OpenSSL Hybrid Encryption Test

Test C++17 project for hybrid file encryption with OpenSSL:

• RSA key pair generation
• AES file encryption
• RSA encryption of the temporary AES key
• streaming file encryption/decryption

The application creates a small test file, encrypts it, decrypts it back, and writes the restored result.

Requirements

• CMake 3.24 or newer
• C++17 compiler
• On Windows: Visual Studio Build Tools or Visual Studio with the Desktop development with C++ workload

On Windows, CMakeLists.txt downloads a pre-built OpenSSL package with FetchContent and copies the required DLLs next to the executable.

Build

From the project directory:

cmake -S . -B build
cmake --build build --config Release

If you changed CMake options or headers and want a clean rebuild:

cmake --build build --config Release --clean-first

Run

With Visual Studio generators, the executable is usually in build\Release:

cd build\Release
.\crypto_app.exe

The program generates these files in the current working directory:

• private.pem
• public.pem
• important_data.txt
• important_data.enc
• restored_data.txt

Expected console output:

Generating RSA-4096 key pair...
Success! Saved 'private.pem' and 'public.pem'.
Encrypting file with public key...
Decrypting file with private key...
Done! Verify 'restored_data.txt' matching original inputs.

No output means the files match.

Notes

If CMake reports No CMAKE_CXX_COMPILER could be found, install Visual Studio Build Tools and enable the C++ desktop workload.

If the executable cannot find OpenSSL DLLs, rebuild the project so the post-build copy step can place the DLLs next to crypto_app.exe.