How do we use zkgroup?

[Atomic-Bean]

I've been trying to figure this out over the past few days and I managed to get it yesterday, but then I deleted the zkgroup file so I could rebuild a fresh one and write instructions to submit in a PR, but now signal-cli refuses to see the zkgroups stuff even when I put the same file back in the same place, I don't understand what's happening.

Here are the instructions I made, is there anything I'm missing/getting wrong?

### Use a release build

- Go to https://github.com/signalapp/zkgroup/releases and choose the release of your choice. Download the source code and the "lib" file for your platform (`dll` for Windows, `.so` for Linux and `dylib` for MacOS)
- Place the lib file at `zkgroup/ffi/java/src/main/java/org/`
- Create a zip of the `org` directory and rename it to `zkgroup-java-[VERSION].jar` where `[VERSION]` is in the format `x.y.z`
- Place the jar in `signal-cli/src/main`

### Use the latest build

- Clone the repo and select the branch you wish to build
- Install rust if you haven't already
- Follow the "Setup" part in `OVERVIEW.md`
- Skip the gradlew step and instead make your build, the commands are
	- `make android_so	# Multiple android platform builds`
	- `make server_so	# Unknown linux GNU`
	- `make mac_dylib	# MacOS`
	- TODO: What do we do for Windows/dll and iOS?
- Your lib file will be under `zkgroup/ffi/java/src/resources/` copy it to `zkgroup/ffi/java/src/main/java/org/`
- Create a zip of the `org` directory and rename it to `zkgroup-java.jar`
- Place the jar in `signal-cli/src/main`

To be clear, I only ever saw it working with the latest build/master + 0.7.1 release dylib file (Because of that version mismatch, that's why I wanted to rebuild it)

The command I've been running to test if it works is signal-cli -u +XXXXXXXXX updateProfile --name [NAME] --avatar [PATH]

[Atomic-Bean]

I've realised there's a similar jar in signal-cli/build/install/signal-cli/lib for version 0.7.0 (The signal-cli script checks this file). However that jar contains an .so whereas I need to use .dylib. I tried adding the v0.7.0 .dylib to the jar, but I get the error Error loading state file: org/signal/zkgroup/InvalidInputException when running the updateProfile command. But even if it worked, I feel like that would be the incorrect way to fix this problem.

[AsamK]

I think the cleanest way to solve this is to remove the bundled libzkgroup from the zkgroup-java-*.jar. then java will search for the library in the system library path.

I've created a wiki page to document this, feel free to extend it ... I don't have a mac to test it:
https://github.com/AsamK/signal-cli/wiki/Provide-native-lib-for-libsignal

[Atomic-Bean]

Thanks for the info, I didn't know you could do just make libzkgroup.

I've managed to get libzkgroup working again! Although I had an issue with one part. I don't think signal-cli sets java.library.path so instead it should default to the system/java path/s, however I wasn't able to figure out what my paths are. In the end I had to modify the signal-cli script itself with

MY_JAVA_LIBRARY_PATH="-Djava.library.path=/Users/USERNAME/Documents/libs"
exec "$JAVACMD" "$MY_JAVA_LIBRARY_PATH" "$@"

And that ended up working. I'd prefer to use the default java.library.path, but this is fine for me at least. Also I used the 0.7.0 dylib from the zkgroup releases since signal-cli's jar is v0.7.0.

Thanks again for that information and I'll update it with a few notes later today 👍

[Atomic-Bean]

Figure out how to check java.library.path and am now using the default instead. I've updated the wiki page with that information. Thanks again for the help and your work on signal-cli :)