C++: How to encrypt strings at compile time?
you can encrypt it using macros or write your own preprocessor
#define CRYPT8(str) { CRYPT8_(str "\0\0\0\0\0\0\0\0") }
#define CRYPT8_(str) (str)[0] + 1, (str)[1] + 2, (str)[2] + 3, (str)[3] + 4, (str)[4] + 5, (str)[5] + 6, (str)[6] + 7, (str)[7] + 8, '\0'
// calling it
const char str[] = CRYPT8("ntdll");I also thought this wasn't possible, even though it's very simple, people wrote solutions where you need a custom tool to scan the built file afterwards and scan for strings and encrypt the strings like that, which wasn't bad but I wanted a package that's compiled from Visual Studio, and it's possible now!
What you need is C++ 11 (Visual Studio 2015 Update 1 out of the box)
the magic happens with this new command constexpr
By magic happens in this #define
#define XorString( String ) ( CXorString<ConstructIndexList<sizeof( String ) - 1>::Result>( String ).decrypt() )
It won't decrypt the XorString at compile-time, only at run-time, but it will encrypt the string only in compile-time, so the strings will not appear in the Executable file
printf(XorString( "this string is hidden!" ));
It will print out "this string is hidden!" but you won't find it inside Executable file as strings!, check it yourself with Microsoft Sysinternals Strings program download link: https://technet.microsoft.com/en-us/sysinternals/strings.aspx
The full source code is quite large but could easily be included into one header file. But also quite random so the encrypted string outputs will always change every new compile, the seed is changed based on the time it took it compile, pretty much solid,perfect solution.
Create a file called XorString.h
#pragma once
//-------------------------------------------------------------//
// "Malware related compile-time hacks with C++11" by LeFF //
// You can use this code however you like, I just don't really //
// give a shit, but if you feel some respect for me, please //
// don't cut off this comment when copy-pasting... ;-) //
//-------------------------------------------------------------//
////////////////////////////////////////////////////////////////////
template <int X> struct EnsureCompileTime {
enum : int {
Value = X
};
};
////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////
//Use Compile-Time as seed
#define Seed ((__TIME__[7] - '0') * 1 + (__TIME__[6] - '0') * 10 + \
(__TIME__[4] - '0') * 60 + (__TIME__[3] - '0') * 600 + \
(__TIME__[1] - '0') * 3600 + (__TIME__[0] - '0') * 36000)
////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////
constexpr int LinearCongruentGenerator(int Rounds) {
return 1013904223 + 1664525 * ((Rounds> 0) ? LinearCongruentGenerator(Rounds - 1) : Seed & 0xFFFFFFFF);
}
#define Random() EnsureCompileTime<LinearCongruentGenerator(10)>::Value //10 Rounds
#define RandomNumber(Min, Max) (Min + (Random() % (Max - Min + 1)))
////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////
template <int... Pack> struct IndexList {};
////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////
template <typename IndexList, int Right> struct Append;
template <int... Left, int Right> struct Append<IndexList<Left...>, Right> {
typedef IndexList<Left..., Right> Result;
};
////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////
template <int N> struct ConstructIndexList {
typedef typename Append<typename ConstructIndexList<N - 1>::Result, N - 1>::Result Result;
};
template <> struct ConstructIndexList<0> {
typedef IndexList<> Result;
};
////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////
const char XORKEY = static_cast<char>(RandomNumber(0, 0xFF));
constexpr char EncryptCharacter(const char Character, int Index) {
return Character ^ (XORKEY + Index);
}
template <typename IndexList> class CXorString;
template <int... Index> class CXorString<IndexList<Index...> > {
private:
char Value[sizeof...(Index) + 1];
public:
constexpr CXorString(const char* const String)
: Value{ EncryptCharacter(String[Index], Index)... } {}
char* decrypt() {
for(int t = 0; t < sizeof...(Index); t++) {
Value[t] = Value[t] ^ (XORKEY + t);
}
Value[sizeof...(Index)] = '\0';
return Value;
}
char* get() {
return Value;
}
};
#define XorS(X, String) CXorString<ConstructIndexList<sizeof(String)-1>::Result> X(String)
#define XorString( String ) ( CXorString<ConstructIndexList<sizeof( String ) - 1>::Result>( String ).decrypt() )
////////////////////////////////////////////////////////////////////
THIS IS A UPDATED CODE BELOW, WORKS on both char and wchar_t thanks to arkan
#pragma once
#include <string>
#include <array>
#include <cstdarg>
#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 RandomGenerator
{
private:
static constexpr unsigned a = 16807; // 7^5
static constexpr unsigned m = 2147483647; // 2^31 - 1
static constexpr unsigned s = RandomGenerator< 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 RandomGenerator< 0 >
{
static constexpr unsigned value = seed;
};
template < int N, int M >
struct RandomInt
{
static constexpr auto value = RandomGenerator< N + 1 >::value % M;
};
template < int N >
struct RandomChar
{
static const char value = static_cast< char >(1 + RandomInt< N, 0x7F - 1 >::value);
};
template < size_t N, int K, typename Char >
struct XorString
{
private:
const char _key;
std::array< Char, N + 1 > _encrypted;
constexpr Char enc(Char c) const
{
return c ^ _key;
}
Char dec(Char c) const
{
return c ^ _key;
}
public:
template < size_t... Is >
constexpr __forceinline XorString(const Char* str, std::index_sequence< Is... >) : _key(RandomChar< K >::value), _encrypted{ enc(str[Is])... }
{
}
__forceinline decltype(auto) decrypt(void)
{
for (size_t i = 0; i < N; ++i) {
_encrypted[i] = dec(_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!
//
// Use the functions below or use std::cout (and similar)!
//--------------------------------------------------------------------------------
static auto w_printf = [](const char* fmt, ...) {
va_list args;
va_start(args, fmt);
vprintf_s(fmt, args);
va_end(args);
};
static auto w_printf_s = [](const char* fmt, ...) {
va_list args;
va_start(args, fmt);
vprintf_s(fmt, args);
va_end(args);
};
static auto w_sprintf = [](char* buf, const char* fmt, ...) {
va_list args;
va_start(args, fmt);
vsprintf(buf, fmt, args);
va_end(args);
};
static auto w_sprintf_ret = [](char* buf, const char* fmt, ...) {
int ret;
va_list args;
va_start(args, fmt);
ret = vsprintf(buf, fmt, args);
va_end(args);
return ret;
};
static auto w_sprintf_s = [](char* buf, size_t buf_size, const char* fmt, ...) {
va_list args;
va_start(args, fmt);
vsprintf_s(buf, buf_size, fmt, args);
va_end(args);
};
static auto w_sprintf_s_ret = [](char* buf, size_t buf_size, const char* fmt, ...) {
int ret;
va_list args;
va_start(args, fmt);
ret = vsprintf_s(buf, buf_size, fmt, args);
va_end(args);
return ret;
};
//Old functions before I found out about wrapper functions.
//#define XorStr( s ) ( XorCompileTime::XorString< sizeof(s)/sizeof(char) - 1, __COUNTER__, char >( s, std::make_index_sequence< sizeof(s)/sizeof(char) - 1>() ).decrypt() )
//#define XorStrW( s ) ( XorCompileTime::XorString< sizeof(s)/sizeof(wchar_t) - 1, __COUNTER__, wchar_t >( s, std::make_index_sequence< sizeof(s)/sizeof(wchar_t) - 1>() ).decrypt() )
//Wrapper functions to work in all functions below
#define XorStr( s ) []{ constexpr XorCompileTime::XorString< 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::XorString< 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
Building on SSPoke's answer here is a slightly simpler and more robust solution. Tested with MSVC 2017 and gcc 7.3 https://godbolt.org/z/7fc3Zi
Changes:
- Fix integer overflow warning for long strings
- Fix/Make sure MSVC evaluate encrypt_character() at compile time even for very long strings (in the original version some strings would not get encrypted at compile time)
- Support for wide character strings
- Simpler code templates
#include <iostream>
// =============================================================================
namespace crypt {
// =============================================================================
// convert __TIME__ == "hh:mm:ss" to a sum of seconds this gives us a compile-time seed
// Note: in some weird cases I've seen the seed being different from encryption
// to decryption so it's safer to not use time and set the seed manually
#if 0
#define TBX_XSTR_SEED ((__TIME__[7] - '0') * 1ull + (__TIME__[6] - '0') * 10ull + \
(__TIME__[4] - '0') * 60ull + (__TIME__[3] - '0') * 600ull + \
(__TIME__[1] - '0') * 3600ull + (__TIME__[0] - '0') * 36000ull)
#else
#define TBX_XSTR_SEED (3600ull)
#endif
// -----------------------------------------------------------------------------
// @return a pseudo random number clamped at 0xFFFFFFFF
constexpr unsigned long long linear_congruent_generator(unsigned rounds) {
return 1013904223ull + (1664525ull * ((rounds> 0) ? linear_congruent_generator(rounds - 1) : (TBX_XSTR_SEED) )) % 0xFFFFFFFF;
}
// -----------------------------------------------------------------------------
#define Random() linear_congruent_generator(10)
#define XSTR_RANDOM_NUMBER(Min, Max) (Min + (Random() % (Max - Min + 1)))
// -----------------------------------------------------------------------------
constexpr const unsigned long long XORKEY = XSTR_RANDOM_NUMBER(0, 0xFF);
// -----------------------------------------------------------------------------
template<typename Char >
constexpr Char encrypt_character(const Char character, int index) {
return character ^ (static_cast<Char>(XORKEY) + index);
}
// -----------------------------------------------------------------------------
template <unsigned size, typename Char>
class Xor_string {
public:
const unsigned _nb_chars = (size - 1);
Char _string[size];
// if every goes alright this constructor should be executed at compile time
inline constexpr Xor_string(const Char* string)
: _string{}
{
for(unsigned i = 0u; i < size; ++i)
_string[i] = encrypt_character<Char>(string[i], i);
}
// This is executed at runtime.
// HACK: although decrypt() is const we modify '_string' in place
const Char* decrypt() const
{
Char* string = const_cast<Char*>(_string);
for(unsigned t = 0; t < _nb_chars; t++) {
string[t] = string[t] ^ (static_cast<Char>(XORKEY) + t);
}
string[_nb_chars] = '\0';
return string;
}
};
}// END crypt NAMESPACE ========================================================
#define XorS(name, my_string) constexpr crypt::Xor_string<(sizeof(my_string)/sizeof(char)), char> name(my_string)
// Because of a limitation/bug in msvc 2017 we need to declare crypt::Xor_string() as a constexpr
// otherwise the constructor is not evaluated at compile time. The lambda function is here to allow this declaration inside the macro
// because there is no such thing as casting to 'constexpr' (and casting to const does not solve this bug).
#define XorString(my_string) []{ constexpr crypt::Xor_string<(sizeof(my_string)/sizeof(char)), char> expr(my_string); return expr; }().decrypt()
// Crypt normal string char*
#define _c( string ) XorString( string )
#define XorWS(name, my_string) constexpr crypt::Xor_string<(sizeof(my_string)/sizeof(wchar_t)), wchar_t> name(my_string)
#define XorWideString(my_string) []{ constexpr crypt::Xor_string<(sizeof(my_string)/sizeof(wchar_t)), wchar_t> expr(my_string); return expr; }().decrypt()
// crypt wide characters
#define _cw( string ) XorWideString( string )
int main(void ) {
std::cout << _c("0obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze0\n"
"1obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze1\n"
"2obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze2\n"
"3obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze3\n"
"4obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze4\n"
"5obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze5\n"
"6obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze6\n"
"7obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze7\n"
"8obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze8\n"
"9obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze9\n" ) << std::endl;
std::cout << "Wide strings" << std::endl;
std::wcout << _cw(L"0obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze0\n"
"1obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze1\n"
"2obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze2\n"
"3obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze3\n"
"4obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze4\n"
"5obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze5\n"
"6obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze6\n"
"7obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze7\n"
"8obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze8\n"
"9obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzze obfuscate me pleazzzzzzeobfuscate me pleazzzzzze obfuscate me pleazzzzzze9\n") << std::endl;
return 0;
}