Android-PRNG is a sample Android NDK project to demonstrate two topics. First, it shows you how to compile a shared object using the Crypto++ library on Android. Second, it shows you how to sample sensors to accumulate seed data to use with a software based random number generator.

The project requires the Crypto++ library built for Android with architectures armeabi-v7a, arm64-v8a, x64 and x86_64. The project looks for them in the following locations based on architecture:

• /usr/local/cryptopp/android-armeabi-v7a
• /usr/local/cryptopp/android-arm64-v8a
• /usr/local/cryptopp/android-x86
• /usr/local/cryptopp/android-x86_64

You can create the prerequisites by repeatedly building and installing the Crypto++ library. The steps for the task are:

git clone https://github.com/weidai11/cryptopp.git
cd cryptopp
cp -p TestScripts/setenv-android.sh .
source ./setenv-android.sh armeabi-v7a

make -f GNUmakefile-cross distclean
make -f GNUmakefile-cross static dynamic
sudo make install PREFIX=/usr/local/cryptopp/android-armeabi-v7a

Lather, rinse, and repeat for each architecture.

Once you have the libraries installed, use ndk-build to build the library:

cd Android-PRNG
ndk-build

After the native libraries are built, use ant to build the APK and install it on a device:

ant debug install

Once installed, you should find it in the App Launcher.

References

The following references from the Crypto++ wiki should be helpful.

• http://www.cryptopp.com/wiki/Android_(Command_Line)
• http://www.cryptopp.com/wiki/Android.mk_(Command_Line)
• http://www.cryptopp.com/wiki/Android_Activity
• http://www.cryptopp.com/wiki/Wrapper_DLL