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crystr | Compile-Time Strings and Numbers Encryption for C++20

Description

This repository provides a compile-time strings and numbers encryption mechanism based on xor bitwise operations using mathematical operations at compile-time in order to make the strings and numbers challenging to decompile.
Users can easily encrypt their strings using the crystr macro provided in the header, and numbers using crynum and crynum_long.
The repository includes an example demonstrating the usage of crystr, crynum and crynum_long to use encrypted strings and numbers.
It's recommended, but not necessarily, to disable the optimization under C/C++ -> Optimization -> "Optimization" and "Whole Program Optimization"
When using the virtual functions option it needs RTTI OFF (Run-Time Type Information under C/C++ -> Language (/GR-))

Key Aspects

• The xor key is generated by mathematical operations based on a uniqueid that is different every time the program is compiled and for each encrypted string/number.
• The uniqueid is an hash based on the date, time and a counter which increases every time a string/number encrypts: const_hash(__DATE__ __TIME__) + __COUNTER__ * __COUNTER__.
• When using crystr every character is encrypted with a different xor key based on the index of the character inside the string.
• It is possible to choose between virtual and inline functions to decrypt the strings/numbers.
• If using the virtual implementation it works well with crycall (see the repo).
• All the variables used to retrieve the xor key are thread_local, meaning they're stored as (NtCurrentTeb()->ThreadLocalStoragePointer + TlsIndex)->x_var, making it more challenging to decompile and not ready-pastable from decompiler tools such as ida or ghidra.
• The string is never copied but instead it's being written on, in order to prevent unwanted decrypted copies of the string in memory.
• The decrypted string can be re-encrypted at any time using the built-in encrypt function.
• The decrypted/encrypted string/number can be removed from memory at any time using the built-in clear function.
• The string/number will show as never referenced in most common decompiler tools such as ida or ghidra see (How it shows).
• Compatible with char[], wchar_t[], int, __int64, unsigned int, unsigned __int64, float, double.
• Supports C++20 and higher versions.

How it shows

Look here
How it shows using inline functions option

Repository Structure

• include/: Contains the crystr.hpp header file providing the compile-time string/number encryption mechanism.
• src/: Holds the example main.cpp file showcasing the usage of crystr, crynum, crynum_long.
• LICENSE: Licensing information for the provided code.
• README.md: Documentation explaining how to use everything.

Usage Example

The repository includes an example demonstrating the usage of the crystr, crynum, crynum_long macros:

main.cpp

//#include "crycall.hpp" // see https://github.com/Android1337/crycall for an all-potential virtual implementation
#include "crystr.hpp"

int main() {
    auto encrypted_str = crystr("Hello, this is an encrypted string!");
    printf("Decrypted String: %s\n", encrypted_str.decrypt());
    encrypted_str.clear();

    auto encrypted_int = crynum(1234);
    printf("Decrypted Int: %d\n", encrypted_int.decrypt());
    encrypted_int.clear();

    auto encrypted_double = crynum_long(1.234);
    printf("Decrypted Double: %f\n", encrypted_double.decrypt());
    encrypted_double.clear();

    return 0;
}