From f0984e86d9cb596a282ce6feb7cfc2f075b2794b Mon Sep 17 00:00:00 2001 From: Christophe Besson Date: Fri, 14 Aug 2026 17:51:48 +0200 Subject: feat!: identity keys per node — C4's blast radius drops to one operator MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit One keypair was copied to every node its owner joined, so cracking the bundle on any single node yielded the identity used on all of them: their content on other operators' machines, and the ability to sign as them anywhere. That lateral reach was the part of C4 worth attacking. Each node now gets its own keypair, generated the first time its owner joins it and left with that node alone. An operator who cracks what sits on their own disk holds a key that is a stranger to every other node — and on their own node, one that unlocks nothing they did not already hold: they serve the content, the index and every byte of it by design. Nothing changes for the user. A first contact with a node already needed that operator's code, and the key is created in the same step; a second browser still recovers it from the node with the passphrase alone. Two operators can also no longer tell they host the same person by comparing keys. BREAKING, and deliberately without a compatibility path — the deployment is wiped for the next demo: - users.pk_ed25519 / pk_x25519 dropped (migration a7c31f9e40b2) - registration no longer sends or stores a key - PUT /v1/users/me/keys and regenerateKeys() gone; rotation is now `member unpin` plus a fresh code, decided on the machine that pinned it - /pubkeys returns an account id and a node's linking key. It was the directory H3 read, and nothing wraps for it any more - the pk_user JWT claim is gone That last one closed a live defect the inventory turned up: the node recorded pk_user as the uploader's identity and authorized deletion against it, so a hub issuing a token naming its own key could delete anyone's uploads on any node. Attribution now uses the key the node itself pinned. A simplification falls out. Registration generates nothing, so a scripted signup is a real account: `demo.py bootstrap` takes a wiped hub and node to a working demo with no browser, which was impossible while keys were born in one. Also fixes, found by running it on a wiped deployment: the key handed back on a join now belongs to the group the connection is for, not the group named in the invitation — an operator pairs node-wide but redeems the code while opening a group, and expects to read it. Tests: 343, including the two that state the property — a key pinned by one node is refused at another, and someone else's code does not admit it. Verified end to end against a wiped hub and node: bootstrap, pair, invite, join, download, stream, second browser, revoke. Design: docs/per-node-identity-v1.md Co-Authored-By: Claude Opus 5 --- packages/meshbay-hub/tests/test_hub_api.py | 21 ++++++++++++++++----- packages/meshbay-hub/tests/test_node_auth.py | 3 ++- packages/meshbay-hub/tests/test_node_ws_auth.py | 2 +- 3 files changed, 19 insertions(+), 7 deletions(-) (limited to 'packages/meshbay-hub/tests') diff --git a/packages/meshbay-hub/tests/test_hub_api.py b/packages/meshbay-hub/tests/test_hub_api.py index 7b75fd1..5a2cf86 100644 --- a/packages/meshbay-hub/tests/test_hub_api.py +++ b/packages/meshbay-hub/tests/test_hub_api.py @@ -144,8 +144,11 @@ async def test_jwt_offline_verify(client, hub_key_path): hub_pk_pem = r_pk.json()["pk_hub_pem"].encode() decoded = pyjwt.decode(token, hub_pk_pem, algorithms=["EdDSA"]) - assert decoded["pk_user"] == pk_ed assert "jti" in decoded # mandatory + # The token carries no user key. It used to, and the node recorded it as the + # uploader's identity — so whoever issued tokens decided who could delete a + # file. The hub certifies accounts; nodes pin keys. + assert "pk_user" not in decoded @pytest.mark.asyncio @@ -194,11 +197,17 @@ async def test_refresh_token_rotation_old_rejected(client): @pytest.mark.asyncio async def test_get_user_pubkeys(client): + """ + The endpoint resolves an account; it is not a key directory any more. + + Publishing user identity keys is what finding H3 exploited — the invite flow + wrapped the group key for whatever came back. Keys are now generated per node + and pinned there, so there is nothing here to substitute. + """ pk_ed, pk_x, _ = _gen_user_keys() await client.post("/v1/users/register", json={ "username": "frank", "email": "frank@example.com", - "password": "frankpass99", - "pk_user_ed25519": pk_ed, "pk_user_x25519": pk_x}) + "password": "frankpass99"}) login = await client.post("/v1/users/login", json={ "username": "frank", "password": "frankpass99"}) token = login.json()["access_token"] @@ -206,8 +215,10 @@ async def test_get_user_pubkeys(client): r = await client.get("/v1/users/frank/pubkeys", headers={"Authorization": f"Bearer {token}"}) assert r.status_code == 200 - assert r.json()["pk_ed25519"] == pk_ed - assert r.json()["pk_x25519"] == pk_x + body = r.json() + assert body["user_id"] and body["username"] == "frank" + assert "pk_ed25519" not in body, "user identity keys must not be published (H3)" + assert "pk_x25519" not in body, "user identity keys must not be published (H3)" # ── Nodes ───────────────────────────────────────────────────────────────────── diff --git a/packages/meshbay-hub/tests/test_node_auth.py b/packages/meshbay-hub/tests/test_node_auth.py index e629d20..72ce412 100644 --- a/packages/meshbay-hub/tests/test_node_auth.py +++ b/packages/meshbay-hub/tests/test_node_auth.py @@ -214,7 +214,8 @@ async def test_node_scope_allows_pubkey_lookup(client): r = await client.get("/v1/users/op4/pubkeys", headers={"Authorization": f"Bearer {node_token}"}) assert r.status_code == 200 - assert "pk_ed25519" in r.json() + # An account id and the node's linking key — no user identity keys (H3). + assert "pk_ed25519" not in r.json() assert r.json()["pk_node_ed25519"] is not None diff --git a/packages/meshbay-hub/tests/test_node_ws_auth.py b/packages/meshbay-hub/tests/test_node_ws_auth.py index def5e66..1391722 100644 --- a/packages/meshbay-hub/tests/test_node_ws_auth.py +++ b/packages/meshbay-hub/tests/test_node_ws_auth.py @@ -64,7 +64,7 @@ async def _announce_node(client, user: dict) -> str: def _node_token(user: dict) -> str: from meshbay_hub.auth import issue_access_token - return issue_access_token(user["user_id"], user["pk_ed"], scope="node") + return issue_access_token(user["user_id"], scope="node") @pytest.mark.asyncio -- cgit v1.2.3