227c098da7871efb3200588e54672a35f0d8e79d
4
Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
 Paul HittandClaude Opus 4.8
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ee17d773b7 |
A session we ANSWER can now be v3, and receive failures say why
`E2ESession.respond` hard-coded `version = if (pq == null) 1 else 2`, so
a session this device answered could never be v3 — while `initiate`
twelve lines above correctly returns 3 whenever the post-quantum ratchet
is on. A conversation iOS started therefore ran as v3 on one side and v2
on the other, and every message this device sent into it was refused by
the peer as a downgrade (§13.4) and dropped on arrival. iOS to Android
worked; Android to iOS did not, for as long as the pairing existed.
Kotlin talking to Kotlin never noticed, because both ends drive the
ratchet from their own PQ state and ignore the label. Only a peer that
enforces the version sees it. `HybridSessionTest` asserted the wrong
value — `assertEquals(2, bobSide.version)`, two lines below requiring
the initiator to be 3 — so the suite passed while encoding the defect.
Corrected, with the reason recorded next to it.
The version now follows the initiator rather than assuming 3 whenever PQ
is present: a v2 peer sends a PQ block too, and answering that in v3
breaks the pairing in the other direction.
Receive-side failures are no longer swallowed. `catch (_: Exception) {}`
threw away the reason for every undecryptable envelope, which left this
half of every delivery investigation unreadable — the relay says
delivered, the app shows nothing, and the one place that knew why
discarded it. The envelope is still skipped; it now names the id, the
device and the exception. Sends report the protocol shape they emit, and
receives report which of the three chains opened them.
Also here:
- proguard-rules.pro, which did not exist while build.gradle.kts
referenced it. R8 accepts a missing entry in silence, so release
builds ran on the platform defaults and answering a call aborted the
process inside WebRTC's JNI_OnLoad — it resolves Java classes by
name, and R8 had renamed them. The build now fails if the file is
missing rather than shipping without it.
- Server refusals read as sentences. `RelayException.Http` had no case
in `describe()`, so choosing a taken handle showed "relay returned
409:" and a JSON fragment, which says nothing about picking another
name. Transport failures showed a Java networking string naming an
address the person never typed.
- Switching between signing in and creating an account clears the last
error. It belonged to the other mode and stayed on screen, so taking
the advice it gave looked like it had failed.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Paul Hitt
|
eaf860e794 |
Advertise v3, now that there is evidence for the claim
PROTOCOL_VERSION read 2 with a note saying 3 would be wrong until ML-KEM was in
every ratchet step, "a separate piece of work". That work is done and proven
against another engine, so the number moves in the same change as the evidence
rather than ahead of it.
Until now the ratchet was inert in the field: iOS advertises 3 and gates on the
peer doing the same, so an iOS-to-Android session negotiated v2 and no message
ever carried a ratchet step, whatever either engine implemented.
🔴 A version is a claim other devices act on. Peers pin the highest proven
version and the pin is monotonic (§13.4), so a build that advertises 3 and
cannot honour it does not degrade — it strands every contact that believed it.
Three tests moved with it, and one is new. `a v2 registration publishes the
whole block` asserted 2 and now asserts the constant. `a capability signature
does not transfer between versions` edited a bundle to `proto = 3` to prove the
signature would not follow — a hardcoded neighbour that stopped testing anything
the moment the engine published 3, so it uses `PROTOCOL_VERSION + 1`. The v2
gating test needed a peer that has genuinely proven 2, which this engine no
longer produces: `copy(proto = 2)` is not enough, because the capability
signature commits to the version, so `publishedV2` re-signs for it.
The new one checks the published bundle claims 3 AND proves it. Bumping the
constant without the signature following would produce a bundle every peer
silently reads as v1, with nothing reporting an error anywhere.
Also: `the sealed blob reveals nothing` was the same coin flip as its iOS twin —
sealing ids 41 and 42 and searching the BASE64 for "41" and "42", about a 14%
chance of a meaningless failure. It fired during this run. The iOS one was fixed
this morning and this was missed because only one engine was looked at.
606 tests, 0 failures. Cross-engine: 56 passed, 0 failed.
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Paul HittandClaude Opus 4.8
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1e96af0122 |
A v2 peer was being sent a post-quantum ratchet step
Proving the v3 ratchet across engines turned up a bug in shipping it, and this one would have broken every existing Android conversation. `E2ESession.initiate` turned the v3 ratchet on whenever the peer offered a PQ prekey. Every v2 device offers one — offering a prekey is a claim to §12, not to §13. So a build with this change would attach `pqdh`/`pqct` to messages for 0.6, the released build, whose ratchet has no post-quantum anything. That fails twice over, which is why it would have looked like a network problem. Their root step derives without `ss` and under the `_v1` info string while ours used `_v3`, so the keys diverge; and their canonical header omits the two fields, so the AAD does not match either. The first message never opens and never would. Gated on a PROVEN claim now, the way the iOS engine already does it: `chosen != null && bundle.proto >= 3`. `bundle.proto` on its own is the relay's word for it, but `chosen` is non-null only when the capability signature over that same proto verified (§12.7), so the pair is a claim the peer actually made. The test asserts on the absence of a header field, which is the only way to catch this — every message still decrypts in a self-test, because both sides of one engine agree with each other about the mistake. The interop driver now publishes a real v3 bundle: `pqspk` under `FlamenetE2E_PQSPK_v2`, and `caps_sig` over `FlamenetE2E_Caps_v2 ‖ uint8(3)`. Both were needed before the web engine would negotiate anything but v1 — which is why the harness had been quietly proving v1 and nothing else. It can still publish a v1 bundle on request, because the fleet still holds devices that speak it and that coverage must not disappear the day v3 lands. 605 tests, 0 failures. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> |
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Paul HittandClaude Opus 4.8
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444ebf0862 |
Post-quantum key agreement on Android
A session is post-quantum only when both ends are, so with every Android device registering `proto: 1` the iPhone implementation protected approximately no real conversation. The property was true of the code and false of the product. This is the other half. ML-KEM-768 over Bouncy Castle's low-level `pqc.crypto.mlkem`, the same way Ed25519 already uses its `rfc8032` class: not the JCA provider, which is awkward to register on Android and which R8 cannot shrink. The platform offers nothing here — Conscrypt has no ML-KEM at any API level — and hand-rolling a lattice KEM to avoid a dependency would be a far worse trade than the one Ed25519 already made. No new dependency: the jar was already in the build for Ed25519. Keys are stored as the 64-byte FIPS 203 seed, never the expanded decapsulation key — 64 bytes in the vault instead of 2400, and the same representation iOS persists, which is what lets a history export cross platforms. That is also the thing most likely to be silently wrong, so it is checked against the published vector rather than against another run of our own code: the seed in `pqx3dh-v2.json` derives the public key the normative JavaScript engine derived, and the full responder side reproduces the published session key and associated data byte for byte. Everything else here would pass with an implementation that is internally consistent and agrees with nobody. Negotiation refuses in three places, and each is a substitution somebody would otherwise get for free. A KEM prekey whose signature does not verify is treated as ABSENT, so a relay handing out a key of its own drops the session to v1 rather than to its key — the same substitution `spk_sig` stops classically, and worth more here because it buys the whole post-quantum half. A `proto` claim with no `caps_sig` reads as v1, so a relay cannot advertise a v2 device as v1-only and strip the post-quantum half off every new session. And the one-time id is signed big-endian and inside the signature, so a renumbered key falls back to the last-resort one instead of being spent. Both pools are refilled together, and that is not tidiness. They drain at the same rate — one key per new session — so a refill that topped up only the classical pool would let the post-quantum one run dry and push every later session onto the last-resort key, every one of them sharing a single KEM key, with nothing anywhere reporting a downgrade. Mixed fleets work in both directions and a spent prekey is not an error: a duplicate delivery of a v2 prekey envelope names a one-time key this device has already consumed, and throwing there would turn a retransmission into a dead conversation. Two test fixtures had to say what they are rather than answer by order. Sending now asks for a transparency-log head on its own, so a queue matched purely by position handed that request the device listing and failed on a parse error nowhere near the cause. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com> |