From 8980a8e42d94ab7c0bc9739283d39f938f8402b0 Mon Sep 17 00:00:00 2001 From: Christophe Besson Date: Mon, 7 Sep 2026 17:46:33 +0200 Subject: feat(mnp)!: seal the upload under the group key MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Downloads have been encrypted under a GEK-derived key since the beginning: `file_chunk` and `stream_data` both go through `chunk_ciphertext`. Uploads never were. `file_upload` carried the filename and the raw bytes in plain msgpack, and `file_upload_ack` carried the name the node stored them under — so the same file was ciphertext leaving a node and plaintext arriving at one. There was no threat model behind that asymmetry. Both halves now travel sealed under a third groupbox purpose, HKDF(GEK, info="meshbay:upload:v1"). The filename, the destination folder and the bytes are all inside the seal; only `upload_id` and `chunk_index` stay in clear, because the node routes and orders on them before it can decrypt. This direction seals *towards* the node — it holds the GEK for its own group — and it opens the payload before it picks a destination or touches the disk. What that forced, and why none of it is optional: - `filename` was the correlation key on both sides. It cannot be: matching an ack to its request by name would hand back exactly what the seal hides. `upload_id` replaces it — client-drawn, opaque to the node, unique within a connection, never an authorization input. The property it guarded (one refusal fails one upload, not every upload in flight) is unchanged. - Refusals can no longer quote what they refused. `No directory named 'X'` becomes `No such directory in this group` plus the `code` that was already there; the client knows what it sent. - No plaintext fallback. A path that still accepts plaintext is not a sealed path, so an unsealed `file_upload` is refused with `upload_not_sealed`. Hardened while here, because what comes out of a seal is authenticated but not validated — a member can seal anything: `filename` and `data` have their types checked before any upload state is created, and `chunk_index`/`total_chunks`, which are outside the seal by necessity, can no longer raise where a refusal was meant. Tests. `test_upload_sealed.py` pins the node half: nothing identifying on the wire, tamper/wrong-key/wrong-group all refused with nothing written, and multi-chunk reassembly unchanged. `test_upload_seal_client.py` drives the shipped `uploadFile` over the shipped `crypto.js` under node and feeds its real frames to the real `_do_file_upload` — the file lands intact, and the ack the node actually produced comes back with the name it chose for a collision, which is the half a source-reading test cannot see. Both upload purposes join the JS/Python groupbox parity vectors. BREAKING CHANGE: MNP 2.0. `file_upload`/`file_upload_ack` change shape on the wire every deployed client speaks, which is MAJOR by the same rule 1.0 was — but the break is confined to uploads. `MNP_MIN_SUPPORTED` stays at "1.0", so a 1.x peer still connects, browses, downloads, streams and chats; only its uploads are refused, with a message saying which side is old. The client checks the node's version before sending a chunk, so neither side meets this as a timeout. This is the version negotiation shipped in 1.0 earning its keep: 1.0 cost a flag day, 2.0 costs a refusal code. Co-Authored-By: Claude Opus 5 Claude-Session: https://claude.ai/code/session_01AsoWC3GmhNdwVFomW3QjH3 --- packages/meshbay-node/tests/test_root_writable_policy.py | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'packages/meshbay-node/tests/test_root_writable_policy.py') diff --git a/packages/meshbay-node/tests/test_root_writable_policy.py b/packages/meshbay-node/tests/test_root_writable_policy.py index 7eb75fd..8345880 100644 --- a/packages/meshbay-node/tests/test_root_writable_policy.py +++ b/packages/meshbay-node/tests/test_root_writable_policy.py @@ -21,13 +21,14 @@ anything. A deprecated instruction that still works is not deprecated, and this one would reopen uploads group-wide. """ -import base64 from pathlib import Path import pytest from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey +from conftest import sealed_upload from meshbay_common.adminop import OP_ROOT_UPDATE, OP_ROOT_EJECT, OP_ROOT_PLUG +from meshbay_common.crypto import generate_gek from meshbay_common.protocol import MNP from meshbay_node.indexer.group_index import GroupIndex from meshbay_node.roots import RootSet @@ -47,6 +48,8 @@ def _session(tmp_path: Path, user_id: str, *, "index": index, "sk_node": index.sk_node, "node_user_id": operator, + # Uploads are sealed under the group key since MNP 2.0. + "gek": generate_gek(), } session = WebRTCPeerSession.__new__(WebRTCPeerSession) session._ctx = ctx @@ -61,11 +64,8 @@ def _session(tmp_path: Path, user_id: str, *, def _upload(session, filename="clip.mp4", body=b"bytes"): - session._do_file_upload({ - "filename": filename, "dir": "shared", - "chunk_index": 0, "total_chunks": 1, - "data": base64.b64encode(body).decode(), - }) + session._do_file_upload(sealed_upload( + session, filename=filename, data=body, dir="shared")) def _uploads_dir(session) -> Path: -- cgit v1.2.3