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hashlib

Cra3z' hashlib is a C++11 header-only hash algorithm library which like Python's hashlib.

supported algorithms:

• md5
• sha1
• sha224
• sha256
• sha384
• sha512
• sha3_224
• sha3_256
• sha3_384
• sha3_512

Usage

Using headers

hashlib is a header-only library, so you can simply copy the headers in the directory include/hashlib to where you need it. However, it is recommended to embed hashlib as a subproject in your project, or install it first and then import it via CMake's find_package.

find_package(hashlib REQUIRED)
target_link_libraries(<your-target> hashlib::hashlib)

Single header

You can also generate a single header hashlib.hpp which combines all headers in the directory include/hashlib, see Generate single header.

Using C++20 module

hashlib supports C++20 module (need the standard module std); you can generate the module file, and then import it, see Generate C++20 module.

import std;
import hashlib;

int main() {
    hashlib::md5 md5;
    md5.update("hello world");
    std::println("{}", md5.hexdigest());
}

Building & Installation

Requirements

• CMake 3.22+ (for building)
• C++ compiler which supports C++11 or newer standard

mkdir <your-build-dir>
cd <your-build-dir>
cmake -S . -B <your-build-dir>
cmake --build <your-build-dir>
cmake --install <your-build-dir> --prefix <your-install-dir>

CMake Options

Option	Default	Description
HASHLIB_TESTS	ON	enable tests
HASHLIB_BUILD_SINGLE_HEADER	OFF	generate single header
HASHLIB_BUILD_MODULE	OFF	generate C++20 module

Generate single header

using the following command, the single header hashlib.hpp which combines all headers in the directory include/hashlib will be generated in your build directory.

cmake -S . -B <your-build-dir> -DHASHLIB_BUILD_SINGLE_HEADER=ON

Generate C++20 module

using the following command, the module file hashlib.cppm will be generated in your build directory.

cmake -S . -B <your-build-dir> -DHASHLIB_BUILD_MODULE=ON

using conan package manager

You can also install hashlib by conan package manager.

conan install --requires=hashlib/[*]

Examples

• get md5 of a string by using hashlib::md5

#include <iostream>
#include <hashlib/md5.hpp>

int main() {
    hashlib::md5 md5{std::string("hello world")};
    std::cout << md5.hexdigest() << '\n'; // 5eb63bbbe01eeed093cb22bb8f5acdc3
}

• using the method update or operator<<

#include <iostream>
#include <hashlib/md5.hpp>

int main() {
    {
        hashlib::md5 md5;
        md5.update(std::string("hello"));
        md5.update(std::string(" world"));
        std::cout << md5.hexdigest() << '\n'; // 5eb63bbbe01eeed093cb22bb8f5acdc3
    }
    {
        hashlib::md5 md5;
        md5 << std::string("hello") << std::string(" world");
        std::cout << md5.hexdigest() << '\n'; // 5eb63bbbe01eeed093cb22bb8f5acdc3
    }
}

• hashing the bytes from iterators and ranges whose elements are char, unsigned char, signed char or std::byte (since c++17)

#include <iostream>
#include <hashlib/sha1.hpp>

int main() {
    unsigned char data[] = {0x00, 0xff, 0x55, 0xaa, 0x12, 0x34, 0x56, 0x78};
    hashlib::sha1 sha1;
    sha1.update(data);
    std::cout << sha1.hexdigest() << '\n'; // f9d9a450e6e14895936f8dc796e30209528de337
}

#include <iostream>
#include <fstream>
#include <hashlib/sha1.hpp>

int main() {
    std::ifstream file("example.txt", std::ios::in | std::ios::binary);
    if (!file) {
        std::cerr << "Failed to open file" << std::endl;
        return EXIT_FAILURE;
    }
    hashlib::sha1 sha1;
    sha1.update(
        std::istreambuf_iterator<char>{file}, 
        std::istreambuf_iterator<char>{}
    );
    std::cout << sha1.hexdigest() << '\n'; // output the sha1 digest of the file example.txt
}