Adding OpenSSL Support for Android

The Qt installation package comes with OpenSSL support, but the OpenSSL libraries are not part of the package due to legal restrictions in some countries. If your application depends on OpenSSL, consider packaging the SSL libraries with your Application Package (APK or AAB) as the target device may or may not have them.

You can use the QSslSocket::supportsSsl() static function to check for SSL support on the target device. First, include the header:

#include <QSslSocket>

Then use the following line to check if SSL is supported:

qDebug() << "Device supports OpenSSL: " << QSslSocket::supportsSsl();

Check Qt Creator's Application Output section or the Android logcat for that log message.

Adding OpenSSL Libraries

Using the convenience OpenSSL for Android repository, you can directly include OpenSSL libraries in your own project.

With CMake, add the following to your CMakeLists.txt:

if (ANDROID)
    include(FetchContent)
    FetchContent_Declare(
        android_openssl
        DOWNLOAD_EXTRACT_TIMESTAMP true
        URL https://github.com/KDAB/android_openssl/archive/refs/heads/master.zip
    )
    FetchContent_MakeAvailable(android_openssl)
    include(${android_openssl_SOURCE_DIR}/android_openssl.cmake)
endif()

Or if you cloned the repository into a subdirectory:

include(<path/to/android_openssl>/android_openssl.cmake)

Then, add the libraries to your targets:

qt_add_executable(your_target_name ..)
qt_add_executable(your_second_target_name ..)

if (ANDROID)
    add_android_openssl_libraries(your_target_name your_second_target_name)
endif()

For qmake, add the following to your .pro file:

android: include(<path/to/android_openssl/openssl.pri)

Alternatively, to add extra libraries, such as libcrypto and libssl. For CMake, use:

set_target_properties(<target_name> PROPERTIES
    QT_ANDROID_EXTRA_LIBS "<path_to_libs_dir>/libcrypto_3.so" "<path_to_libs_dir>/libssl_3.so"
)

Or for qmake use:

ANDROID_EXTRA_LIBS += \
    <path_to_libs_dir>/libcrypto_3.so \
    <path_to_libs_dir>/libssl_3.so

Using Qt Creator, it is possible to add extra libraries. For more information, see Qt Creator: Adding Libraries to Projects.

Building OpenSSL for Android

The following instructions guide you to build the OpenSSL libraries manually:

1. Download OpenSSL sources.
2. Extract the sources to a folder and navigate to that folder using the CLI.

   Note: If your development platform is Windows, you need msys with perl 5.14 or later to build OpenSSL.

3. Add the Android LLVM toolchain to your path, for example, for Linux use:

   export PATH=~/Android/Sdk/ndk/26.1.10909125/toolchains/llvm/prebuilt/<host>/bin:$PATH

   The Android SDK is commonly installed by Qt Creator or Android Studio in the following locations:

   • Linux: ~/Android/Sdk/
   • macOS: ~/Library/Android/sdk/
   • Windows: C:\Users\<USER>\AppData\Local\Android\Sdk\
4. Configure the OpenSSL sources to build for Android using the following command, where <arch> can take a value of: arm, arm64, x86 or x86_64:

   ./Configure shared android-<arch> -D__ANDROID_API__=26

   Note: You must consider enabling or disabling the SSL features based on the legal restrictions in the region where your application is available. For more information about the configurable features, see OpenSSL Configure Options.

5. Without a suffix, Android loads the system libraries libcrypto.so and libssl.so. These may be different versions from your libraries or from what Qt expects. To ensure that Qt apps can load the manually built OpenSSL libraries, run the following commands:

   make -j$(nproc) SHLIB_VERSION_NUMBER= build_libs
   
   mkdir -p ${out_path}
   cp libcrypto.so ${out_path}/libcrypto_3.so
   cp libssl.so ${out_path}/libssl_3.so
   
   cd ${out_path}
   patchelf --set-soname libcrypto_3.so libcrypto_3.so
   patchelf --set-soname libssl_3.so libssl_3.so
   patchelf --replace-needed libcrypto.so libcrypto_3.so libssl_3.so

   Note: Though the libcrypto and libssl shared libraries that are not versioned, they will have a _3 suffix.

   Then set the environment variable in your main.cpp file:

   qputenv("ANDROID_OPENSSL_SUFFIX", "<custom_suffix>");

   Note: Android does not load versioned libraries.