refactor: upgrade aes gcm 0.11.0

[metalurgical]

This PR upgrades the aes-gcm crate from version 0.10.3 to 0.11.0.

[metalurgical]

Resolves #3770
Closes #3770

[gilcu3]

@claude review

[claude]

Pull request overview

Upgrades aes-gcm from 0.10.3 to 0.11.0 and migrates the four call sites in mpc-node (DB encryption, migration-service web encryption, and two test helpers) to the new RustCrypto trait layout (aead 0.6 / cipher 0.5 / hybrid-array). Nonce and key generation move from AeadCore::generate_nonce / Aes*Gcm::generate_key to the new Generate trait, and nonces are now built via Nonce::<Aes*Gcm>::try_from(...) instead of .into().

Changes:

• Bump workspace aes-gcm pin to 0.11.0 (Cargo.toml, Cargo.lock).
• Migrate crates/node/src/db.rs encrypt/decrypt to Generate + explicit Nonce::<Aes128Gcm>::try_from.
• Migrate crates/node/src/migration_service/web/encryption.rs to the same pattern for Aes256Gcm.
• Update test-only helpers in crates/node/src/migration_service/web/test_utils.rs and crates/node/src/tests.rs to use Key::<Aes256Gcm>::generate().

Reviewed changes

Per-file summary

File	Description
Cargo.toml / Cargo.lock	Bump aes-gcm to 0.11 and pull in new transitive versions (aead 0.6, cipher 0.5, ghash 0.6, polyval 0.7, universal-hash 0.6, inout 0.2, cpubits).
crates/node/src/db.rs	New imports (aead::{Generate, Nonce}, drop AeadCore). encrypt now uses Nonce::<Aes128Gcm>::generate(). decrypt builds the nonce via Nonce::<Aes128Gcm>::try_from(&ciphertext[..NONCE_LEN]).
crates/node/src/migration_service/web/encryption.rs	Same pattern for Aes256Gcm; removes direct OsRng import (now supplied by Generate::generate()).
crates/node/src/migration_service/web/test_utils.rs	Backup key generated via Key::<Aes256Gcm>::generate() instead of Aes256Gcm::generate_key(OsRng).
crates/node/src/tests.rs	Same key-generation swap for the integration test setup.

Findings

Blocking: none — the wire format (12-byte nonce ‖ ciphertext ‖ 16-byte tag) is unchanged, so existing on-disk DB values remain decryptable across the upgrade, and the surviving round-trip tests (db.rs:test_encrypt_decrypt, migration_service/web/encryption.rs:test_encrypt_decrypt_roundtrip and siblings) still exercise both call sites.

Non-blocking:

• crates/node/src/db.rs:76-80 — NONCE_LEN is defined locally inside decrypt but is now conceptually asserted by Nonce::<Aes128Gcm>::try_from. Consider lifting it to a const at module scope (matching migration_service/web/encryption.rs:8) or dropping the manual length check and mapping the try_from error to "ciphertext is too short" — the current code performs two overlapping length validations.
• crates/node/src/db.rs:70-72 — cipher.encrypt(&nonce, plaintext).unwrap() is preserved from the old code, but it's worth calling out as pre-existing: the only documented failure mode for AES-GCM encrypt is plaintext exceeding 2^36 − 32 bytes, which we do not enforce anywhere. Not introduced by this PR; flagging for awareness.
• crates/node/src/migration_service/web/encryption.rs:32 — pre-existing typo ("encryption failed" in the decryption error path). Not this PR's problem, but touching the file makes it a cheap drive-by fix.
• Behavioral note (no action required): the previous db::encrypt seeded nonces from rand::thread_rng() (userspace CSPRNG re-seeded from OsRng); the new Generate::generate() calls OsRng directly for every nonce, i.e. a getrandom syscall per DB write. Both are cryptographically secure; the switch is imperceptible for MPC signing throughput but worth being aware of.
• Consider adding a fixed-vector decryption test (hard-coded key + ciphertext produced by the 0.10 build) to lock in cross-version compatibility for the on-disk SecretDB format — the current tests only round-trip within a single build.

✅ Approved

[Copilot]

Pull request overview

Upgrades the workspace aes-gcm dependency to v0.11.0 and refactors nonce/key generation call sites in mpc-node to use the updated aead APIs.

Changes:

• Bump aes-gcm from 0.10.3 to 0.11.0 at the workspace level (and update Cargo.lock accordingly).
• Update AES-GCM key generation in node tests and migration-service web test utilities to use Key::<Aes256Gcm>::generate().
• Update nonce generation / parsing in migration-service encryption and SecretDB encryption helpers to use Nonce::<...>::generate() and Nonce::<...>::try_from(...).

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/node/src/tests.rs	Updates integration test secrets to generate AES-GCM backup keys using the new Key::<Aes256Gcm>::generate() API.
crates/node/src/migration_service/web/test_utils.rs	Updates migration web test setup to generate backup encryption keys with the new API.
crates/node/src/migration_service/web/encryption.rs	Refactors nonce generation/parsing and decrypt call signature to match aes-gcm 0.11 aead APIs.
crates/node/src/db.rs	Refactors SecretDB nonce generation/parsing and decrypt call signature to match aes-gcm 0.11 aead APIs.
Cargo.toml	Bumps the workspace aes-gcm version to 0.11.0.
Cargo.lock	Locks updated transitive dependency graph for the aes-gcm 0.11 upgrade.

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[gilcu3]

Thank you for your contribution @metalurgical !

[netrome]

Thanks for contributing!