Players modifying save files is a common concern, particularly with human-readable formats like JSON. Here are several approaches to protect your save data:
Checksum Validation
Add a checksum to your save data to detect modifications:
#include <cstdint>
#include <string>
uint32_t CalculateChecksum(
const std::string& Data) {
uint32_t Checksum{0};
for (char c : Data) {
// Simple hash function
Checksum = (Checksum + c) * 17;
}
return Checksum;
}
void SaveGame(const GameState& State) {
std::string JsonData = SerializeToJson(State);
uint32_t Checksum = CalculateChecksum(
JsonData);
SaveFile File;
File.Data = JsonData;
File.Checksum = Checksum;
WriteToFile("save.json", File);
}
bool LoadGame(GameState& State) {
SaveFile File = ReadFromFile("save.json");
if (CalculateChecksum(File.Data) != File.
Checksum) {
return false; // Save file was modified
}
State = DeserializeFromJson(File.Data);
return true;
}Encryption
For stronger protection, encrypt the save data:
#include <string>
#include <vector>
std::vector<char> EncryptData(
const std::string& Data,
const std::string& Key
) {
std::vector<char> Encrypted;
for (size_t i = 0;
i < Data.length(); ++i) {
Encrypted.push_back(
Data[i] ^ Key[i % Key.length()]);
}
return Encrypted;
}
void SaveGame(const GameState& State) {
std::string JsonData = SerializeToJson(State);
auto Encrypted = EncryptData(
JsonData, "SecretKey123");
WriteToFile("save.dat", Encrypted);
}Binary Format
Consider using binary format instead of JSON - it's harder to modify and more efficient:
void SaveBinary(const GameState& State) {
std::ofstream File{
"save.dat", std::ios::binary};
File.write(
reinterpret_cast<const char*>(&State),
sizeof(GameState)
);
}Remember that determined players can still modify binary saves or break encryption. The goal is to prevent casual tampering while keeping save files efficient and reliable for honest players.
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This Question is from the Lesson:
Working with Data
Learn techniques for managing game data, including save systems, configuration, and networked multiplayer.
