README.md

AES - Lightweight Single Header AES C++ Library

This repository contains a single header file C++ that provides AES encryption and decryption function that supports both a pure C++ implementation and optimized implementations that leverage hardware acceleration technologies such as; AES-NI for x86-64 architectures and ARM NEON for ARM architectures.

Important

This library focuses solely on the encryption and decryption of AES blocks and does not include padding functions or block cipher encryption modes.

You need to code additional functions or incorporate libraries to handle padding and encryption modes such as CBC or CTR.

Here is a CLI program for File Encryption that uses some of the modules that I wrote (AES, BytePadding, BlockCipherModes) which can be used as an example.

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Requirement

Requires C++17 so you need to compile it with the compilation flag -std=c++17.

Enable Portable C++ AES Implementation

By simply including the main header file (AES.hpp), the code will be compiled using portable C++. Make sure to compile with the optimization flag -O3.

Please note that the portable code is slower than the two alternatives mentioned below.

Additional Compiler Flag: -D USE_CXX_AES

CMake: AES_IMPL=portable

Enable AES-NI Hardware Acceleration

To achieve a significant speed-up performance, add the following flag when compiling for x86-64 architecture.

e.g. mid-range PCs & Laptops.

Additional Compiler Flag: -D USE_INTEL_AESNI -maes

CMake: AES_IMPL=aesni

Enable ARM neon Hardware Acceleration

To gain a speed-up performance, add the following flag when compiling for aarch64, armv8 architecture.

e.g. modern android devices.

Additional Compiler Flag: -D USE_NEON_AES -march=armv8-a+crypto

CMake: AES_IMPL=neon

Sample Program

/*    sample.cpp    */
#include <iostream>
#include "AES.hpp"

int main()
{
    unsigned char data[16] = {
      0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77,
      0x88, 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff,
    };

    unsigned char key[] = {
      0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
      0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
    };

    Cipher::Aes<128> aes(key);
    aes.encrypt_block(data); // data is now encrypted.
    aes.decrypt_block(data); // data is now decrypted.
}

Encrypted Value:

0x69, 0xc4, 0xe0, 0xd8, 0x6a, 0x7b, 0x04, 0x30,
0xd8, 0xcd, 0xb7, 0x80, 0x70, 0xb4, 0xc5, 0x5a,

Compiling with CMake

To build with cmake while choosing what AES implementation to use, you can add the following cmake code below into your CMakeLists.txt file.

cmake:

cmake_minimum_required(VERSION 3.16)

project(YourProjectName VERSION 1.0.0)

# ...

# add this block before `add_executable`
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED True)

set(AES_IMPL "aesni" CACHE STRING "Choose an AES Implementation")
set_property(CACHE AES_IMPL PROPERTY STRINGS auto portable aesni neon)
# add this block before `add_executable`

# ...

add_executable(main Source.cpp)

# ...

# add this block to after `add_executable(...)`
if("${AES_IMPL}" STREQUAL "aesni")
    target_compile_definitions(main PUBLIC USE_INTEL_AESNI)
    if(MSVC)
        target_compile_options(main PRIVATE /arch:SSE2)
    else()
        target_compile_options(main PRIVATE -maes)
    endif()
elseif("${AES_IMPL}" STREQUAL "neon")
    target_compile_definitions(main PUBLIC USE_NEON_AES)
    target_compile_options(main PRIVATE -march=armv8-a+crypto)
elseif("${AES_IMPL}" STREQUAL "portable")
    target_compile_definitions(main PUBLIC USE_CXX_AES)
endif()
# add this block to after `add_executable(...)`

Then run cmake-gui choose which aes implementation you want to enable in the check-boxe of AES_IMPL.

Or use the terminal command for bash/cmd`.

cmake -S . -B . -D AES_IMPL=<CHOSEN_AES>
cmake --build . --config Release

The value of <CHOSEN_AES> could be aesni, neon or portable, .

Compiling in the Command Line

1. compile with [pure c/c++ code]

g++ -o sample.exe sample.cpp -D USE_CXX_AES -O3

2. comple with [AES-NI]

g++ -o sample.exe sample.cpp -D USE_INTEL_AESNI -maes -O3

3. comple with [Arm-NEON-AES]

g++ -o sample.exe sample.cpp -D USE_NEON_AES -march=armv8-a+crypto -O3