meshbay.git/packages/meshbay-hub/src/meshbay_hub/static/keyderive.js, branch 0.2

feat!: identity keys per node — C4's blast radius drops to one operator

2026-08-14T15:51:48Z

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

perf(client): bundle KDF to 128 MB, and derive it once per sign-in

2026-08-14T12:25:44Z

Argon2id memory 64 → 128 MB. Memory is the lever, not time: it caps how many guesses a card can hold at once, so the ceiling on one high-end GPU moves from roughly 4k to roughly 2k guesses/s and its 24 GB fits ~187 lanes instead of ~375. Measured through the vendored build: 640 ms, against 322 ms at 64 MB. While measuring the real cost of a sign-in, found the SPA deriving the bundle key twice — once for the key pair kept for the session, then again inside decryptBundle() for the local bundle. At these parameters that is 0.6 s of pure waste. Measured now, end to end: auth_key (PBKDF2 600k) 239 ms bundle v1 (PBKDF2 600k) 240 ms legacy, until every bundle is upgraded bundle v2 (Argon2id 128MB) 650 ms ----------------------------------- sign-in 1 129 ms (889 ms once no v1 bundles remain) Once per sign-in, and only then: reopening a group, downloading, streaming and reloading the page all reuse the key, which lives in IndexedDB from login. Also bounds two waits in the node's hub WebSocket, found because the node went silent again mid-deploy. It had reconnected after the hub restart, sent its auth frame, and waited for a reply that never came — `ws.recv()` had no timeout, so a hub that accepts a socket and then says nothing for a few seconds while starting up parks the task forever: node running, logging nothing, invisible to everyone. The auth exchange now times out at 15 s, connect at 15 s, and a refused auth retries with a fresh token instead of ending the task for good. QE harness signs in once per account and reuses the token — several clients there stand for several browsers of one person, and what tells them apart is which keys they hold, not which token, while the hub quite rightly rate-limits repeated logins from one address. Tests: 341, plus the live workflow. Co-Authored-By: Claude Opus 5

feat(client): Argon2id for the keypair bundle, and remove the backup toggle

2026-08-14T10:42:51Z

Two corrections to yesterday's judgement, in the order they matter. **The toggle is gone.** Asked to make the remote key backup optional, I shipped a setting whose "off" position meant: no second browser, ever, and clearing your storage destroys the account. I wrote the warning that says so without drawing the conclusion. A control whose only effect is to break the ordinary case is not a control, and removing an exposure by removing the feature is not a fix. Every browser backs its keys up again, unconditionally. **The exposure is fixed where it actually lives: the KDF.** The keypair bundle rests on every node whose group its owner joins, protected by the passphrase alone (finding C4). It used PBKDF2-SHA512 at 600k — compute-only, which is exactly what a GPU eats. Measured on this machine: PBKDF2 600k costs 241 ms and Argon2id 64 MB/t=3 costs 322 ms, near enough the same honest work, except only one of them forces an attacker to find 64 MB per guess. So the bundle key is now Argon2id 64 MB / t=3 / p=1, via a vendored WebAssembly build (no external host — the CSP forbids one, and 12.2 will tighten it further). Parameters chosen by measurement through that build: 19 MB is OWASP's floor at 118 ms, 256 MB is 1.3 s and too slow for a phone, 64 MB sits where a login should. What this buys, stated honestly: cracking a bundle yields the owner's identity keys, and with them content on OTHER nodes and the ability to sign as them — not the content on the operator's own node, which they host in the clear by design. Argon2id raises that price steeply; it does not remove it, and a weak passphrase still loses. Hence the floor raised to 12 characters and ~60 bits in the same breath, which can only be enforced client-side: with the password split (T1) the hub never sees a passphrase. Migration is automatic and invisible. Bundles carry an "MBK2" marker; the old form is still readable, and is re-encrypted the first time a browser backs it up. Both keys are derived at sign-in, because which one a bundle needs is only known once it is read and the passphrase is deliberately not kept around. Two implementations of the KDF now exist — the browser's WASM and argon2-cffi in QE — so a parity test holds them byte-identical. A disagreement would not look like an error; it would look like an account nobody can open. keypair_bundle_delete stays, without a UI. It is the mechanism behind withdrawing your data from a node, exercised end to end, and it will belong to a deliberate "forget me on this node" action rather than a setting that quietly disables multi-device. Verified against the live deployment: the full workflow passes, including recovering keys on a second client from the passphrase alone. Tests: 341. Co-Authored-By: Claude Opus 5

fix(node): group isolation, upload confinement, GEK seizure, admin challenge

2026-08-13T08:43:16Z

Phase 11.5 — findings H1, C5a, H2, C5b, H5 (see second-review.md). Batched together because the node-side changes share webrtc_server.py and cannot be separated into working commits. H1 — cross-group chat leak. chat_store, the peer registry and the display-name cache were read from the shared transport context, and daemon.py hoisted the FIRST group's chat store onto it. On a node hosting several groups every group's messages went to one database, chat_history served them back to members of every other group, and chat broadcast reached all peers regardless of group. All three now resolve through _group_ctx(). C5a — upload confinement. Uploads landed in the shared root under a client-chosen name and overwrote whatever was there. Any member could destroy the operator's files, and by becoming the recorded uploader of the replaced file could then delete it through the uploader path, bypassing the Ed25519 admin challenge. Uploads now go to a per-user quarantine (.uploads/{user_id}/), refuse to overwrite, and enforce chunk ordering, a filename allowlist and a size cap. H2 — stored XSS in the node admin UI. Filenames chosen by any group member were interpolated raw into the localhost UI, which has no authentication, so script execution there equals control of the node admin API. Now html.escape() throughout, textContent in the audit table, plus CSP/nosniff/no-referrer. The CSP contains exfiltration but cannot stop injected inline script — escaping is the fix. C5b — group key seizure. gek_bundle_store wrote whatever any member sent and auto-activated bundles addressed to the node operator. The operator's X25519 public key is public (the node publishes it in handshake_ack), so any member could wrap a key of their choosing for it and take over the group, locking every legitimate member out. Storing now requires an operator signature and _try_activate_gek is removed: nothing arriving over MNP can set a live GEK. H5 — unbound signing oracle. The node challenged with 32 raw random bytes and the client signed them blind, so a signature named no operation, subject, node or time. New meshbay_common/adminop.py defines a length-prefixed, domain-separated transcript; both sides build it independently and the client refuses to sign when the announced op/subject do not match its request. BREAKING: a group admin who does not operate the node can no longer store GEK bundles on it. Invites must be performed by the node operator. Adds tests/test_security_regressions.py. Verified against pre-fix source via git stash. Three pre-existing tests asserted the vulnerable behaviour as a feature and were inverted: gek auto-activation, and the transport-wide chat_store in test_daemon. Tests: 109 node, 132 hub+common. Co-Authored-By: Claude Opus 5

feat: Phase 12 — P2P crypto material, password split, node Ed25519 auth

2026-08-13T01:56:30Z

Baseline commit capturing in-progress Phase 12 work that was already present in the working tree (uncommitted) before the Phase 11.5 security remediation begins. Committed as-is, without review or modification, so that remediation changes arrive as a separable diff. Contents: BundleStore (P2P GEK + keypair bundles), password split (auth_key / bundle_key), node Ed25519 auth (POST /v1/nodes/auth, node-scoped JWT), GEK-HMAC handshake proof with DTLS channel binding, Ed25519 admin challenge-response, node local admin UI rewrite, browser key persistence. Not authored in this session — captured to establish a baseline. Co-Authored-By: Claude Opus 5

feat: password-based key derivation + operational QUICKSTART

2026-08-09T12:50:22Z

keyderive.py: derive Ed25519+X25519 from username+password via Argon2id. Same credentials → same keys on any device. Encrypt/decrypt keypair bundle (AES-256-GCM) for hub storage (web clients). 7/7 tests. Full suite: 81/81. keyderive.js: browser counterpart using PBKDF2-SHA512 + random keypairs encrypted for hub storage. Avoids algorithm mismatch with Python. hub/models.py + users.py: keypair_bundle field added to User, stored on registration, returned in login response for web client key recovery. QUICKSTART.md: fully rewritten. 3 operational scripts in QE/demo-v1/: setup_demo.py — create accounts, group, distribute GEK run_node.py — start HTTP node (watches shared/ directory) download.py — bob login → GEK fetch → decrypt → save All tested locally end-to-end. No invented URLs. Co-Authored-By: Claude Sonnet 4.6 (1M context)