## Context
Today every JWT issued by Twenty (access, refresh, login, file, etc.) is
HMAC-signed with a per-token-type secret derived from the global
`APP_SECRET`. Rotating that secret invalidates **every** active token at
once and there is no way to scope a leak to a subset of tokens.
This PR is the first slice of a broader effort to **decouple stateful
encryption (`APP_SECRET`-derived secrets) from stateless encryption
(JWTs)**. It introduces an asymmetric (private/public key) signing path
for `ACCESS` and `REFRESH` tokens and a signing-key registry to enable
**safe rotation**: leaked keys can be revoked by flipping
`revokedAt`/`isCurrent` on the matching row without invalidating tokens
issued by other keys.
> Out of scope (intentionally): swapping stateful encryption for
`APP_SECRET`, asymmetric signing for token types other than
`ACCESS`/`REFRESH`, an admin-panel rotation UI, and an enterprise
re-encryption command. Those will land in follow-up PRs.
## What changes
- **New `core.signingKey` table** (instance command `2.5.0` /
`1778550000000`) storing both the public key (PEM, in clear) and the
private key (PEM, encrypted with `APP_SECRET` via
`SecretEncryptionService`). One row is marked `isCurrent = true`
(enforced by a partial unique index). The row's UUID `id` is used
directly as the JWT `kid`.
- When a key is rotated out, its `privateKey` is nulled (we never keep
historical private keys) but the `publicKey` row stays so previously
issued tokens can still be verified.
- **`JwtKeyManagerService`** lazily loads-or-generates the current
signing key on first use:
- If a row with `isCurrent = true` exists → decrypts and uses it.
- Otherwise → generates a fresh EC P-256 keypair, encrypts the private
key, inserts the row (UUID id = kid). Handles concurrent insert races
via the unique constraint.
- **`JwtWrapperService.signAsync()`** signs `ACCESS`/`REFRESH` payloads
with `ES256` and a `kid` header. Falls back to `HS256` if no signing key
is available (boot-time DB error, transient failure).
- **Dual-path verification** in both `JwtWrapperService.verifyJwtToken`
and the Passport `JwtAuthStrategy.secretOrKeyProvider`:
- JWT with a `kid` header → resolve the public key PEM by id and verify
with `ES256`,
- otherwise → fall back to the existing `APP_SECRET`-derived `HS256`
path (unchanged).
- **`AccessTokenService` / `RefreshTokenService`** now sign through
`signAsync` (single public surface; the routing detail stays internal to
the wrapper).
- **Public key cache**: a new `SigningKeyEntityCacheProviderService`
plugs into `CoreEntityCacheService` (`signingKeyPublicKey` namespace)
and serves PEMs by id, with the standard local-memo + Redis layering.
- **PEM strings end-to-end**: `jsonwebtoken` accepts PEM strings
directly for both sign and verify, so the manager never converts to a
Node `KeyObject` and the cache hands the PEM straight to `jwt.verify`.
## Why ES256 (and not EdDSA / RS256)
- `@nestjs/jwt` is backed by `jsonwebtoken`, which does **not** support
EdDSA today.
- ES256 keys are tiny (~120 bytes vs 1.6 kB for RS256), signatures are
short (~64 bytes), and signing/verification is fast — important since
JWT verification runs on every authenticated request.
- ES256 is widely supported and standardized (RFC 7518), with mature
ecosystem support.
## Why store the private key in DB (not env)
- No new secret to provision: existing instances already have
`APP_SECRET`, which we reuse to encrypt the private key at rest.
- Self-healing: a fresh instance auto-generates its first signing key on
first boot. Nothing to copy/paste.
- Rotation is a SQL operation against `core.signingKey`, not a redeploy
+ env mutation.
## Backward compatibility
- All previously-issued tokens (no `kid`) keep verifying through the
legacy HS256 path with their existing `APP_SECRET`-derived secret. No
forced re-login.
- Token types not in scope (`WORKSPACE_AGNOSTIC`, `API_KEY`, `FILE`,
`LOGIN`, `EMAIL_VERIFICATION`, etc.) keep their current HS256 behavior
unchanged — they still go through the synchronous
`JwtWrapperService.sign(payload, options)` with a caller-supplied
secret.
- `signWithAppSecret` is kept intentionally as the HS256 fallback path;
it will be deprecated in a follow-up PR.
- If the DB lookup/generation fails for any reason, the wrapper logs the
error and falls back to HS256 — no startup crash, no silent regression.
## Rotation story
1. Bootstrap: first signing call lazily inserts a row in
`core.signingKey` with `isCurrent = true`, `privateKey =
encrypt(pem_A)`. New tokens carry `kid_A`.
2. Rotate: `UPDATE core."signingKey" SET "isCurrent" = false,
"privateKey" = NULL WHERE id = '<kid_A>';` then insert a new row with
`isCurrent = true`. New tokens carry `kid_B`. Tokens still in flight
with `kid_A` keep verifying because the public-key row for `kid_A` is
still there.
3. Revoke: `UPDATE core."signingKey" SET "revokedAt" = now() WHERE id =
'<kid_A>';`. All tokens with `kid_A` now fail verification cleanly with
`UNAUTHENTICATED` (no 500).
4. Tokens with no `kid` (legacy) are unaffected throughout.
## Test plan
- [x] Unit: `JwtWrapperService` dual-path verification (HS256 no-kid vs
ES256 with-kid), unknown-kid → `UNAUTHENTICATED`, `signAsync` happy path
+ `null` when no key, `signAsync` rejection for non-rotatable types.
- [x] Unit: `JwtAuthStrategy` `secretOrKeyProvider` dual-path resolution
and algorithm validation.
- [x] All existing JWT/auth/application unit tests adjusted to the
renamed public method.
- [x] Integration (`jwt-key-rotation.integration-spec.ts`):
- **Happy path**: signed-up user's `ACCESS` token has `alg=ES256` +
correct UUID `kid`, the `isCurrent=true` row exists in
`core.signingKey`, `getCurrentUser` resolves.
- **Legacy fallback**: hand-crafted no-kid HS256 token verifies via the
legacy `APP_SECRET`-derived path.
- **Previous-key rotation**: token signed by a hardcoded *previous* key
whose row is pre-inserted with `privateKey = NULL` (rotated-out) still
verifies — proves the leaked-key revocation flow works in both
directions.
- **Unknown kid**: token signed with an orphan UUID `kid` is cleanly
rejected (no 500).
- [x] `npx nx typecheck twenty-server`
- [x] `npx nx test twenty-server`
- [x] `npx nx run twenty-server:lint`
