A developer reverse-engineered a challenge-code format in a country guessing game using GPT-6 Astra, discovering that the tokens contained country ISO codes (like 'kr' for South Korea, 'de' for Germany) obfuscated through XOR operations with random bytes, along with a SHA-256 checksum for validation. The analysis demonstrates that security through obfuscation alone is insufficient, as AI can deduce encoded patterns from multiple examples without access to source code.