leftp / Compile-time-hash-functions

Compile time hash functions

Description

This is an implementation for md5, sha1 and sha2 (all version). It can be used to generate a hash at compile time, such that the binary file will have the hash but not the original string. It can also be used at runtime.

Supports C++11/14/17/20

Classes

In all classes the type T should be either const char * or a primitive type. std:string can be used at runtime only (for c++ versions below 20). For any other type it will just hash the value of the pointer.

C++11/14

* MD5<T>(T value)
* SHA1<T>(T value)
* SHA224<T>(T value)  
* SHA256<T>(T value)
* SHA384<T>(T value)
* SHA512<T>(T value)
* SHA512_224<T>(T value)
* SHA512_256<T>(T value)

If T is const char * (string literal) than the following classes can also be used:

* MD5String(T value)
* SHA1String(T value)
* SHA224String(T value)  
* SHA256String(T value)
* SHA384String(T value)
* SHA512String(T value)
* SHA512_224String(T value)
* SHA512_256String(T value)

C++17/20

Same as older versions but without the T. e.g. MD5(T value)

Operators supported

==, !=, [], << (ostream)

The subscript operator treats the hash as an array of 32 bit integers

Example

 #include <iostream>

 #include "compile_time_hash.hpp"
 
 using namespace std;
 
 //constexpr must be used here
 constexpr SHA256 hash_value = SHA256("Hello World");
 
 int main() {
   cout << hash_value << endl;
 }

prints: a591a6d40bf420404a011733cfb7b190d62c65bf0bcda32b57b277d9ad9f146e

The string "Hello World" will not appear in the final binary.

Usage with CMake

If you want to use CMake in your project, you can include this library in two ways:

As a submodule

1. Add this repository as a git submodule: git submodule add https://github.com/abbbaf/Compile-time-hash-functions.git
2. Include this code in your CMakeLists.txt:

   add_subdirectory(Compile-time-hash-functions)
   target_link_libraries(YOUR_TARGET compile_time_hash)

3. Include it in your .cpp file:

   #include <compile_time_hash.hpp>

Install it globally

1. Clone this repository somewhere: git clone https://github.com/abbbaf/Compile-time-hash-functions.git
2. Install it into the global include directory:
3. Add this to your CMakeLists.txt:

   find_package(compile_time_hash REQUIRED)
   target_link_libraries(CTH_test_2 compile_time_hash::compile_time_hash)

4. Include it in your .cpp file:

   #include <compile_time_hash/compile_time_md5.hpp>