zkp-android

Overview

zkp-android is an Android application that demonstrates Noir Zero-Knowledge Proof (ZKP) generation and verification. The project is built with the mopro toolchain, which generates cross-platform bindings from Rust source code to Kotlin (Android) via UniFFI and JNA.

Set up

All tooling is managed with devbox and the Makefile. Enter the dev environment first:

devbox shell

Then install the toolchain (srs_downloader, mopro-cli) and build the native bindings:

devbox run setup   # equivalent to: make setup

Download the SRS for each circuit and copy it into the Android assets:

Important

The app will not work without this step. Proof generation and verification require the structured reference string (SRS) for each circuit. The SRS files are large and are not committed to git, so you must download them yourself before running the app.

devbox run download-srs   # equivalent to: make download-srs

Finally, open the Android project in Android Studio:

studio android/

Update bindings

After changing the Rust source, regenerate the Kotlin bindings:

mopro build --auto-update   # build + copy into android/
# or, to copy existing bindings only:
mopro update

Update the circuits from zkp-pocs

The Noir circuits live in the zkp-pocs submodule. To rebuild them and copy the compiled circuit JSON into this project (both test-vectors/noir/ and android/app/src/main/assets/), run:

devbox run circuits   # equivalent to: make circuits

This initializes the submodule, runs devbox run circuits inside zkp-pocs (which compiles the circuits), and copies the resulting *.json files into place.

Warning

After updating the circuits, the on-device proofs will fail. The proof inputs are hard-coded in the Android code, so a regenerated circuit no longer matches them. You must update the hard-coded inputs to match the new circuit before proofs will succeed again.

Test

Run the Rust tests (the JNA jar is downloaded automatically if missing):

devbox run test   # equivalent to: make test