This app showcases the Supreme KMP Crypto provider on JVM, Android and on iOS. It is possible to generate key pairs, sign data, and verify the signature.

Generation of attestation statements is also supported, although on iOS, only P-256 keys can be attested due to platform constraints. The default JVM provider does not natively support the creation of attestation statements, so it is a NOOP there.

Except for the JVM (because there is no system-wide keystore), the app relies only on multiplatform code. Hence, everything is located in the common App.kt.
As can be seen, no activity passing and callbacks are required, even for biometric auth! Everything just works© automagically…

• check your system with KDoctor
• install JDK 17 on your machine
• add local.properties file to the project root and set a path to Android SDK there

To run the application on android device/emulator:

• open project in Android Studio and run imported android run configuration

To build the application bundle:

• run ./gradlew :composeApp:assembleDebug
• find .apk file in composeApp/build/outputs/apk/debug/composeApp-debug.apk

To run the application on iPhone device/simulator:

• Open iosApp/iosApp.xcproject in Xcode and run standard configuration
• Or use Kotlin Multiplatform Mobile plugin for Android Studio

Attestation and biometric auth is not supported on the simulator! Only Apple could fix this, but this is unlikely to ever happen.