From 2ccb6653e8841d4d6f3ab933f84746cce4e2fe2b Mon Sep 17 00:00:00 2001 From: Christophe Besson Date: Sat, 26 Sep 2026 02:03:50 +0200 Subject: feat(protocol): bind the MNP token to the node it is for (E10) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The audience split stopped a member's node credential from opening the hub API. It did not stop the credential being *replayed to another node*: the MNP token carried the member's whole group set and named no node, so a token handed to node A's operator could be presented to node B the member also belongs to. That does not read content on B — the handshake still requires proving node B's group key, which the operator lacks — but it reaches B's pre-proof window and fetches the member's *encrypted* keypair bundle for B (offline-attackable, bounded, audited): a disclosure §2.4 says should not follow from hosting a member on A. The token now names the node it is minted for (a `node` claim = that node's Ed25519 key), and authorize_token refuses one that names a different key. The client already knows the target node's key (from /v1/groups/{id}/nodes) and asks for a token bound to it: POST /v1/nodes/mnp-token takes node_pk, and transport.connect threads it (group-page, the connection pool and rewrap pass n.pk_node; reconnect preserves it). A token that names no node is still accepted, because the hub only mints one for the authenticated requester, so an unbound token grants nothing across accounts — which also keeps non-binding callers working with no churn. Done before deploy, so it folds into the MNP 4.0 flag day rather than needing its own. Docs: §5.2, register E10, MESHBAY_NODE_PROTOCOL.md §6.3. test_handshake.py and test_mnp_token.py hold the binding (a token for node A is refused by node B, accepted by node A; an unbound token still works); red before, green after. common/node/hub suites green. Co-Authored-By: Claude Opus 4.8 --- packages/meshbay-hub/src/meshbay_hub/auth.py | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'packages/meshbay-hub/src/meshbay_hub/auth.py') diff --git a/packages/meshbay-hub/src/meshbay_hub/auth.py b/packages/meshbay-hub/src/meshbay_hub/auth.py index e182ba0..0d0fd95 100644 --- a/packages/meshbay-hub/src/meshbay_hub/auth.py +++ b/packages/meshbay-hub/src/meshbay_hub/auth.py @@ -241,7 +241,7 @@ def issue_access_token( def issue_mnp_token(user_id: str, groups: list[str] | None = None, - ttl: int = 900) -> str: + node_pk: str | None = None, ttl: int = 900) -> str: """Issue the short-lived token a member presents to a node in the handshake. `aud=MNP_AUD`, so it is accepted by `authorize_token` and refused by the hub @@ -249,6 +249,11 @@ def issue_mnp_token(user_id: str, groups: list[str] | None = None, lifetime does not interrupt a long transfer or a film already playing; only a fresh connection or a reconnect needs a fresh one. It carries the same `sub`/`groups`/`jti` the node authorises and denylists on. + + `node` names the node this token is for (its base64 Ed25519 key), so it + cannot be replayed to another node the member also belongs to — the node + checks it in `authorize_token` (E10). The client knows the target node's key + before it connects and asks for a token bound to it. """ if _hub_sk_pem is None: raise RuntimeError("Hub keypair not loaded") @@ -260,6 +265,7 @@ def issue_mnp_token(user_id: str, groups: list[str] | None = None, "iat": now, "exp": now + ttl, "groups": groups or [], + "node": node_pk or "", "scope": "user", "aud": MNP_AUD, } -- cgit v1.2.3