How Can We Effectively Prevent Highscore Cheating in Flash-Based PHP Games?

Mitigating Highscore Tampering in Flash-Based PHP Games

Introduction:
Maintaining the integrity of online game highscore tables is challenging due to the inherent vulnerabilities of Flash and PHP. This article explores the complexities of preventing score manipulation and provides effective strategies to mitigate this issue.

The Problem:
Flash code operates on the user's computer, making it susceptible to reverse engineering and manipulation. Users can alter variables and program behavior, leading to the potential for highscore forging.

Basic Solution Attempts:
Simple methods such as multiple score calls, checksums, and Fibonacci sequences have been employed but ultimately proved ineffective against determined attackers.

Advanced Solutions:
1. Token-Based Validation:
Bind each highscore save to a unique game instance by providing an encrypted token at game startup. The server verifies the token against the received score, preventing replay attacks.

2. Session Key and AES:
Generate a random 128-bit AES key encrypted with a key hardcoded into the Flash game. The highscore is then encrypted with the session key and the SHA1 hash of the score.

3. Server-Side Checks:
The PHP script checks the token for validity, decrypts the highscore, and verifies its SHA1 hash. If either check fails, the score is rejected.

Addressing Reverse Engineering and Memory Manipulation:

1. Countermeasures for Decompilation:
Obscure the AES code and scatter fake key encryptions to hinder understanding and tracing.

2. Server-Side Runtime Monitoring:
Track game durations, heartbeat scores, and game states. Filter out suspicious behavior, such as low-duration games or abnormal score growth.

3. Account Disabling:
Disable accounts associated with users who exhibit clear signs of tampering.

Conclusion:

Completely preventing highscore manipulation is impossible. However, by implementing multi-layered security measures and leveraging server-side monitoring, it is possible to deter and mitigate the issue. Remember to focus on making the attack more costly than using legitimate methods, ultimately protecting the integrity of your game.

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