Multi-module Android app, built bottom-up from a verifiable core. core-protocol is pure Kotlin/JVM (no Android SDK): SPKI-pinned control plane (enroll/profile/session over HttpsURLConnection — API-1 compatible, hostname verification off, trust is the pin), HKDF-SHA256 session keys, ELT1 UDP data plane (HMAC gate, ECHO+observation, MTU probe) — byte-compatible with the Go server. Unit tests incl. the RFC 5869 HKDF vector (key derivation provably matches the server). LiveServerTest + scripts/test-fmr.sh prove the client end-to-end against the deployed fmr server: profile (8 caps), session, ECHO rtt~11ms with the observation block returning our observed NAT port, MTU 1400->1400, observations. Live test self-skips without ECHOLOT_LIVE_*. Two client bugs caught live: java.net.http hostname verification (→ HttpsURLConnection, also the Android-minSdk-26 choice) and ECHO padding needed for the observation to survive anti-amplification. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Echolot app
The production Android client (spec). Native Kotlin + Jetpack Compose. Multi-module; built bottom-up from a verifiable protocol spine.
Modules
| Module | Type | Status |
|---|---|---|
core-protocol |
pure Kotlin/JVM | done — client half of probe-protocol.md, verified live against the server |
core-measurement |
pure Kotlin/JVM | planned — measurement-schema.md types |
core-probe |
Android lib | planned — app-tier probes, ported from echolot-prober |
core-shizuku |
Android lib | planned — dual-path executor (UserService + newProcess fallback) |
app |
Android app | planned — Compose UI |
core-protocol is deliberately Android-free so it builds and unit-tests on any JDK (no Android
SDK) and can run integration tests against a live server.
core-protocol
Implements the control plane (SPKI-pinned enrollment/profile/sessions via HttpsURLConnection —
Android-API-1 compatible, hostname verification off because trust is the pin), the HKDF-SHA256
session-key schedule, and the binary ELT1 UDP data plane (HMAC gate, ECHO + observation block,
MTU probe) — byte-compatible with the Go server.
./gradlew :core-protocol:test # unit tests (crypto vectors, wire round-trip)
scripts/test-fmr.sh # live end-to-end test against the deployed server
test-fmr.sh mints an enrollment token over SSH, enrolls via the public control plane, computes
the SPKI pin from the served cert, and runs LiveServerTest — proving the client speaks the wire
protocol to the real server (enroll → profile → session → echo+observation → MTU → observations).
The live test self-skips when ECHOLOT_LIVE_* env vars are absent, so unit runs and CI stay green
offline.