8b719032c260346b941a11230e13c3169a4d0029
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Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Paul HittandClaude Opus 5
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fdd1ab7ee7 |
Multi-homing: keep a mailbox at more than one relay
Federation let somebody at another relay write to you. It did not stop your relay being the only place your mail lives — so relay1 going away took the undelivered messages with it, and relay1 refusing to serve you locked you out of your own inbox. That is the gap people actually mean by decentralised, and it is what this closes. An account registers the same devices, with the same identity keys, at several relays and publishes a signed record naming them. A sender fans out to every one. Any single relay can then be unreachable, hostile or gone and the message still arrives, because it was never only there. The record is signed by the ACCOUNT key, not asserted by a relay. A relay that could edit the list would drop the others from it and become the sole delivery target, which is precisely the position multi-homing exists to escape. A sending relay verifies against the key the recipient's address decodes to — the address IS the key — so it never has to trust what the relay it asked handed back. The serial closes the half a signature does not. An OLD list is genuinely signed: a relay could serve one from before a second home was added and it would verify perfectly. Records may only move forward, and the test proves the real attack rather than a forgery — publish serial 2, then replay the still validly signed serial 1, and get a 409. Envelopes carry a client-chosen id, identical in every copy, so a recipient polling two relays sees one message rather than two. Nullable and not unique: an envelope from an older client has none and must still be delivered, and two rows legitimately share an id when one message goes to two devices. `maxHomes` is 4 because a sender fans out to every entry, and a signed record naming a thousand hosts would turn any sender's relay into an amplifier aimed wherever the signer likes — with a signature making it look legitimate. Verified on relay1/2/3.flamenet.io: 12 checks. Alice names only relay2, her relay discovers relay3 from the signed record, and Bob reads the message from either. Local suite 255. ⚠️ Delivery to an unreachable home is reported and NOT retried. A home that is down when you send simply misses that message; closing that needs a queue and this does not have one. ⚠️ Neither app calls any of this yet. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> |
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Paul HittandClaude Opus 5
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6f83248e1c |
Give an account an identity no server issued
A relay's `user_id` is a row number it assigned itself, and the account service's pseudonym is HMAC'd per product precisely so two services cannot correlate their users. Neither survives a trip to a second relay, so nothing addressed by either can cross a relay boundary — which is the first thing federation needs, and the reason a deleted relay currently takes its users' names with it. So identity becomes a key the client derives and holds: Ed25519, stretched from the passphrase under `flamenet/account/identity/v1`, alongside the per-product keys that already work this way. The public half, Crockford base32, is the address. Derived rather than generated, so the same passphrase reproduces the same fnid on a device that never held it — re-register the same key at a new relay and contacts who pinned it are still talking to the same person. Relay: `users.account_key` / `users.fnid` (unique in the database, not just in the handler), `POST /e2e/account/identity` to claim by proving possession, and `GET /e2e/account/identity/:handle` to resolve. The claim signature binds the audience, the local user id and the key itself; dropping any one of the three lets a claim be replayed at another relay, lifted onto another account here, or transplanted onto another key. Verification uses the very key being registered, so the relay confirms possession and never acquires an opinion about whose key it is. Rotation is refused rather than silently overwritten — a new address strands every contact that pinned the old one, and that needs a migration record they can follow. Log leaves go v1 -> v2, binding a subject instead of a row number: `fnid:<b32>` where an account has enrolled, `local:<audience>/<user_id>` where it has not. The fallback is qualified rather than bare because a device can be registered before its key is claimed, and the alternatives were worse in both directions — skipping those devices leaves a hole in the one record that must not have holes, and logging them unqualified produces leaves that mean different things depending on origin with nothing in the leaf to say so. This is not a server-side change. All three engines hash the leaf and two of them verify it against the relay, and a published vector pins the exact bytes, so the format moves in one commit or not at all. Existing v1 leaves keep their hashes and are backfilled to a self-describing `legacy-v1/` subject: the log is append-only, and a format change is not a licence to rewrite history. The version prefix sits inside the hashed bytes so a v1 leaf recomputed under v2 rules fails rather than verifying against a different subject. Green: engine conformance 80, relay §8 suite 235 (10 new), JS<->Swift interop 74, Kotlin published vectors. Two things found on the way, neither addressed here: - iOS never calls `enforceKeyLog`. It and `requireKeyLog` are both declared in E2EInbox and nothing reads either, so §19 is dead code on that client while the JS one wires it. The subject is threaded through ready for a caller. - `engine/test/interop/build.sh` prefers ~/Code/flamenetmessenger over the checkout it is run from, so in a worktree it silently builds the wrong sources and reports a *skip* rather than a failure. Set FNMSG_APP_DIR. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> |
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Paul HittandClaude Opus 5
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85f6a29953 |
Kotlin: X25519, with the small-order check that is not optional here
Raw 32-byte keys on the wire, X.509 SubjectPublicKeyInfo in the JCA -- so every crossing needs the 12-byte DER prefix added or stripped. Written out as a constant rather than parsed: a DER parser here would be more code than the thing it parses, and one more place to get a length wrong. Refuses an all-zero shared secret. X25519 produces all zeros for a small-order peer key, and a peer that sends one forces both sides to a secret it already knows. RFC 7748 says implementations MAY check; when the peer's key arrives over a relay nobody trusts, MAY is not the right reading. All four small-order points from §6.1 are tested. ⚠️ XDH is API 33+ on Android. Older devices throw NoSuchAlgorithmException at the first call, and the app must either bundle a provider or refuse to run -- a decision nobody has made, so it is documented rather than papered over. ⚠️ These run on the JVM against SunEC. Android routes the same calls through Conscrypt. Passing here says the encoding is right and nothing about a device. Kotlin engine: 27 tests -> 33. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> |
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Paul HittandClaude Opus 5
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bff7a4bbdd |
Kotlin: HKDF-SHA256 and AES-256-GCM, against external vectors
Checked against RFC 5869 and NIST CAVP rather than against our JavaScript engine. An implementation validated only against our other implementation inherits our misunderstandings, and finding where the first two quietly agreed on something the spec does not say is the entire reason for writing a third. Three things pinned that a naive version gets wrong: - An empty HKDF salt means HashLen zeros, not "no HMAC key". SecretKeySpec throws on a zero-LENGTH key, so the naive version crashes on exactly the case the app uses -- §12 derives its per-context secrets with an empty salt. - 255 blocks is a hard ceiling. The counter is one byte; a naive loop wraps at 256 and silently returns key material it already returned. - The AEAD box is nonce || ciphertext || tag. CryptoKit's `combined` emits that layout and the JS engine assembles it by hand to match, so a box built any other way decrypts to garbage on the other engines rather than failing loudly. HKDF is hand-written on Mac rather than taken from a provider: Android's providers disagree about whether HKDF exists at all. Kotlin engine: 9 tests -> 27. ⚠️ Still JVM-only. These prove nothing about Android, where crypto goes through Conscrypt rather than the JVM's JCA, and nothing here has ever been compiled against the Android SDK. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> |
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Paul HittandClaude Opus 5
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e7862c0d95 |
Point the site and the harnesses at the four repositories
The relay and the Kotlin engine are published on their own now, so the self-hosting guide told people to clone a directory that no longer exists and the source page said everything was in one repository. Both pages list all four now, with what each is for. The self-hosting guide still only needs the first one -- the rest are there so that self-hostable is something a reader can check rather than something they are told. The Android vector loader hardcoded ../../engine/test/vectors, which is only right inside this repository. It resolves from a candidate list now, honours FLAMENET_VECTORS, and still FAILS rather than skips when it finds nothing: the entire value of a third engine is that it is checked against something other than a reading of our own code. Nine tests pass against the JDK in Homebrew, which is not on the default java_home path. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> |
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Paul HittandClaude Opus 5
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06b97ca69b |
Start Android with the engine, held to the published vectors
Android does not exist, and the first thing it needs is not a screen. It needs the protocol implemented a third time — which is only worth anything if the third implementation is checked against the spec and the published vectors rather than against a reading of our own Swift. So `android/engine` is a plain Kotlin/JVM library with no Android in it: no SDK, no emulator, no device, and therefore gateable in CI on Linux like everything else. It reads engine/test/vectors/protocol-v1.json from its one location rather than carrying a copy, because a vector transcribed into the test that checks it is a vector that agrees with itself. Covered so far: safety numbers (§7) and key transparency verification (§19) — RFC 6962 leaf and node hashing, the unbalanced split, and bottom-up audit paths. Nine tests, all green against the same file the JavaScript and Swift engines answer to. The §19 tests are the ones worth having. A top-down reading of a bottom-up audit path yields the correct root for every left-spine index, so it passes any suite that only checks index 0 — the vectors pin a right-descending index, and the tests assert both that the published path verifies and that the same path reversed does not. android/README.md lists what is missing — X25519, X3DH, the ratchet, sealed sender, both post-quantum halves, the relay client, the app — as a table rather than as an omission. Android stays honestly marked "not started" on the site until that list is shorter. Bytecode targets 17 without demanding a JDK 17 be installed: a jvmToolchain(17) fails on any newer JDK, which is a poor trade for a library with no JDK 17-specific behaviour. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> |