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2 Commits
Author SHA1 Message Date
Paul HittandClaude Opus 5 5f983c1455 Android: the app, and the two things only a phone could tell us
There is now a Flamenet Messenger app that installs, launches, creates an
account on a self-hosted relay, registers a device, publishes prekeys, and
stores all of it in an Android Keystore-backed vault. Verified on an emulator
through the actual screens, not by unit test.

92 JVM tests, 37 cross-engine, 9 on-device, 3 against live relays.

Two findings, both of which the JVM suite was structurally incapable of
producing.

**Android has no ordinary Ed25519 provider.** `KeyPairGenerator.Ed25519` and
`KeyFactory.Ed25519` come from `AndroidKeyStore` and from nowhere else -- probed
on API 35 rather than assumed -- and Keystore only makes keys it keeps. Every
Ed25519 key in this engine is one we must hold: a device identity in our own
vault, an account key derived from a passphrase. So the JCA route could never
have worked. It compiled, passed 81 tests on a laptop, and threw "Not
initialized" on the first launch on a phone. Worse, it was LATENT: a wrong
password failed before any key was minted, so the error path worked perfectly
while the happy path was broken.

Ed25519 now uses BouncyCastle's `math.ec.rfc8032` core directly -- the engine's
one real dependency, present because the platform leaves a hole, and a strictly
better answer than the non-constant-time keygen it replaces. ProviderProbeTest
records the measurement so nobody guesses again.

**The prekey field is `prekeys`, not `opks`.** I guessed. The relay accepted the
registration, returned 200, and stored nothing -- so the device was published
and could not be started with, a failure with no error anywhere. Caught by a
live test against the throwaway fleet, which exists because the same path
through the emulator takes four minutes to say "timed out" and nothing about
where.

Two testing traps, recorded where they bite:

An indeterminate progress spinner animates for ever, so Compose's test clock
never goes idle and `waitUntil` never evaluates its condition -- it fails on the
full timeout, reading as "sign-up is broken" when sign-up works. Auto-advance is
now disabled around the wait only; disabling it for the whole test is the next
mistake, because the app opens on a spinner while it reads the vault.

Wiping the Keystore in `@Before` deletes the key the already-launched activity
is holding, and every later write fails against a key that no longer exists. The
test signs out through the UI instead, which is both safe and what a person does.

Failure messages now include what the screen was showing. A bare timeout sends
you to the network, the relay and the crypto in turn while the app has been
displaying the reason the whole time.

Also corrects a note that said this Mac had no Android SDK. It does.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-23 17:02:16 -04:00
Paul HittandClaude Opus 5 fc93df24e6 Kotlin: Ed25519, and cross-engine interop against the web engine
The seventeen Kotlin tests that landed with X3DH and the ratchet prove the
engine agrees with itself. That is not the property anyone needs. Two engines
written by the same person agree about the same misreadings of the spec, and
every one of those shows up months later as "the message will not decrypt" on
someone else's phone. So this wires the Kotlin engine up against the web
engine, which is normative, in both directions.

23 assertions, all passing: v1 X3DH both ways, identical associated data,
alternating ratchet turns past the handshake, out-of-order and permanently
lost messages, a drained one-time prekey pool, tamper rejection, safety
numbers, and the canonical transparency-log leaf.

Three things worth recording.

Ed25519 was missing, and the engine could derive an account address but never
sign a claim for one. The JCA offers no route from a private EdDSA key to its
public half, so the RFC 8032 keygen is done here -- and verified against the
RFC 8032 test vectors, not against a round-trip through our own code. A
round-trip proves only that the file agrees with itself, and every wrong clamp,
endianness and sign convention agrees with itself perfectly. The scalar
multiplication uses BigInteger and is therefore not constant-time; it runs once
at sign-in, in the user's own process, and signing deliberately stays with the
platform provider.

The harness reports a build failure as a failure, never a skip. The Swift
harness beside it once printed "skipped" -- which reads as green -- while
silently building a different checkout. Only a missing JDK skips here, and the
resolved path is printed either way.

Each section is wrapped so a divergence is a named failure rather than a crash.
That was not theoretical: breaking the Kotlin message-key derivation on purpose
crashed the process with a stack trace and skipped every later section. It now
reports four failing sections and finishes the run. The negative control is how
this was checked at all -- a suite that passes on its first run and has never
been seen to fail is not evidence of anything.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-08-23 15:04:35 -04:00