Obfuscate Data

Another technique to protect memory from being modified is to obfuscate data. Obfuscating or encrypting key data is possible through various means. Before writing to memory, either obfuscate a variable or encrypt it. There are various techniques for achieving this, ranging from a simple XOR to more complex encryption methods. If you are combining this with a duplication technique you could even hash the duplicate and incorporate the hash check into the verify logic.

Obfuscating your data will ensure that it is harder for a cheater to find key variables in memory.

Example Code

iOS/Objective-C

Android/Java

Unity/C#

// Make sure to xor the initial score
- (id)init {
    self = [super init];
    if (self) {
        xorCode_ = 12345; // USE A DIFFERENT XOR VALUE THAN THIS!
        score_ = score_ ^ xorCode_;
    }
}

// Functions and mutators should xor the value before using it, and xor
// the value again before the function exits
- (void) addScore: (int) increase {
    score_ = score_ ^ xorCode_;
    score_ += increase;
    score_ = score_ ^ xorCode_;
}

// Accessors just need to return the xor'd value
- (int) getScore {
    return score_ ^ xorCode_;
}

private int xorCode = 12345; // USE A DIFFERENT XOR VALUE THAN THIS!
private int score = 0;

// Make sure to xor the initial score
@Override
private void onCreate(Bundle savedInstanceState) {
    score = score ^ xorCode;
}

// Functions and mutators should xor the value before using it, and xor
// the value again before the function exits
private void addScore(int increase) {
    score ^= xorCode;
    score += increase;
    score ^= xorCode;
}

// Accessors just need to return the xor'd value
private int getScore () {
    return score ^ xorCode;
}

private int xorCode = 12345; // USE A DIFFERENT XOR VALUE THAN THIS!
private int score = 0;

// Make sure to xor the initial score
void Awake() {
    score = score ^ xorCode;
}

// Functions and mutators should xor the value before using it, and xor
// the value again before the function exits
private void AddScore(int increase) {
    score ^= xorCode;
    score += increase;
    score ^= xorCode;
}

// Accessors just need to return the xor'd value
private int GetScore () {
    return score ^ xorCode;
}