crypto23

crypto23 is a modern C++23, header-only implementation of Rijndael (including AES variants).

What this library does

• Provides a templated crypto23::rijndael<BlockMode, KeyMode> implementation.
• Includes convenient aliases for AES block mode:
  • crypto23::aes_128
  • crypto23::aes_192
  • crypto23::aes_256
• Supports compile-time and runtime encryption/decryption APIs.
• Works on contiguous byte-like buffers (std::array, std::vector, std::string, std::span, etc.).

Requirements

• C++23 compiler
• CMake 3.31+

Add to your project

Option 1: add_subdirectory

add_subdirectory(path/to/crypto23)
target_link_libraries(your_target PRIVATE crypto23::crypto23)

Option 2: install + find_package

After installing crypto23, use:

find_package(crypto23 CONFIG REQUIRED)
target_link_libraries(your_target PRIVATE crypto23::crypto23)

Usage

#include <array>
#include <cstddef>
#include <crypto23/rijndael.h>
#include <string>

int main() {
	constexpr auto key = std::array{
		std::byte{0x2b}, std::byte{0x7e}, std::byte{0x15}, std::byte{0x16},
		std::byte{0x28}, std::byte{0xae}, std::byte{0xd2}, std::byte{0xa6},
		std::byte{0xab}, std::byte{0xf7}, std::byte{0x15}, std::byte{0x88},
		std::byte{0x09}, std::byte{0xcf}, std::byte{0x4f}, std::byte{0x3c}
	};

	// Runtime API
	std::string message = "Hello, World!";
	auto encrypted = crypto23::aes_128::encrypt(message, key);
	auto decrypted = crypto23::aes_128::decrypt(encrypted, key);

	// Compile-time friendly API for string literals
	constexpr auto encrypted_literal = crypto23::aes_128::encrypt_string("Hello, World!", key);
	auto decrypted_literal = crypto23::aes_128::decrypt_string(encrypted_literal, key);

	return (decrypted_literal == "Hello, World!" && decrypted.size() == message.size()) ? 0 : 1;
}

API at a glance

• encrypt_string / decrypt_string: string-literal focused helpers.
• encrypt_buffer / decrypt_buffer: fixed-size buffer helpers.
• encrypt / decrypt: generic contiguous range helpers.

All helpers apply padding so plaintext size does not need to be block-aligned.

Security notes

• The current API encrypts blocks independently (ECB-style behavior).
• For production-sensitive data, prefer a mode with IV/nonce and authentication (for example, GCM or CTR + MAC) at a higher layer.
• Always use unpredictable keys and keep them out of source control.

Running tests

cmake -S . -B build -DBUILD_TESTING=ON
cmake --build build
ctest --test-dir build --output-on-failure

Contributing

Contributions, bug reports, and feature requests are welcome. Open an issue or submit a pull request.

1. Fork it
2. Create your feature branch: git checkout -b feature/my-new-feature
3. Commit your changes: git commit -am "Add some feature"
4. Push to the branch: git push origin feature/my-new-feature
5. Submit a pull request

License

This project is licensed under the MIT License.