This crate contains Uniffi based bindings for the matrix-sdk-crypto crate. The
README mainly describes how to build and integrate the bindings into a Kotlin
based Android project, but the Android specific bits can be skipped if you are
targeting an x86 Linux project.
To build and distribute bindings for iOS projects, see a dedicated page
To build the bindings Rust will be needed it can be either installed using an OS specific package manager or directly with the provided installer.
The Android NDK will be required as well, it can be installed either through Android Studio or directly using an installer.
First we'll need to install the Rust target for our desired Android architecture, for example:
# rustup target add aarch64-linux-android
This will add support to cross-compile for the aarch64-linux-android target, Rust supports many different targets, you'll have to make sure to pick the right one for your device or emulator.
After this is done, we'll have to configure Cargo to use the correct linker
for our target. Cargo is configured using a TOML file that will be found in
%USERPROFILE%\.cargo\config.toml on Windows or $HOME/.cargo/config on Unix
platforms. More details and configuration options for Cargo can be found in the
official docs over here.
[target.aarch64-linux-android]
ar = "NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin/ar"
linker = "NDK_HOME/toolchains/llvm/prebuilt/linux-x86_64/bin/aarch64-linux-android30-clang"
To enable cross compilation for olm-sys which builds our libolm C library
we'll need to set the ANDROID_NDK environment variable to the location of our
Android NDK installation.
$ export ANDROID_NDK=$HOME/Android/Sdk/ndk/22.0.7026061/
The bindings can built for the aarch64 target with:
$ cargo build --target aarch64-linux-android
After that, a dynamic library can be found in the target/aarch64-linux-android/debug directory.
The library will be called libmatrix_crypto.so and needs to be renamed and
copied into the jniLibs directory of your Android project, for Element Android:
$ cp ../../target/aarch64-linux-android/debug/libmatrix_crypto.so \
/home/example/matrix-sdk-android/src/main/jniLibs/aarch64/libuniffi_olm.so
These crates are built with the Rust language version 2021 and require a minimum compiler version of 1.62.