fix(hub): the pepper and a device key take the passphrase, not a token

POST /me/bundle-pepper (was GET) and POST /users/devices require auth_key.
A refreshed or lifted token could otherwise fetch the pepper, or register a
device whose every sign-in carries it. Both callers have just been given the
passphrase.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

4 files changed, 67 insertions, 12 deletions

diff --git a/packages/meshbay-hub/tests/test_account_deletion.py b/packages/meshbay-hub/tests/test_account_deletion.py
index a31aaff..632c133 100644
--- a/packages/meshbay-hub/tests/test_account_deletion.py
+++ b/packages/meshbay-hub/tests/test_account_deletion.py
@@ -140,7 +140,8 @@ async def test_deletion_clears_device_keys(client, db_session):
         select(User.id).where(User.username == "devicer_test"))).scalar_one()
 
     r = await client.post("/v1/users/devices", headers=headers,
-                          json={"pk_auth_ed25519": _device_pk(), "label": "desktop"})
+                          json={"pk_auth_ed25519": _device_pk(), "label": "desktop",
+                                "auth_key": _auth_key(password, "devicer_test")})
     assert r.status_code == 201, r.text
 
     # Present before, or the emptiness asserted below proves nothing.
@@ -166,15 +167,19 @@ async def test_a_new_account_can_reuse_the_deleted_accounts_device(client):
     """
     pk = _device_pk()
     token, password = await _register(client, "firstlife")
-    r = await client.post("/v1/users/devices", json={"pk_auth_ed25519": pk},
+    r = await client.post("/v1/users/devices",
+                          json={"pk_auth_ed25519": pk,
+                                "auth_key": _auth_key(password, "firstlife")},
                           headers={"Authorization": f"Bearer {token}"})
     assert r.status_code == 201, r.text
     await client.request("DELETE", "/v1/users/me",
                          headers={"Authorization": f"Bearer {token}"},
                          json={"auth_key": _auth_key(password, "firstlife")})
 
-    token2, _ = await _register(client, "secondlife")
-    r = await client.post("/v1/users/devices", json={"pk_auth_ed25519": pk},
+    token2, password2 = await _register(client, "secondlife")
+    r = await client.post("/v1/users/devices",
+                          json={"pk_auth_ed25519": pk,
+                                "auth_key": _auth_key(password2, "secondlife")},
                           headers={"Authorization": f"Bearer {token2}"})
     assert r.status_code == 201, r.text
 
diff --git a/packages/meshbay-hub/tests/test_bundle_pepper.py b/packages/meshbay-hub/tests/test_bundle_pepper.py
index be9da19..6c9f63d 100644
--- a/packages/meshbay-hub/tests/test_bundle_pepper.py
+++ b/packages/meshbay-hub/tests/test_bundle_pepper.py
@@ -57,7 +57,8 @@ async def test_a_device_sign_in_gets_it_too(client):
     login = await _login(client, "pepper_dev")
     sk = Ed25519PrivateKey.generate()
     r = await client.post("/v1/users/devices", headers=_bearer(login["access_token"]),
-                          json={"pk_auth_ed25519": pk_to_b64(sk.public_key()), "label": ""})
+                          json={"pk_auth_ed25519": pk_to_b64(sk.public_key()), "label": "",
+                                "auth_key": KEY})
     assert r.status_code == 201
     ts = int(time.time())
     sig = sk.sign(f"meshbay:user_auth:pepper_dev:{ts}".encode())
@@ -88,23 +89,51 @@ async def test_it_is_in_no_token(client):
     assert not any("pepper" in k for k in claims)
 
 
+async def _ask(client, token, auth_key=None):
+    body = {} if auth_key is None else {"auth_key": auth_key}
+    return await client.post("/v1/users/me/bundle-pepper", headers=_bearer(token), json=body)
+
+
 @pytest.mark.asyncio
-async def test_an_open_session_may_ask_and_a_node_may_not(client):
+async def test_a_session_asks_with_the_passphrase_and_a_node_may_not(client):
     from test_node_scope_not_admin import _node_token
     await _register(client, "pepper_node")
     login = await _login(client, "pepper_node")
 
-    r = await client.get("/v1/users/me/bundle-pepper", headers=_bearer(login["access_token"]))
+    r = await _ask(client, login["access_token"], KEY)
     assert r.status_code == 200
     assert r.json()["bundle_pepper"] == login["bundle_pepper"]
 
     node = await _node_token(client, "pepper_node", login["access_token"])
-    r = await client.get("/v1/users/me/bundle-pepper", headers=_bearer(node))
+    r = await _ask(client, node, KEY)
     assert r.status_code == 403
     assert login["bundle_pepper"] not in r.text
 
 
 @pytest.mark.asyncio
+async def test_a_token_alone_never_gets_it(client):
+    """
+    Not a refreshed one, not the one sign-in handed out: a token is what a page
+    holds, and a pepper beside the bundles an operator keeps is the offline
+    passphrase oracle again. Two calls — refresh, then ask — must not add up
+    to what a refresh is refused.
+    """
+    await _register(client, "pepper_bare")
+    login = await _login(client, "pepper_bare")
+    refreshed = (await client.post("/v1/users/token/refresh",
+                                   json={"refresh_token": login["refresh_token"]})).json()
+
+    for token in (login["access_token"], refreshed["access_token"]):
+        bare = await _ask(client, token)
+        wrong = await _ask(client, token, "w" * 44)
+        assert bare.status_code == 422
+        assert wrong.status_code == 403
+        assert login["bundle_pepper"] not in bare.text + wrong.text
+    assert (await client.get("/v1/users/me/bundle-pepper",
+                             headers=_bearer(login["access_token"]))).status_code in (404, 405)
+
+
+@pytest.mark.asyncio
 async def test_it_is_sealed_at_rest_and_bound_to_its_account(client, db_session):
     await _register(client, "pepper_rest")
     login = await _login(client, "pepper_rest")
@@ -157,7 +186,7 @@ async def test_it_is_never_logged(client):
     try:
         await _register(client, "pepper_log")
         login = await _login(client, "pepper_log")
-        await client.get("/v1/users/me/bundle-pepper", headers=_bearer(login["access_token"]))
+        await _ask(client, login["access_token"], KEY)
     finally:
         root.removeHandler(grab)
         root.setLevel(saved[0])
diff --git a/packages/meshbay-hub/tests/test_device_auth.py b/packages/meshbay-hub/tests/test_device_auth.py
index f9b172e..04012ee 100644
--- a/packages/meshbay-hub/tests/test_device_auth.py
+++ b/packages/meshbay-hub/tests/test_device_auth.py
@@ -46,10 +46,11 @@ async def _account(client, username="alice_test") -> str:
     return resp.json()["access_token"]
 
 
-async def _register_device(client, token: str, pk: str, label: str = ""):
+async def _register_device(client, token: str, pk: str, label: str = "",
+                           auth_key: str = "k" * 44):
     return await client.post(
         "/v1/users/devices",
-        json={"pk_auth_ed25519": pk, "label": label},
+        json={"pk_auth_ed25519": pk, "label": label, "auth_key": auth_key},
         headers={"Authorization": f"Bearer {token}"})
 
 
@@ -275,3 +276,22 @@ async def test_the_hub_states_a_minimum_client_version(client):
     assert resp.status_code == 200
     client_floor = resp.json()["client"]
     assert client_floor["minimum"] and client_floor["recommended"]
+
+
+async def test_a_session_alone_cannot_register_a_device(client):
+    """
+    A registered key signs in with no passphrase for as long as it stays, and
+    each of those sign-ins carries the bundle pepper. So a token — refreshed,
+    or lifted from a page — must not be enough to add one: the passphrase is.
+    """
+    token = await _account(client)
+    sk, pk = _device()
+
+    bare = await client.post("/v1/users/devices", json={"pk_auth_ed25519": pk},
+                             headers={"Authorization": f"Bearer {token}"})
+    wrong = await _register_device(client, token, pk, auth_key="w" * 44)
+
+    assert bare.status_code == 422
+    assert wrong.status_code == 403
+    assert (await client.post("/v1/users/auth",
+                              json=_sign(sk, "alice_test"))).status_code == 401
diff --git a/packages/meshbay-hub/tests/test_password_reset.py b/packages/meshbay-hub/tests/test_password_reset.py
index b07f77c..f285c1d 100644
--- a/packages/meshbay-hub/tests/test_password_reset.py
+++ b/packages/meshbay-hub/tests/test_password_reset.py
@@ -159,7 +159,8 @@ async def test_reset_revokes_sessions_and_wipes_devices(client, db_session):
     sk = Ed25519PrivateKey.generate()
     dev = await client.post(
         "/v1/users/devices",
-        json={"pk_auth_ed25519": pk_to_b64(sk.public_key()), "label": "laptop"},
+        json={"pk_auth_ed25519": pk_to_b64(sk.public_key()), "label": "laptop",
+              "auth_key": "erin_test" + "a" * 40},
         headers={"Authorization": f"Bearer {token}"})
     assert dev.status_code == 201, dev.text