShareRow> = schema::operator::table
+        .filter(schema::operator::id.eq_any(wanted))
+        .select((
+            schema::operator::id,
+            schema::operator::share,
+            schema::operator::share_nonce,
+            schema::operator::share_salt,
+        ))
+        .load(conn)
+        .await?;
+
+    let mut found: HashMap<OperatorId, EncryptedShare> = rows
+        .into_iter()
+        .filter_map(|(id, ciphertext, nonce, salt)| {
+            id.map(|id| {
+                (
+                    id,
+                    EncryptedShare {
+                        ciphertext,
+                        nonce,
+                        salt,
+                    },
+                )
+            })
+        })
+        .collect();
+
+    operators
+        .iter()
+        .map(|id| found.remove(id).ok_or(Error::MissingShare(*id)))
+        .collect()
+}

server/crates/arbiter-server/src/db/mod.rs

@@ -8,6 +8,7 @@ use diesel_migrations::{EmbeddedMigrations, MigrationHarness, embed_migrations};
 use thiserror::Error;
 use tracing::info;
 
+pub mod custody;
 pub mod models;
 pub mod schema;
 
@@ -154,3 +155,39 @@ pub async fn create_test_pool() -> DatabasePool {
         .await
         .expect("Failed to create test database pool")
 }
+
+#[cfg(test)]
+mod tests {
+    use diesel::{ExpressionMethods as _, result::DatabaseErrorKind};
+    use diesel_async::RunQueryDsl as _;
+
+    use super::*;
+
+    #[tokio::test]
+    async fn operator_share_salt_must_be_supplied_by_application() {
+        let pool = create_test_pool().await;
+        let mut conn = pool.get().await.expect("pool connection");
+
+        let operator_id = diesel::insert_into(schema::operator_identity::table)
+            .values(schema::operator_identity::public_key.eq(vec![1]))
+            .returning(schema::operator_identity::id)
+            .get_result::<i32>(&mut conn)
+            .await
+            .expect("insert operator identity");
+
+        let error = diesel::insert_into(schema::operator::table)
+            .values((
+                schema::operator::id.eq(operator_id),
+                schema::operator::share.eq(vec![2]),
+                schema::operator::share_nonce.eq(vec![3]),
+            ))
+            .execute(&mut conn)
+            .await
+            .expect_err("operator insert without an application-generated salt must fail");
+
+        assert!(matches!(
+            error,
+            diesel::result::Error::DatabaseError(DatabaseErrorKind::NotNullViolation, _)
+        ));
+    }
+}

server/crates/arbiter-server/src/db/models.rs

@@ -110,6 +110,18 @@ pub mod types {
                     ToSql::<Integer, Sqlite>::to_sql(&self.0, out)
                 }
             }
+
+            impl arbiter_crypto::hashing::Hashable for $name {
+                fn hash<H: arbiter_crypto::hashing::Digest>(&self, hasher: &mut H) {
+                    arbiter_crypto::hashing::Hashable::hash(&self.0, hasher);
+                }
+            }
+
+            impl crate::crypto::integrity::v1::IntoId for $name {
+                fn into_id(self) -> Vec<u8> {
+                    crate::crypto::integrity::v1::IntoId::into_id(self.0)
+                }
+            }
         };
     }
 
@@ -203,6 +215,7 @@ pub struct ArbiterSettings {
     pub id: i32,
     pub root_key_id: Option<i32>, // references root_key_history.id
     pub tls_id: Option<i32>,      // references tls_history.id
+    pub shamir_threshold: Option<i32>,
 }
 
 #[derive(Models, Queryable, Debug, Insertable, Selectable)]
@@ -285,6 +298,7 @@ pub struct Operator {
     pub id: OperatorId,
     pub share: Vec<u8>,
     pub share_nonce: Vec<u8>,
+    pub share_salt: Vec<u8>,
     pub created_at: SqliteTimestamp,
     pub updated_at: SqliteTimestamp,
 }

server/crates/arbiter-server/src/db/schema.rs

@@ -17,6 +17,7 @@ diesel::table! {
         id -> Integer,
         root_key_id -> Nullable<Integer>,
         tls_id -> Nullable<Integer>,
+        shamir_threshold -> Nullable<Integer>,
     }
 }
 
@@ -157,6 +158,7 @@ diesel::table! {
         id -> Nullable<Integer>,
         share -> Binary,
         share_nonce -> Binary,
+        share_salt -> Binary,
         created_at -> Integer,
         updated_at -> Integer,
     }

server/crates/arbiter-server/src/evm/mod.rs

@@ -502,7 +502,6 @@ impl Engine {
 #[cfg(test)]
 mod tests {
     use alloy::primitives::{Address, Bytes, U256, address};
-    use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
     use chrono::{Duration, Utc};
     use diesel::{SelectableHelper, insert_into};
     use diesel_async::RunQueryDsl;
@@ -510,6 +509,7 @@ mod tests {
     use rstest::rstest;
 
     use crate::actors::{GlobalActors, vault::{Bootstrap, Vault}};
+    use crate::crypto::KeyCell;
     use crate::crypto::integrity;
     use crate::db::{
         self, DatabaseConnection,
@@ -772,7 +772,8 @@ mod tests {
         );
         actor
             .ask(Bootstrap {
-                seal_key_raw: SafeCell::new(b"integrity-test-seal-key".to_vec()),
+                seal_key: KeyCell::from([0u8; 32]),
+                custody: None,
             })
             .await
             .unwrap();

server/crates/arbiter-server/src/grpc/operator.rs

@@ -1,11 +1,10 @@
 use crate::{
     grpc::request_tracker::RequestTracker,
-    peers::operator::{OutOfBand, OperatorConnection, OperatorSession},
+    peers::operator::{OperatorConnection, OperatorSession, OutOfBand},
 };
 use arbiter_proto::{
     proto::operator::{
-        OperatorRequest, OperatorResponse,
-        operator_request::Payload as OperatorRequestPayload,
+        OperatorRequest, OperatorResponse, operator_request::Payload as OperatorRequestPayload,
         operator_response::Payload as OperatorResponsePayload,
     },
     transport::{Error as TransportError, Receiver, Sender, grpc::GrpcBi},
@@ -111,6 +110,9 @@ async fn dispatch_inner(
         OperatorRequestPayload::Vault(req) => vault::dispatch(actor, req).await,
         OperatorRequestPayload::Evm(req) => evm::dispatch(actor, req).await,
         OperatorRequestPayload::SdkClient(req) => sdk_client::dispatch(actor, req).await,
+        OperatorRequestPayload::Governance(_) => {
+            Err(Status::permission_denied(stringify!(Governance)))
+        }
         OperatorRequestPayload::Auth(..) => {
             warn!("Unsupported post-auth operator auth request");
             Err(Status::invalid_argument("Unsupported operator request"))

server/crates/arbiter-server/src/grpc/operator/vault.rs

@@ -3,7 +3,6 @@ use crate::{
     peers::operator::{OperatorSession, session::handlers::HandleQueryVaultState},
 };
 use arbiter_proto::{
-    proto::shared::VaultState as ProtoVaultState,
     proto::operator::{
         operator_response::Payload as OperatorResponsePayload,
         vault::{
@@ -11,6 +10,7 @@ use arbiter_proto::{
             response::Payload as VaultResponsePayload,
         },
     },
+    proto::shared::VaultState as ProtoVaultState,
 };
 
 use kameo::actor::ActorRef;
@@ -33,11 +33,11 @@ pub(super) async fn dispatch(
 
     match payload {
         VaultRequestPayload::QueryState(()) => handle_query_vault_state(actor).await,
-        VaultRequestPayload::Unseal(_) | VaultRequestPayload::Bootstrap(_) => {
-            Err(Status::permission_denied(
-                "Vault is already unsealed; unseal/bootstrap not permitted in session",
-            ))
-        }
+        VaultRequestPayload::Unseal(_)
+        | VaultRequestPayload::Bootstrap(_)
+        | VaultRequestPayload::Rekey(_) => Err(Status::permission_denied(
+            "Vault is already unsealed; unseal/bootstrap not permitted in session",
+        )),
     }
 }
 

server/crates/arbiter-server/src/grpc/operator/vault_gate/inbound.rs

@@ -1,14 +1,17 @@
 use crate::{
+    crypto::shamir,
     grpc::{Convert, TryConvert},
     peers::operator::vault_gate::{
-        self as vault_gate, HandleBootstrapEncryptedKey, HandleHandshake, HandleUnsealEncryptedKey,
+        self as vault_gate, HandleBootstrapEncryptedKey, HandleContributeBootstrapPassphrase,
+        HandleContributeUnsealPassphrase, HandleDeclareCommittee, HandleHandshake,
+        HandleUnsealEncryptedKey,
     },
 };
 use arbiter_proto::proto::operator::{
     operator_request::Payload as OperatorRequestPayload,
     vault::{
         self as proto_vault,
-        bootstrap::{self as proto_bootstrap},
+        bootstrap::{self as proto_bootstrap, request::Payload as BootstrapRequestPayload},
         request::Payload as VaultRequestPayload,
         unseal::{self as proto_unseal, request::Payload as UnsealRequestPayload},
     },
@@ -50,6 +53,7 @@ impl TryConvert for VaultRequestPayload {
             Self::QueryState(()) => Ok(vault_gate::Inbound::HandleVaultState),
             Self::Unseal(req) => req.try_convert(),
             Self::Bootstrap(req) => req.try_convert(),
+            Self::Rekey(_) => Err(Status::unimplemented("Vault re-key is not available")),
         }
     }
 }
@@ -73,6 +77,16 @@ impl TryConvert for UnsealRequestPayload {
         match self {
             Self::Start(start) => start.try_convert(),
             Self::EncryptedKey(key) => Ok(key.convert()),
+            Self::ContributePassphrase(passphrase) => {
+                Ok(vault_gate::Inbound::HandleContributeUnsealPassphrase(
+                    HandleContributeUnsealPassphrase {
+                        passphrase: passphrase.passphrase,
+                    },
+                ))
+            }
+            Self::ContributeRecoveryPassphrase(_) => Err(Status::unimplemented(
+                "Recovery operator contributions are not available",
+            )),
         }
     }
 }
@@ -107,12 +121,52 @@ impl TryConvert for proto_bootstrap::Request {
     type Error = Status;
 
     fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
-        self.encrypted_key
-            .ok_or_else(|| Status::invalid_argument("Missing bootstrap encrypted key"))?
+        self.payload
+            .ok_or_else(|| Status::invalid_argument("Missing bootstrap payload"))?
             .try_convert()
     }
 }
 
+impl TryConvert for BootstrapRequestPayload {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        match self {
+            Self::EncryptedKey(key) => key.try_convert(),
+            Self::DeclareCommittee(dc) => {
+                if dc.recovery_count != 0 {
+                    return Err(Status::unimplemented(
+                        "Recovery operator contributions are not available",
+                    ));
+                }
+                let count = usize::try_from(dc.count)
+                    .ok()
+                    .filter(|count| *count <= shamir::MAX_COMMITTEE_SIZE)
+                    .ok_or_else(|| {
+                        Status::invalid_argument(format!(
+                            "Committee count must not exceed {}",
+                            shamir::MAX_COMMITTEE_SIZE
+                        ))
+                    })?;
+                Ok(vault_gate::Inbound::HandleDeclareCommittee(
+                    HandleDeclareCommittee { count },
+                ))
+            }
+            Self::ContributePassphrase(cp) => {
+                Ok(vault_gate::Inbound::HandleContributeBootstrapPassphrase(
+                    HandleContributeBootstrapPassphrase {
+                        passphrase: cp.passphrase,
+                    },
+                ))
+            }
+            Self::ContributeRecoveryPassphrase(_) => Err(Status::unimplemented(
+                "Recovery operator contributions are not available",
+            )),
+        }
+    }
+}
+
 impl TryConvert for proto_bootstrap::BootstrapEncryptedKey {
     type Output = vault_gate::Inbound;
     type Error = Status;

server/crates/arbiter-server/src/grpc/operator/vault_gate/outbound.rs

@@ -1,10 +1,9 @@
 use crate::{
-    actors::vault::VaultState,
+    actors::{vault::VaultState, vault_coordinator},
     grpc::{Convert, TryConvert},
     peers::operator::vault_gate::{self as vault_gate},
 };
 use arbiter_proto::proto::{
-    shared::VaultState as ProtoVaultState,
     operator::{
         operator_response::Payload as OperatorResponsePayload,
         vault::{
@@ -17,6 +16,7 @@ use arbiter_proto::proto::{
             },
         },
     },
+    shared::VaultState as ProtoVaultState,
 };
 
 use tonic::Status;
@@ -34,6 +34,26 @@ const fn wrap_unseal_response(payload: UnsealResponsePayload) -> OperatorRespons
     }))
 }
 
+/// Ceremony errors are the operator's own doing far more often than ours, so
+/// they travel back as a specific status instead of a blanket internal error.
+fn ceremony_status(error: &vault_coordinator::Error) -> Status {
+    match error {
+        vault_coordinator::Error::AlreadyBootstrapping
+        | vault_coordinator::Error::AlreadyUnsealing
+        | vault_coordinator::Error::NotBootstrapping
+        | vault_coordinator::Error::DuplicateContribution => {
+            Status::failed_precondition(error.to_string())
+        }
+        vault_coordinator::Error::EmptyCommittee
+        | vault_coordinator::Error::UnsupportedCommittee
+        | vault_coordinator::Error::CommitteeTooLarge => {
+            Status::invalid_argument(error.to_string())
+        }
+        vault_coordinator::Error::InvalidPassphrase => Status::unauthenticated(error.to_string()),
+        _ => Status::internal("Vault ceremony failed"),
+    }
+}
+
 fn wrap_bootstrap_response(result: ProtoBootstrapResult) -> OperatorResponsePayload {
     wrap_vault_response(VaultResponsePayload::Bootstrap(proto_bootstrap::Response {
         result: result.into(),
@@ -87,7 +107,6 @@ impl TryConvert for vault_gate::Outbound {
                 let proto_result = match result {
                     Ok(()) => ProtoUnsealResult::Success,
                     Err(vault_gate::Error::InvalidKey) => ProtoUnsealResult::InvalidKey,
-                    Err(vault_gate::Error::LockedOut) => ProtoUnsealResult::LockedOut,
                     Err(err) => {
                         warn!(?err, "unseal failed");
                         return Err(Status::internal("Failed to unseal vault"));
@@ -111,6 +130,56 @@ impl TryConvert for vault_gate::Outbound {
                 };
                 Ok(wrap_bootstrap_response(proto_result))
             }
+            Self::HandleDeclareCommittee(result) => {
+                let proto_result = match result {
+                    Ok(()) => ProtoBootstrapResult::AwaitingContributions,
+                    Err(vault_gate::Error::Ceremony(
+                        vault_coordinator::Error::AlreadyBootstrapped,
+                    )) => ProtoBootstrapResult::AlreadyBootstrapped,
+                    Err(vault_gate::Error::Ceremony(err)) => {
+                        warn!(?err, "declare committee failed");
+                        return Err(ceremony_status(&err));
+                    }
+                    Err(err) => {
+                        warn!(?err, "declare committee failed");
+                        return Err(Status::internal("Failed to declare committee"));
+                    }
+                };
+                Ok(wrap_bootstrap_response(proto_result))
+            }
+            Self::HandleContributeBootstrapPassphrase(result) => {
+                let proto_result = match result {
+                    Ok(true) => ProtoBootstrapResult::Success,
+                    Ok(false) => ProtoBootstrapResult::AwaitingContributions,
+                    Err(vault_gate::Error::Ceremony(
+                        vault_coordinator::Error::AlreadyBootstrapped,
+                    )) => ProtoBootstrapResult::AlreadyBootstrapped,
+                    Err(vault_gate::Error::Ceremony(err)) => {
+                        warn!(?err, "contribute bootstrap passphrase failed");
+                        return Err(ceremony_status(&err));
+                    }
+                    Err(err) => {
+                        warn!(?err, "contribute bootstrap passphrase failed");
+                        return Err(Status::internal(
+                            "Failed to contribute bootstrap passphrase",
+                        ));
+                    }
+                };
+                Ok(wrap_bootstrap_response(proto_result))
+            }
+            Self::HandleContributeUnsealPassphrase(result) => {
+                let proto_result = match result {
+                    Ok(true) => ProtoUnsealResult::Success,
+                    Ok(false) => ProtoUnsealResult::AwaitingContributions,
+                    Err(err) => {
+                        warn!(?err, "contribute unseal passphrase failed");
+                        return Err(Status::internal("Failed to contribute unseal passphrase"));
+                    }
+                };
+                Ok(wrap_unseal_response(UnsealResponsePayload::Result(
+                    proto_result.into(),
+                )))
+            }
         }
     }
 }

server/crates/arbiter-server/src/peers/operator/auth/state.rs

@@ -3,8 +3,8 @@ use super::{
     Error,
 };
 use crate::{
-    actors::bootstrap::ConsumeToken,
-    db::{DatabasePool, schema::operator_identity},
+    actors::bootstrap::VerifyToken,
+    db::{DatabasePool, models::OperatorId, schema::operator_identity},
     peers::operator::auth::Outbound,
 };
 use arbiter_crypto::authn::{self, AuthChallenge, OPERATOR_CONTEXT};
@@ -37,7 +37,10 @@ smlang::statemachine!(
     }
 );
 
-async fn get_client_id(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<Option<i32>, Error> {
+async fn get_client_id(
+    db: &DatabasePool,
+    pubkey: &authn::PublicKey,
+) -> Result<Option<OperatorId>, Error> {
     let mut conn = db.get().await.map_err(|e| {
         error!(error = ?e, "Database pool error");
         Error::internal("Database unavailable")
@@ -46,7 +49,7 @@ async fn get_client_id(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<O
     operator_identity::table
         .filter(operator_identity::public_key.eq(pubkey.to_bytes()))
         .select(operator_identity::id)
-        .first::<i32>(&mut conn)
+        .first::<OperatorId>(&mut conn)
         .await
         .optional()
         .map_err(|e| {
@@ -55,14 +58,14 @@ async fn get_client_id(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<O
         })
 }
 
-async fn register_key(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<i32, Error> {
+async fn register_key(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<OperatorId, Error> {
     let pubkey_bytes = pubkey.to_bytes();
     let mut conn = db.get().await.map_err(|e| {
         error!(error = ?e, "Database pool error");
         Error::internal("Database unavailable")
     })?;
 
-    let id: i32 = diesel::insert_into(operator_identity::table)
+    let id: OperatorId = diesel::insert_into(operator_identity::table)
         .values((operator_identity::public_key.eq(pubkey_bytes),))
         .returning(operator_identity::id)
         .get_result(&mut conn)
@@ -156,7 +159,7 @@ where
                     .conn
                     .actors
                     .bootstrapper
-                    .ask(ConsumeToken { token })
+                    .ask(VerifyToken { token })
                     .await
                     .map_err(|e| {
                         error!(?e, "Failed to consume bootstrap token");

server/crates/arbiter-server/src/peers/operator/mod.rs

@@ -4,7 +4,7 @@ use crate::{
         vault::{GetState, Vault},
     },
     crypto::integrity::{self, AttestationStatus, Integrable},
-    db::{DatabaseError, DatabasePool},
+    db::{DatabaseError, DatabasePool, models::OperatorId},
     peers::client::ClientProfile,
 };
 use arbiter_crypto::authn;
@@ -25,7 +25,7 @@ pub mod vault_gate;
 
 #[derive(Debug, Clone, Hashable)]
 pub struct Credentials {
-    pub id: i32,
+    pub id: OperatorId,
     pub pubkey: authn::PublicKey,
 }
 

server/crates/arbiter-server/src/peers/operator/vault_gate/mod.rs

@@ -3,14 +3,15 @@ use crate::{
     actors::{
         GlobalActors,
         vault::{self, Bootstrap, GetState, TryUnseal, VaultState, events},
+        vault_coordinator::{self, ContributeBootstrap, ContributeUnseal, StartBootstrap},
     },
-    crypto::integrity::{self},
+    crypto::{KeyCell, integrity},
     db::DatabasePool,
 };
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use state::State;
 
-use chacha20poly1305::{AeadInOut, KeyInit as _, XChaCha20Poly1305, XNonce};
+use chacha20poly1305::{AeadInPlace, KeyInit as _, XChaCha20Poly1305, XNonce};
 use kameo::{Actor, error::SendError, messages, prelude::Message};
 use kameo_actors::message_bus::Register;
 use tokio::sync::oneshot;
@@ -27,17 +28,27 @@ pub enum Error {
     InvalidKey,
     #[error("Vault locked: too many failed unseal attempts")]
     LockedOut,
-
     #[error("State transition failed")]
     State,
-
+    #[error("Vault ceremony failed: {0}")]
+    Ceremony(#[from] vault_coordinator::Error),
     #[error("Internal error: {0}")]
     Internal(String),
 }
+
 impl Error {
     fn internal(message: impl Into<String>) -> Self {
         Self::Internal(message.into())
     }
+
+    /// Preserve the coordinator's own error so the operator learns why a
+    /// ceremony was refused instead of reading "internal error".
+    fn ceremony<M>(error: SendError<M, vault_coordinator::Error>) -> Self {
+        match error {
+            SendError::HandlerError(inner) => Self::Ceremony(inner),
+            _ => Self::internal("VaultCoordinator unavailable"),
+        }
+    }
 }
 
 pub struct HandshakeResponse {
@@ -71,7 +82,6 @@ impl VaultGate {
 
 impl Actor for VaultGate {
     type Args = Self;
-
     type Error = ();
 
     async fn on_start(
@@ -101,17 +111,11 @@ impl VaultGate {
         ciphertext: &[u8],
         associated_data: &[u8],
     ) -> Result<SafeCell<Vec<u8>>, ()> {
-        let Ok(nonce) = XNonce::try_from(nonce) else {
-            error!("Encrypted key material carries a nonce of the wrong length");
-            return Err(());
-        };
-
+        let nonce = XNonce::from_slice(nonce);
         let cipher = XChaCha20Poly1305::new(secret.as_bytes().into());
-
         let mut key_buffer = SafeCell::new(ciphertext.to_vec());
-
         let decryption_result = key_buffer.write_inline(|write_handle| {
-            cipher.decrypt_in_place(&nonce, associated_data, write_handle)
+            cipher.decrypt_in_place(nonce, associated_data, write_handle)
         });
 
         match decryption_result {
@@ -122,9 +126,13 @@ impl VaultGate {
             }
         }
     }
+
+    fn key_cell(buffer: SafeCell<Vec<u8>>) -> Result<KeyCell, Error> {
+        KeyCell::try_from(buffer).map_err(|()| Error::InvalidKey)
+    }
 }
 
-#[messages(messages = Inbound, replies = Outbound)]
+#[messages]
 impl VaultGate {
     #[message]
     pub fn handle_handshake(
@@ -133,14 +141,11 @@ impl VaultGate {
     ) -> Result<HandshakeResponse, Error> {
         let ephemeral_secret = EphemeralSecret::random();
         let public_key = PublicKey::from(&ephemeral_secret);
-
         let secret = ephemeral_secret.diffie_hellman(&client_pubkey);
-
         self.state = State::ReadyForExchange {
             server_key: public_key,
             secret,
         };
-
         Ok(HandshakeResponse {
             server_pubkey: public_key,
         })
@@ -156,20 +161,11 @@ impl VaultGate {
         let State::ReadyForExchange { secret, .. } = &self.state else {
             return Err(Error::State);
         };
+        let seal_key = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
+            .map_err(|()| Error::InvalidKey)
+            .and_then(Self::key_cell)?;
 
-        let Ok(seal_key_buffer) = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
-        else {
-            return Err(Error::InvalidKey);
-        };
-
-        match self
-            .actors
-            .vault
-            .ask(TryUnseal {
-                seal_key_raw: seal_key_buffer,
-            })
-            .await
-        {
+        match self.actors.vault.ask(TryUnseal { seal_key }).await {
             Ok(()) => {
                 info!("Successfully unsealed key with client-provided key");
                 Ok(())
@@ -197,17 +193,16 @@ impl VaultGate {
         let State::ReadyForExchange { secret, .. } = &self.state else {
             return Err(Error::State);
         };
-
-        let Ok(seal_key_buffer) = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
-        else {
-            return Err(Error::InvalidKey);
-        };
+        let seal_key = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
+            .map_err(|()| Error::InvalidKey)
+            .and_then(Self::key_cell)?;
 
         match self
             .actors
             .vault
             .ask(Bootstrap {
-                seal_key_raw: seal_key_buffer,
+                seal_key,
+                custody: None,
             })
             .await
         {
@@ -231,14 +226,53 @@ impl VaultGate {
 
     #[message]
     pub async fn handle_vault_state(&mut self) -> Result<VaultState, Error> {
-        let answer = self
-            .actors
+        self.actors
             .vault
             .ask(GetState {})
             .await
-            .map_err(|_| Error::internal("failed to query vault"))?;
+            .map_err(|_| Error::internal("failed to query vault"))
+    }
 
-        Ok(answer)
+    #[message]
+    pub async fn handle_declare_committee(&mut self, count: usize) -> Result<(), Error> {
+        self.actors
+            .vault_coordinator
+            .ask(StartBootstrap {
+                operator_id: self.auth_creds.id,
+                declared_count: count,
+            })
+            .await
+            .map_err(Error::ceremony)
+    }
+
+    #[message]
+    pub async fn handle_contribute_bootstrap_passphrase(
+        &mut self,
+        passphrase: Vec<u8>,
+    ) -> Result<bool, Error> {
+        self.actors
+            .vault_coordinator
+            .ask(ContributeBootstrap {
+                operator_id: self.auth_creds.id,
+                passphrase: SafeCell::new(passphrase),
+            })
+            .await
+            .map_err(Error::ceremony)
+    }
+
+    #[message]
+    pub async fn handle_contribute_unseal_passphrase(
+        &mut self,
+        passphrase: Vec<u8>,
+    ) -> Result<bool, Error> {
+        self.actors
+            .vault_coordinator
+            .ask(ContributeUnseal {
+                operator_id: self.auth_creds.id,
+                passphrase: SafeCell::new(passphrase),
+            })
+            .await
+            .map_err(Error::ceremony)
     }
 }
 
@@ -292,3 +326,75 @@ impl Message<events::Unsealed> for VaultGate {
         ctx.stop();
     }
 }
+
+pub enum Inbound {
+    HandleHandshake(HandleHandshake),
+    HandleUnsealEncryptedKey(HandleUnsealEncryptedKey),
+    HandleBootstrapEncryptedKey(HandleBootstrapEncryptedKey),
+    HandleVaultState,
+    HandleDeclareCommittee(HandleDeclareCommittee),
+    HandleContributeBootstrapPassphrase(HandleContributeBootstrapPassphrase),
+    HandleContributeUnsealPassphrase(HandleContributeUnsealPassphrase),
+}
+
+pub enum Outbound {
+    HandleHandshake(Result<HandshakeResponse, Error>),
+    HandleUnsealEncryptedKey(Result<(), Error>),
+    HandleBootstrapEncryptedKey(Result<(), Error>),
+    HandleVaultState(Result<VaultState, Error>),
+    HandleDeclareCommittee(Result<(), Error>),
+    HandleContributeBootstrapPassphrase(Result<bool, Error>),
+    HandleContributeUnsealPassphrase(Result<bool, Error>),
+}
+
+impl Message<Inbound> for VaultGate {
+    type Reply = Result<Outbound, Error>;
+
+    async fn handle(
+        &mut self,
+        msg: Inbound,
+        _ctx: &mut kameo::prelude::Context<Self, Self::Reply>,
+    ) -> Self::Reply {
+        match msg {
+            Inbound::HandleHandshake(message) => Ok(Outbound::HandleHandshake(
+                self.handle_handshake(message.client_pubkey),
+            )),
+            Inbound::HandleUnsealEncryptedKey(message) => Ok(Outbound::HandleUnsealEncryptedKey(
+                self.handle_unseal_encrypted_key(
+                    message.nonce,
+                    message.ciphertext,
+                    message.associated_data,
+                )
+                .await,
+            )),
+            Inbound::HandleBootstrapEncryptedKey(message) => {
+                Ok(Outbound::HandleBootstrapEncryptedKey(
+                    self.handle_bootstrap_encrypted_key(
+                        message.nonce,
+                        message.ciphertext,
+                        message.associated_data,
+                    )
+                    .await,
+                ))
+            }
+            Inbound::HandleVaultState => {
+                Ok(Outbound::HandleVaultState(self.handle_vault_state().await))
+            }
+            Inbound::HandleDeclareCommittee(message) => Ok(Outbound::HandleDeclareCommittee(
+                self.handle_declare_committee(message.count).await,
+            )),
+            Inbound::HandleContributeBootstrapPassphrase(message) => {
+                Ok(Outbound::HandleContributeBootstrapPassphrase(
+                    self.handle_contribute_bootstrap_passphrase(message.passphrase)
+                        .await,
+                ))
+            }
+            Inbound::HandleContributeUnsealPassphrase(message) => {
+                Ok(Outbound::HandleContributeUnsealPassphrase(
+                    self.handle_contribute_unseal_passphrase(message.passphrase)
+                        .await,
+                ))
+            }
+        }
+    }
+}

server/crates/arbiter-server/tests/client/auth.rs

@@ -1,22 +1,19 @@
 use super::common::ChannelTransport;
-use arbiter_crypto::{
-    authn::{self, AuthChallenge, CLIENT_CONTEXT},
-    safecell::{SafeCell, SafeCellHandle as _},
-};
+use arbiter_crypto::authn::{self, AuthChallenge, CLIENT_CONTEXT};
 use arbiter_proto::{
     ClientMetadata,
     transport::{Receiver, Sender},
 };
 use arbiter_server::{
     actors::{GlobalActors, vault::Bootstrap},
-    crypto::integrity,
+    crypto::{KeyCell, integrity},
     db::{self, schema},
     peers::client::{ClientConnection, ClientCredentials, auth, connect_client},
 };
 
 use diesel::{ExpressionMethods as _, NullableExpressionMethods as _, QueryDsl as _, insert_into};
 use diesel_async::RunQueryDsl;
-use ml_dsa::{Generate as _, MlDsa87, SigningKey, VerifyingKey, signature::Keypair};
+use ml_dsa::{KeyGen, MlDsa87, SigningKey, VerifyingKey, signature::Keypair};
 
 fn metadata(name: &str, description: Option<&str>, version: Option<&str>) -> ClientMetadata {
     ClientMetadata {
@@ -73,7 +70,7 @@ async fn insert_registered_client(
 
 fn sign_client_challenge(key: &SigningKey<MlDsa87>, challenge: &AuthChallenge) -> authn::Signature {
     let challenge = challenge.format();
-    key.expanded_key()
+    key.signing_key()
         .sign_deterministic(&challenge, CLIENT_CONTEXT)
         .unwrap()
         .into()
@@ -81,7 +78,7 @@ fn sign_client_challenge(key: &SigningKey<MlDsa87>, challenge: &AuthChallenge) -
 
 async fn insert_bootstrap_sentinel_operator(db: &db::DatabasePool) {
     let mut conn = db.get().await.unwrap();
-    let sentinel_key = verifying_key(&SigningKey::<MlDsa87>::generate())
+    let sentinel_key = verifying_key(&MlDsa87::key_gen(&mut rand::rng()))
         .encode()
         .0
         .to_vec();
@@ -100,7 +97,8 @@ async fn spawn_test_actors(db: &db::DatabasePool) -> GlobalActors {
     actors
         .vault
         .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
         })
         .await
         .unwrap();
@@ -120,7 +118,7 @@ pub async fn unregistered_pubkey_rejected() {
         connect_client(props, &mut server_transport).await;
     });
 
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
 
     test_transport
         .send(auth::Inbound::AuthChallengeRequest {
@@ -140,7 +138,7 @@ pub async fn challenge_auth() {
     let db = db::create_test_pool().await;
     let actors = spawn_test_actors(&db).await;
 
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
 
     Box::pin(insert_registered_client(
         &db,
@@ -206,7 +204,7 @@ pub async fn challenge_auth() {
 pub async fn metadata_unchanged_does_not_append_history() {
     let db = db::create_test_pool().await;
     let actors = spawn_test_actors(&db).await;
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
     let requested = metadata("client", Some("desc"), Some("1.0.0"));
 
     Box::pin(insert_registered_client(
@@ -269,7 +267,7 @@ pub async fn metadata_unchanged_does_not_append_history() {
 pub async fn metadata_frozen_after_approval_ignores_reconnect_changes() {
     let db = db::create_test_pool().await;
     let actors = spawn_test_actors(&db).await;
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
 
     Box::pin(insert_registered_client(
         &db,
@@ -340,7 +338,10 @@ pub async fn metadata_frozen_after_approval_ignores_reconnect_changes() {
             .first::<(String, Option<String>, Option<String>)>(&mut conn)
             .await
             .unwrap();
-        assert_eq!(metadata_count, 1, "frozen: no new metadata row on reconnect");
+        assert_eq!(
+            metadata_count, 1,
+            "frozen: no new metadata row on reconnect"
+        );
         assert_eq!(history_count, 0, "frozen: no history entry on reconnect");
         assert_eq!(
             current,
@@ -360,7 +361,7 @@ pub async fn challenge_auth_rejects_integrity_tag_mismatch() {
     let db = db::create_test_pool().await;
     let actors = spawn_test_actors(&db).await;
 
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
     let requested = metadata("client", Some("desc"), Some("1.0.0"));
 
     {

server/crates/arbiter-server/tests/common/mod.rs

@@ -2,10 +2,11 @@
     dead_code,
     reason = "Common test utilities that may not be used in every test"
 )]
-use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+
 use arbiter_proto::transport::{Bi, Error, Receiver, Sender};
 use arbiter_server::{
     actors::{GlobalActors, vault::Vault},
+    crypto::KeyCell,
     db::{self, schema},
 };
 
@@ -19,7 +20,7 @@ pub(crate) async fn bootstrapped_vault(db: &db::DatabasePool) -> Vault {
         .await
         .unwrap();
     actor
-        .bootstrap(SafeCell::new(b"test-seal-key".to_vec()))
+        .bootstrap(KeyCell::from([0u8; 32]), None)
         .await
         .unwrap();
     actor

server/crates/arbiter-server/tests/operator/auth.rs

@@ -1,20 +1,17 @@
 use super::common::ChannelTransport;
-use arbiter_crypto::{
-    authn::{self, AuthChallenge, OPERATOR_CONTEXT},
-    safecell::{SafeCell, SafeCellHandle as _},
-};
+use arbiter_crypto::authn::{self, AuthChallenge, OPERATOR_CONTEXT};
 use arbiter_proto::transport::{Error as TransportError, Receiver, Sender};
 use arbiter_server::{
     actors::{GlobalActors, bootstrap::GetToken, vault::Bootstrap},
-    crypto::integrity,
-    db::{self, schema},
+    crypto::{KeyCell, integrity},
+    db::{self, models::OperatorId, schema},
     peers::operator::{self, Credentials, OperatorConnection, auth, vault_gate},
 };
 
 use async_trait::async_trait;
 use diesel::{ExpressionMethods as _, QueryDsl, insert_into};
 use diesel_async::RunQueryDsl;
-use ml_dsa::{Generate as _, MlDsa87, SigningKey, VerifyingKey, signature::Keypair};
+use ml_dsa::{KeyGen, MlDsa87, SigningKey, VerifyingKey, signature::Keypair};
 use tokio::sync::mpsc;
 
 fn verifying_key(key: &SigningKey<MlDsa87>) -> VerifyingKey<MlDsa87> {
@@ -26,7 +23,7 @@ fn sign_operator_challenge(
     challenge: &AuthChallenge,
 ) -> authn::Signature {
     let challenge = challenge.format();
-    key.expanded_key()
+    key.signing_key()
         .sign_deterministic(&challenge, OPERATOR_CONTEXT)
         .unwrap()
         .into()
@@ -154,13 +151,6 @@ impl Sender<auth::Inbound> for StartTestTransport {
 pub async fn bootstrap_token_auth() {
     let db = db::create_test_pool().await;
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
-    actors
-        .vault
-        .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
-        })
-        .await
-        .unwrap();
     let token = actors.bootstrapper.ask(GetToken).await.unwrap().unwrap();
 
     let (mut server_transport, mut test_transport) = ChannelTransport::new();
@@ -170,7 +160,7 @@ pub async fn bootstrap_token_auth() {
         auth::authenticate(&mut props, &mut server_transport).await
     });
 
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
     test_transport
         .send(auth::Inbound::AuthChallengeRequest {
             pubkey: verifying_key(&new_key).into(),
@@ -227,7 +217,7 @@ pub async fn bootstrap_invalid_token_auth() {
         auth::authenticate(&mut props, &mut server_transport).await
     });
 
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
     test_transport
         .send(auth::Inbound::AuthChallengeRequest {
             pubkey: verifying_key(&new_key).into(),
@@ -275,20 +265,21 @@ pub async fn challenge_auth() {
     actors
         .vault
         .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
         })
         .await
         .unwrap();
 
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
     let pubkey_bytes = authn::PublicKey::from(verifying_key(&new_key)).to_bytes();
 
     {
         let mut conn = db.get().await.unwrap();
-        let id: i32 = insert_into(schema::operator_identity::table)
+        let id: OperatorId = insert_into(schema::operator_identity::table)
             .values((schema::operator_identity::public_key.eq(pubkey_bytes.clone()),))
             .returning(schema::operator_identity::id)
-            .get_result(&mut conn)
+            .get_result::<OperatorId>(&mut conn)
             .await
             .unwrap();
         integrity::sign_entity(
@@ -361,12 +352,13 @@ pub async fn challenge_auth_rejects_integrity_tag_mismatch_when_unsealed() {
     actors
         .vault
         .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
         })
         .await
         .unwrap();
 
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
     let pubkey_bytes = authn::PublicKey::from(verifying_key(&new_key)).to_bytes();
 
     {
@@ -434,20 +426,21 @@ pub async fn challenge_auth_rejects_invalid_signature() {
     actors
         .vault
         .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
         })
         .await
         .unwrap();
 
-    let new_key = SigningKey::<MlDsa87>::generate();
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
     let pubkey_bytes = authn::PublicKey::from(verifying_key(&new_key)).to_bytes();
 
     {
         let mut conn = db.get().await.unwrap();
-        let id: i32 = insert_into(schema::operator_identity::table)
+        let id: OperatorId = insert_into(schema::operator_identity::table)
             .values((schema::operator_identity::public_key.eq(pubkey_bytes.clone()),))
             .returning(schema::operator_identity::id)
-            .get_result(&mut conn)
+            .get_result::<OperatorId>(&mut conn)
             .await
             .unwrap();
         integrity::sign_entity(
@@ -506,3 +499,92 @@ pub async fn challenge_auth_rejects_invalid_signature() {
         Err(auth::Error::InvalidChallengeSolution)
     ));
 }
+
+/// The bootstrap token authorises registering committee members *before* the
+/// vault exists. Once any bootstrap path succeeds it must stop working, or its
+/// holder could keep minting operator identities until the next restart.
+#[tokio::test]
+#[test_log::test]
+pub async fn bootstrap_token_rejected_after_bootstrap() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let token = actors.bootstrapper.ask(GetToken).await.unwrap().unwrap();
+
+    actors
+        .vault
+        .ask(Bootstrap {
+            seal_key: KeyCell::from([0u8; 32]),
+            custody: None,
+        })
+        .await
+        .unwrap();
+
+    // `Bootstrapped` travels through the message bus, so the token disappears
+    // a couple of actor turns after the bootstrap call returns.
+    let mut retired = false;
+    for _ in 0..100 {
+        if actors.bootstrapper.ask(GetToken).await.unwrap().is_none() {
+            retired = true;
+            break;
+        }
+        tokio::task::yield_now().await;
+    }
+    assert!(
+        retired,
+        "the bootstrap token must be retired once the vault is bootstrapped"
+    );
+
+    let (mut server_transport, mut test_transport) = ChannelTransport::new();
+    let db_for_task = db.clone();
+    let task = tokio::spawn(async move {
+        let mut props = OperatorConnection::new(db_for_task, actors);
+        auth::authenticate(&mut props, &mut server_transport).await
+    });
+
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
+    test_transport
+        .send(auth::Inbound::AuthChallengeRequest {
+            pubkey: verifying_key(&new_key).into(),
+            bootstrap_token: Some(token.into_bytes()),
+        })
+        .await
+        .unwrap();
+
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(auth::Outbound::AuthChallenge { challenge }) => challenge,
+        other => panic!("Expected AuthChallenge, got {other:?}"),
+    };
+
+    let signature = sign_operator_challenge(&new_key, &challenge);
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution {
+            signature: signature.to_bytes(),
+        })
+        .await
+        .unwrap();
+
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive auth result");
+    assert!(
+        matches!(response, Err(auth::Error::InvalidBootstrapToken)),
+        "a spent bootstrap token must not authorise a new identity, got {response:?}"
+    );
+    assert!(task.await.unwrap().is_err(), "authentication must fail");
+
+    let mut conn = db.get().await.unwrap();
+    let registered: i64 = schema::operator_identity::table
+        .count()
+        .get_result(&mut conn)
+        .await
+        .unwrap();
+    assert_eq!(
+        registered, 0,
+        "no identity may be registered after the bootstrap"
+    );
+}

server/crates/arbiter-server/tests/operator/unseal.rs

@@ -1,13 +1,11 @@
-use arbiter_crypto::{
-    authn,
-    safecell::{SafeCell, SafeCellHandle as _},
-};
+use arbiter_crypto::authn;
 use arbiter_server::{
     actors::{
         GlobalActors,
         vault::{Bootstrap, Seal},
     },
-    db,
+    crypto::KeyCell,
+    db::{self, models::OperatorId},
     peers::operator::{
         Credentials,
         vault_gate::{
@@ -16,13 +14,13 @@ use arbiter_server::{
     },
 };
 
-use chacha20poly1305::{AeadInOut, XChaCha20Poly1305, XNonce, aead::KeyInit};
+use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
 use kameo::actor::Spawn as _;
 use tokio::sync::oneshot;
 use x25519_dalek::{EphemeralSecret, PublicKey};
 
 async fn setup_sealed_gate(
-    seal_key: &[u8],
+    seal_key: [u8; 32],
 ) -> (
     db::DatabasePool,
     kameo::actor::ActorRef<VaultGate>,
@@ -34,7 +32,8 @@ async fn setup_sealed_gate(
     actors
         .vault
         .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(seal_key.to_vec()),
+            seal_key: KeyCell::from(seal_key),
+            custody: None,
         })
         .await
         .unwrap();
@@ -42,7 +41,10 @@ async fn setup_sealed_gate(
 
     let (promotion_tx, promotion_rx) = oneshot::channel();
     let pubkey = authn::SigningKey::generate().public_key();
-    let auth_creds = Credentials { id: 1, pubkey };
+    let auth_creds = Credentials {
+        id: OperatorId::from_raw(1),
+        pubkey,
+    };
     let gate = VaultGate::spawn(VaultGate::new(auth_creds, actors, db.clone(), promotion_tx));
 
     (db, gate, promotion_rx)
@@ -83,10 +85,10 @@ async fn client_dh_encrypt(
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_success() {
-    let seal_key = b"test-seal-key";
+    let seal_key = [7u8; 32];
     let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;
 
-    let encrypted_key = client_dh_encrypt(&gate, seal_key).await;
+    let encrypted_key = client_dh_encrypt(&gate, &seal_key).await;
 
     let response = gate.ask(encrypted_key).await;
     assert!(matches!(response, Ok(())));
@@ -95,10 +97,10 @@ pub async fn unseal_success() {
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_wrong_seal_key() {
-    let seal_key = b"test-seal-key";
+    let seal_key = [7u8; 32];
     let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;
 
-    let encrypted_key = client_dh_encrypt(&gate, b"wrong-key").await;
+    let encrypted_key = client_dh_encrypt(&gate, &[8u8; 32]).await;
 
     let response = gate.ask(encrypted_key).await;
     assert!(matches!(
@@ -112,7 +114,7 @@ pub async fn unseal_wrong_seal_key() {
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_corrupted_ciphertext() {
-    let seal_key = b"test-seal-key";
+    let seal_key = [7u8; 32];
     let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;
 
     let client_secret = EphemeralSecret::random();
@@ -143,11 +145,11 @@ pub async fn unseal_corrupted_ciphertext() {
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_retry_after_invalid_key() {
-    let seal_key = b"real-seal-key";
+    let seal_key = [9u8; 32];
     let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;
 
     {
-        let encrypted_key = client_dh_encrypt(&gate, b"wrong-key").await;
+        let encrypted_key = client_dh_encrypt(&gate, &[8u8; 32]).await;
 
         let response = gate.ask(encrypted_key).await;
         assert!(matches!(
@@ -159,7 +161,7 @@ pub async fn unseal_retry_after_invalid_key() {
     }
 
     {
-        let encrypted_key = client_dh_encrypt(&gate, seal_key).await;
+        let encrypted_key = client_dh_encrypt(&gate, &seal_key).await;
 
         let response = gate.ask(encrypted_key).await;
         assert!(matches!(response, Ok(())));

server/crates/arbiter-server/tests/vault.rs

@@ -2,6 +2,8 @@ mod common;
 
 #[path = "vault/concurrency.rs"]
 mod concurrency;
+#[path = "vault/custody.rs"]
+mod custody;
 #[path = "vault/lifecycle.rs"]
 mod lifecycle;
 #[path = "vault/storage.rs"]

server/crates/arbiter-server/tests/vault/concurrency.rs

@@ -5,6 +5,7 @@ use arbiter_server::{
         GlobalActors,
         vault::{CreateNew, Error, Vault},
     },
+    crypto::KeyCell,
     db::{self, models, schema},
 };
 
@@ -169,7 +170,7 @@ async fn decrypt_roundtrip_after_high_concurrency() {
         .await
         .unwrap();
     decryptor
-        .try_unseal(SafeCell::new(b"test-seal-key".to_vec()))
+        .try_unseal(KeyCell::from([0u8; 32]))
         .await
         .unwrap();
 

server/crates/arbiter-server/tests/vault/custody.rs

@@ -0,0 +1,317 @@
+//! End-to-end coverage for the Shamir custody ceremonies.
+
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use arbiter_server::{
+    actors::{
+        GlobalActors,
+        vault::{Bootstrap, GetState, Seal, VaultState},
+        vault_coordinator::{ContributeBootstrap, ContributeUnseal, StartBootstrap},
+    },
+    crypto::{KeyCell, shamir},
+    db::{self, models::OperatorId, schema},
+};
+
+use diesel::{ExpressionMethods as _, QueryDsl};
+use diesel_async::RunQueryDsl;
+
+/// Register `count` operator identities so committee members satisfy the
+/// foreign key from `operator` to `operator_identity`.
+async fn register_operators(db: &db::DatabasePool, count: usize) -> Vec<OperatorId> {
+    let mut conn = db.get().await.unwrap();
+    let mut ids = Vec::with_capacity(count);
+    for index in 0..count {
+        let pubkey = vec![u8::try_from(index).unwrap(); 32];
+        let id: OperatorId = diesel::insert_into(schema::operator_identity::table)
+            .values((schema::operator_identity::public_key.eq(pubkey),))
+            .returning(schema::operator_identity::id)
+            .get_result(&mut conn)
+            .await
+            .unwrap();
+        ids.push(id);
+    }
+    ids
+}
+
+async fn stored_share_count(db: &db::DatabasePool) -> i64 {
+    let mut conn = db.get().await.unwrap();
+    schema::operator::table
+        .count()
+        .get_result(&mut conn)
+        .await
+        .unwrap()
+}
+
+async fn stored_threshold(db: &db::DatabasePool) -> Option<i32> {
+    let mut conn = db.get().await.unwrap();
+    schema::arbiter_settings::table
+        .select(schema::arbiter_settings::shamir_threshold)
+        .first(&mut conn)
+        .await
+        .unwrap()
+}
+
+fn passphrase(seed: u8) -> SafeCell<Vec<u8>> {
+    SafeCell::new(vec![seed; 16])
+}
+
+/// The happy path: three operators bootstrap, and any two of them reopen the
+/// vault after it is sealed.
+#[tokio::test]
+#[test_log::test]
+async fn committee_of_three_unseals_with_two_passphrases() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 3).await;
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 3,
+        })
+        .await
+        .unwrap();
+
+    for (index, operator_id) in operators.iter().enumerate() {
+        let finished = actors
+            .vault_coordinator
+            .ask(ContributeBootstrap {
+                operator_id: *operator_id,
+                passphrase: passphrase(u8::try_from(index).unwrap()),
+            })
+            .await
+            .unwrap();
+        assert_eq!(
+            finished,
+            index == 2,
+            "the ceremony finishes only on the last contribution"
+        );
+    }
+
+    assert_eq!(
+        actors.vault.ask(GetState {}).await.unwrap(),
+        VaultState::Unsealed
+    );
+    assert_eq!(stored_share_count(&db).await, 3);
+    assert_eq!(stored_threshold(&db).await, Some(2));
+
+    actors.vault.ask(Seal {}).await.unwrap();
+
+    let first = actors
+        .vault_coordinator
+        .ask(ContributeUnseal {
+            operator_id: operators[0],
+            passphrase: passphrase(0),
+        })
+        .await
+        .unwrap();
+    assert!(!first, "one of two shares must not unseal");
+
+    let second = actors
+        .vault_coordinator
+        .ask(ContributeUnseal {
+            operator_id: operators[2],
+            passphrase: passphrase(2),
+        })
+        .await
+        .unwrap();
+    assert!(second, "the threshold contribution should unseal the vault");
+    assert_eq!(
+        actors.vault.ask(GetState {}).await.unwrap(),
+        VaultState::Unsealed
+    );
+}
+
+/// Shares that describe a seal key the vault never adopted would make the vault
+/// permanently un-unsealable, so a refused bootstrap must leave the table empty.
+#[tokio::test]
+#[test_log::test]
+async fn refused_bootstrap_stores_no_shares() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 1).await;
+
+    // Another path bootstraps the vault first; the ceremony now has nowhere to go.
+    actors
+        .vault
+        .ask(Bootstrap {
+            seal_key: KeyCell::from([4u8; 32]),
+            custody: None,
+        })
+        .await
+        .unwrap();
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 1,
+        })
+        .await
+        .unwrap();
+
+    let error = actors
+        .vault_coordinator
+        .ask(ContributeBootstrap {
+            operator_id: operators[0],
+            passphrase: passphrase(1),
+        })
+        .await
+        .expect_err("bootstrapping an already bootstrapped vault must fail");
+    assert!(
+        format!("{error:?}").contains("AlreadyBootstrapped"),
+        "expected AlreadyBootstrapped, got {error:?}"
+    );
+
+    assert_eq!(
+        stored_share_count(&db).await,
+        0,
+        "a refused bootstrap must not leave shares behind"
+    );
+    assert_eq!(
+        stored_threshold(&db).await,
+        None,
+        "a refused bootstrap must not leave a threshold behind"
+    );
+}
+
+#[tokio::test]
+#[test_log::test]
+async fn oversized_and_degenerate_committees_are_rejected() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 1).await;
+
+    for (count, expected) in [
+        (0_usize, "EmptyCommittee"),
+        (2, "UnsupportedCommittee"),
+        (shamir::MAX_COMMITTEE_SIZE + 1, "CommitteeTooLarge"),
+        (usize::MAX, "CommitteeTooLarge"),
+    ] {
+        let error = actors
+            .vault_coordinator
+            .ask(StartBootstrap {
+                operator_id: operators[0],
+                declared_count: count,
+            })
+            .await
+            .expect_err("committee size must be rejected");
+        assert!(
+            format!("{error:?}").contains(expected),
+            "expected {expected} for count {count}, got {error:?}"
+        );
+    }
+}
+
+/// A committee whose members never all show up would otherwise wedge the
+/// coordinator until restart. Only the operator that declared it may reset it.
+#[tokio::test]
+#[test_log::test]
+async fn only_the_declarer_may_restart_a_stalled_committee() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 3).await;
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 3,
+        })
+        .await
+        .unwrap();
+    actors
+        .vault_coordinator
+        .ask(ContributeBootstrap {
+            operator_id: operators[0],
+            passphrase: passphrase(0),
+        })
+        .await
+        .unwrap();
+
+    let error = actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[1],
+            declared_count: 3,
+        })
+        .await
+        .expect_err("a bystander must not reset someone else's ceremony");
+    assert!(
+        format!("{error:?}").contains("AlreadyBootstrapping"),
+        "expected AlreadyBootstrapping, got {error:?}"
+    );
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 1,
+        })
+        .await
+        .expect("the declarer may restart the ceremony");
+
+    let finished = actors
+        .vault_coordinator
+        .ask(ContributeBootstrap {
+            operator_id: operators[0],
+            passphrase: passphrase(0),
+        })
+        .await
+        .unwrap();
+    assert!(
+        finished,
+        "the restarted one-operator ceremony should complete"
+    );
+    assert_eq!(stored_share_count(&db).await, 1);
+}
+
+/// A wrong passphrase must not unseal, and the operator must be able to retry.
+#[tokio::test]
+#[test_log::test]
+async fn wrong_passphrase_is_rejected_and_retryable() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let operators = register_operators(&db, 1).await;
+
+    actors
+        .vault_coordinator
+        .ask(StartBootstrap {
+            operator_id: operators[0],
+            declared_count: 1,
+        })
+        .await
+        .unwrap();
+    actors
+        .vault_coordinator
+        .ask(ContributeBootstrap {
+            operator_id: operators[0],
+            passphrase: passphrase(7),
+        })
+        .await
+        .unwrap();
+    actors.vault.ask(Seal {}).await.unwrap();
+
+    let error = actors
+        .vault_coordinator
+        .ask(ContributeUnseal {
+            operator_id: operators[0],
+            passphrase: passphrase(8),
+        })
+        .await
+        .expect_err("a wrong passphrase must not unseal");
+    assert!(
+        format!("{error:?}").contains("InvalidPassphrase"),
+        "expected InvalidPassphrase, got {error:?}"
+    );
+
+    let unsealed = actors
+        .vault_coordinator
+        .ask(ContributeUnseal {
+            operator_id: operators[0],
+            passphrase: passphrase(7),
+        })
+        .await
+        .expect("the operator may retry with the correct passphrase");
+    assert!(unsealed, "the retry should unseal the vault");
+}

server/crates/arbiter-server/tests/vault/lifecycle.rs

@@ -5,7 +5,10 @@ use arbiter_server::{
         GlobalActors,
         vault::{Error, Vault},
     },
-    crypto::encryption::v1::{Nonce, ROOT_KEY_TAG},
+    crypto::{
+        KeyCell,
+        encryption::v1::{Nonce, ROOT_KEY_TAG},
+    },
     db::{self, models, schema},
 };
 
@@ -22,8 +25,8 @@ async fn bootstrap() {
         .await
         .unwrap();
 
-    let seal_key = SafeCell::new(b"test-seal-key".to_vec());
-    actor.bootstrap(seal_key).await.unwrap();
+    let seal_key = KeyCell::from([0u8; 32]);
+    actor.bootstrap(seal_key, None).await.unwrap();
 
     let mut conn = db.get().await.unwrap();
     let row: models::RootKeyHistory = schema::root_key_history::table
@@ -45,8 +48,8 @@ async fn bootstrap_rejects_double() {
     let db = db::create_test_pool().await;
     let mut actor = common::bootstrapped_vault(&db).await;
 
-    let seal_key2 = SafeCell::new(b"test-seal-key".to_vec());
-    let err = actor.bootstrap(seal_key2).await.unwrap_err();
+    let seal_key2 = KeyCell::from([0u8; 32]);
+    let err = actor.bootstrap(seal_key2, None).await.unwrap_err();
     assert!(matches!(err, Error::AlreadyBootstrapped));
 }
 
@@ -107,7 +110,7 @@ async fn unseal_correct_password() {
     let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
         .await
         .unwrap();
-    let seal_key = SafeCell::new(b"test-seal-key".to_vec());
+    let seal_key = KeyCell::from([0u8; 32]);
     actor.try_unseal(seal_key).await.unwrap();
 
     let mut decrypted = actor.decrypt(aead_id, TEST_AAD.to_vec()).await.unwrap();
@@ -131,11 +134,11 @@ async fn unseal_wrong_then_correct_password() {
         .await
         .unwrap();
 
-    let bad_key = SafeCell::new(b"wrong-password".to_vec());
+    let bad_key = KeyCell::from([1u8; 32]);
     let err = actor.try_unseal(bad_key).await.unwrap_err();
     assert!(matches!(err, Error::InvalidKey));
 
-    let good_key = SafeCell::new(b"test-seal-key".to_vec());
+    let good_key = KeyCell::from([0u8; 32]);
     actor.try_unseal(good_key).await.unwrap();
 
     let mut decrypted = actor.decrypt(aead_id, TEST_AAD.to_vec()).await.unwrap();