From c7d5bc5c86e361c2a2131056a47077979d193c3f Mon Sep 17 00:00:00 2001
From: Kawe Mazidjatari <48657826+Mauler125@users.noreply.github.com>
Date: Tue, 25 Jul 2023 01:06:21 +0200
Subject: [PATCH] Add XorStr header

For obfuscating string literals.
---
 r5dev/public/tier1/xorstr.h | 104 ++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 r5dev/public/tier1/xorstr.h

diff --git a/r5dev/public/tier1/xorstr.h b/r5dev/public/tier1/xorstr.h
new file mode 100644
index 00000000..852db63f
--- /dev/null
+++ b/r5dev/public/tier1/xorstr.h
@@ -0,0 +1,104 @@
+#pragma once
+#include <string>
+#include <array>
+#include <cstdarg>
+
+// https://stackoverflow.com/a/34981037
+
+#define BEGIN_NAMESPACE( x ) namespace x {
+#define END_NAMESPACE }
+
+BEGIN_NAMESPACE(XorCompileTime)
+
+constexpr auto time = __TIME__;
+constexpr auto seed = static_cast<int>(time[7]) + static_cast<int>(time[6]) * 10 + static_cast<int>(time[4]) * 60 + static_cast<int>(time[3]) * 600 + static_cast<int>(time[1]) * 3600 + static_cast<int>(time[0]) * 36000;
+
+// 1988, Stephen Park and Keith Miller
+// "Random Number Generators: Good Ones Are Hard To Find", considered as "minimal standard"
+// Park-Miller 31 bit pseudo-random number generator, implemented with G. Carta's optimisation:
+// with 32-bit math and without division
+
+template < int N >
+struct CRandomGenerator
+{
+private:
+    static constexpr unsigned a = 16807; // 7^5
+    static constexpr unsigned m = 2147483647; // 2^31 - 1
+
+    static constexpr unsigned s = CRandomGenerator< N - 1 >::value;
+    static constexpr unsigned lo = a * (s & 0xFFFF); // Multiply lower 16 bits by 16807
+    static constexpr unsigned hi = a * (s >> 16); // Multiply higher 16 bits by 16807
+    static constexpr unsigned lo2 = lo + ((hi & 0x7FFF) << 16); // Combine lower 15 bits of hi with lo's upper bits
+    static constexpr unsigned hi2 = hi >> 15; // Discard lower 15 bits of hi
+    static constexpr unsigned lo3 = lo2 + hi;
+
+public:
+    static constexpr unsigned max = m;
+    static constexpr unsigned value = lo3 > m ? lo3 - m : lo3;
+};
+
+template <>
+struct CRandomGenerator< 0 >
+{
+    static constexpr unsigned value = seed;
+};
+
+template < int N, int M >
+struct CRandomInt
+{
+    static constexpr auto value = CRandomGenerator< N + 1 >::value % M;
+};
+
+template < int N >
+struct CRandomChar
+{
+    static const char value = static_cast<char>(1 + CRandomInt< N, 0x7F - 1 >::value);
+};
+
+template < size_t N, int K, typename Char >
+struct CXorString
+{
+private:
+    const char _key;
+    std::array< Char, N + 1 > _encrypted;
+
+    constexpr Char Encrypt(Char c) const
+    {
+        return c ^ _key;
+    }
+
+    Char Decrypt(Char c) const
+    {
+        return c ^ _key;
+    }
+
+public:
+    template < size_t... Is >
+    constexpr __forceinline CXorString(const Char* str, std::index_sequence< Is... >) : _key(CRandomChar< K >::value), _encrypted{ Encrypt(str[Is])... }
+    {
+    }
+
+    __forceinline decltype(auto) Decrypt(void)
+    {
+        for (size_t i = 0; i < N; ++i) {
+            _encrypted[i] = Decrypt(_encrypted[i]);
+        }
+        _encrypted[N] = '\0';
+        return _encrypted.data();
+    }
+};
+
+//--------------------------------------------------------------------------------
+//-- Note: XorStr will __NOT__ work directly with functions like printf.
+//         To work with them you need a wrapper function that takes a const char*
+//         as parameter and passes it to printf and alike.
+//
+//         The Microsoft Compiler/Linker is not working correctly with variadic 
+//         templates!
+//--------------------------------------------------------------------------------
+
+//Wrapper functions to work in all functions below
+#define XorStr( s ) []{ constexpr XorCompileTime::CXorString< sizeof(s)/sizeof(char) - 1, __COUNTER__, char > expr( s, std::make_index_sequence< sizeof(s)/sizeof(char) - 1>() ); return expr; }().Decrypt()
+#define XorStrW( s ) []{ constexpr XorCompileTime::CXorString< sizeof(s)/sizeof(wchar_t) - 1, __COUNTER__, wchar_t > expr( s, std::make_index_sequence< sizeof(s)/sizeof(wchar_t) - 1>() ); return expr; }().Decrypt()
+
+END_NAMESPACE
\ No newline at end of file