feat(vault): Dart client-side crypto core (ADR-052 D-4, mobile first)#300
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…vault First slice of the client side of ADR-052 D-4 (Dart/mobile first). Pure on-device crypto over package:cryptography — only opaque ciphertext ever leaves the device. VaultCrypto: - generateVaultKey / sealBundle / openBundle — one AES-256-GCM vault key seals the whole bundle (connections + keys + passphrases + passwords, D-3). - device keypair (X25519) + wrapForDevice / unwrapForDevice — sealed-box (ephemeral X25519 -> ECDH -> HKDF-SHA256 -> AES-GCM) so the hub relays a per-device wrapped key it can't read; deviceKeyPairFromSeed reconstructs from the persisted seed. - generateRecoveryCode (160-bit base32) + wrapForRecovery / unwrapRecovery — the vault key wrapped under a director-escrowed recovery code (Argon2id), formatting- insensitive. Argon2 cost is injectable so tests stay fast. Wire formats are base64 of packed bytes matching the hub's opaque columns. Tests cover bundle round-trip + wrong-key auth failure + fresh-nonce, device wrap/unwrap + intruder rejection + seed-reconstruction, recovery round-trip + wrong-code + format tolerance, and code shape. Flutter SDK isn't available locally (per project setup), so CI analyze+test is the validation gate. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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First slice of the client side of the zero-knowledge key vault (ADR-052 D-4), Dart/mobile first. All crypto happens on-device; only opaque ciphertext leaves it (the hub sync store from #299 is a blind blob store).
VaultCrypto(lib/services/vault/vault_crypto.dart)deviceKeyPairFromSeedreconstructs a device keypair from its persisted seed.generateRecoveryCode(160-bit, dash-grouped base32) +wrapForRecovery/unwrapRecovery(vault key wrapped under a director-escrowed code via Argon2id, formatting-insensitive). Argon2 cost is injectable so tests stay fast.Wire formats are base64 of packed bytes matching the hub's opaque TEXT columns:
sealed bundle = nonce‖ct‖mac,device envelope = ephPub(32)‖box,recovery envelope = salt(16)‖box.Tests
Bundle round-trip + wrong-key auth failure + fresh-nonce; device wrap/unwrap + intruder rejection + seed-reconstruction round-trip; recovery round-trip + wrong-code failure + format tolerance; recovery-code shape.
Note on verification
The Flutter/Dart SDK isn't available in this environment (per project setup), so I could not run
flutter analyze/testlocally — CI is the validation gate. The API is written againstpackage:cryptography2.9.0, matching the existing usage inlib/services/keychain/ssh_key_service.dart. If CI flags an API signature (e.g. an Argon2id param name), it's a quick fix.Follow-ups (not in this PR)
VaultApihub sync sub-client (push/pull/devices/recovery over the feat(hub): zero-knowledge SSH key-vault sync (ADR-052 D-4) + accept ADR-052 #299 endpoints).DataPortServiceconnections+keys shape; retire the cleartext backup.Depends on #299 (hub vault store) being merged for end-to-end, but this crypto core is independent and mergeable on its own.
🤖 Generated with Claude Code