202 lines
7.7 KiB
C++
202 lines
7.7 KiB
C++
#pragma once
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#include <cstdio>
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#include <cstring>
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#include <array>
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#include <string_view>
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namespace str_obf {
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constexpr static auto max_key_power = 6; /* 64 bytes max */
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namespace internal {
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template <typename char_t, std::uint64_t buffer_size, std::uint64_t size, typename key_t>
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struct message {
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/* helper to access the types */
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static constexpr auto _size = size;
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using _char_t = char_t;
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using _key_t = key_t;
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/* memory */
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std::array<char_t, buffer_size> buffer{};
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key_t key{};
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/* some memory access helpers */
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[[nodiscard]] std::string_view string_view() const noexcept { return {this->buffer.begin(), this->length}; }
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[[nodiscard]] std::string string() const { return {this->buffer.begin(), this->length}; }
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[[nodiscard]] const char* c_str() const noexcept { return &this->buffer[0]; }
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};
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constexpr auto time_seed() noexcept {
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std::uint64_t shifted = 0;
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for(const auto c : __TIME__)
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{
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shifted <<= 8U;
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shifted |= (unsigned) c;
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}
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return shifted;
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}
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constexpr uint64_t string_hash(const char* str, int h = 0) noexcept {
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return !str[h] ? 5381 : (unsigned) (string_hash(str, h + 1) * 33) ^ (unsigned) str[h];
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}
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#ifdef WIN32
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#pragma warning(disable: 4146) // unary minus operator applied to unsigned type, result still unsigned
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#endif
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constexpr std::uint32_t rng32_next(std::uint64_t& state, const std::uint32_t& inc) noexcept {
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std::uint64_t oldstate = state;
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// Advance internal state
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state = oldstate * 6364136223846793005ULL + (inc | 1UL);
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// Calculate output function (XSH RR), uses old state for max ILP
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std::uint32_t xorshifted = (uint32_t) (((oldstate >> 18u) ^ oldstate) >> 27u);
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std::uint32_t rot = oldstate >> 59u;
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return (xorshifted >> rot) | (xorshifted << ((-rot) & 31));
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}
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#ifdef WIN32
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#pragma warning(default: 4146) // unary minus operator applied to unsigned type, result still unsigned
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#endif
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/* we use a buffer dividable by 8 so the compiler could do crazy shit, when loading (moving) the characters */
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constexpr std::uint64_t recommand_message_buffer(std::uint64_t message_size) noexcept {
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if(message_size <= 4) return 4; /* we could use the eax register here */
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return (message_size & 0xFFFFFFF8) + ((message_size & 0x7) > 0 ? 8 : 0);
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}
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}
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inline void _invalid_key_size() {}
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template <typename char_t, typename key_t>
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constexpr inline void crypt(char_t* begin, std::uint64_t length, const key_t& key) noexcept {
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static_assert(sizeof(char_t) == 1, "Currently only 8 bit supported");
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if(length == 0) return;
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if(key.size() == 0) _invalid_key_size();
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if(key.size() & (key.size() - 1UL)) _invalid_key_size(); /* key must be an power of 2 */
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auto left = length;
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size_t key_index{0};
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while(left-- > 0) {
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key_index &= key.size();
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*begin ^= key[key_index + key_index];
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}
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}
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template <typename char_t, std::uint64_t message_size, typename key_t>
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constexpr inline auto encode(const char_t(&message)[message_size], const key_t& key) noexcept {
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constexpr auto message_buffer_size = internal::recommand_message_buffer(message_size);
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internal::message<char_t, message_buffer_size, message_size, key_t> result{};
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result.key = key;
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{
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auto bit = result.buffer.begin();
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auto mit = message;
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std::uint64_t index = message_size;
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while(index-- > 0)
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*bit++ = *mit++;
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std::uint64_t padding = message_buffer_size - message_size;
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if(padding) { /* to make the string end less obvious we add some noise here (it does not harm user performance) */
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std::uint64_t rng_seed = internal::time_seed() ^ internal::string_hash(message, 0);
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std::uint64_t rng_base = rng_seed;
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while(padding-- > 0)
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*bit++ = internal::rng32_next(rng_base, (uint32_t) rng_seed) & 0xFFUL;
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}
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}
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crypt<char_t, key_t>(result.buffer.data(), message_size, key);
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return result;
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}
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template <typename char_t, std::uint64_t length>
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constexpr inline auto str_length(const char_t(&message)[length]) noexcept { return length; }
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template <typename char_t, std::uint64_t buffer_size, std::uint64_t message_size, typename key_t>
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inline std::string decode(const internal::message<char_t, buffer_size, message_size, key_t>& message) {
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std::string result{};
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result.resize(message_size);
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memcpy(result.data(), message.buffer.begin(), message_size);
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crypt(result.data(), message_size, message.key);
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return result;
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}
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/* length is a power of 2! */
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constexpr inline std::uint64_t generate_key_length(std::uint64_t seed, std::uint64_t message_size) noexcept {
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if(message_size <= 1) return 1;
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size_t power2{0};
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while(message_size >>= 1U)
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power2++;
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if(power2 > max_key_power)
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power2 = max_key_power;
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std::uint64_t rng_base = seed;
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std::uint64_t length = 0;
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do {
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length = (std::uint64_t) ((internal::rng32_next(rng_base, (uint32_t) seed) >> 12UL) & 0xFFUL);
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} while(length == 0 || length > power2);
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return uint64_t{1} << length;
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}
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template <uint64_t line_number, std::uint64_t message_size>
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constexpr inline auto generate_key(const char* _str_seed) noexcept {
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std::uint64_t rng_seed = internal::time_seed() ^ internal::string_hash(_str_seed, 0) ^ line_number;
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std::uint64_t rng_base = rng_seed;
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constexpr std::uint64_t key_length = generate_key_length(internal::time_seed() ^ (line_number << 37UL), message_size);
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std::array<uint8_t, key_length> result{};
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for(auto& it : result)
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it = (internal::rng32_next(rng_base, (uint32_t) rng_seed) >> 16UL) & 0xFFUL;
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return result;
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}
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template <typename message>
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struct decode_helper {
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const message& encoded;
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std::array<typename message::_char_t, message::_size> buffer{0};
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bool decoded = false; /* a trivial check which (if this only gets used once) the compiler could evaluate */
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#ifndef _MSC_VER /* else if you call string_view() or string() it wound inline this method */
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__attribute__((always_inline)) inline
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#else
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__forceinline
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#endif
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const char* c_str() noexcept {
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if(!this->decoded) {
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memcpy(this->buffer.data(), this->encoded.buffer.data(), message::_size);
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crypt<
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typename message::_char_t,
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typename message::_key_t
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>((typename message::_char_t*) &this->buffer[0], message::_size, this->encoded.key);
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this->decoded = true;
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}
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return &this->buffer[0];
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}
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inline std::string_view string_view() noexcept {
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return {this->c_str(), message::_size - 1};
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}
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inline std::string string() { return {this->c_str(), message::_size - 1}; }
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//operator const char*() noexcept { return this->c_str(); }
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};
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}
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#define strobf_define(variable_name, string) \
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constexpr auto variable_name = ::str_obf::encode(string, str_obf::generate_key<__LINE__, str_obf::str_length(string)>(__FILE__ __TIME__))
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#define strobf_val(variable_name) (str_obf::decode_helper<decltype(variable_name)>{variable_name})
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#define strobf(message) \
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(([]{ \
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static strobf_define(_, message); \
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return strobf_val(_); \
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})())
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