THE GARDEN

packet-story

Updated 20 Sep 2026

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  Attribution

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    Solved by Muhammad Dhafin Ramadhan during the competition. These are rn’s study notes based on the teammate’s documented solve, not an independent rn solve.

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  What it asked

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    Reassemble an HTTP chunked body, then apply the declared Base64 and Gzip layers.

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  Approach

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    Each chunk begins with a hexadecimal length. Read exactly that many bytes, concatenate them, and stop at the zero-length chunk.

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    The reconstructed body is Base64 text. Decoding it begins with Gzip magic bytes 1f 8b 08; decompression reveals the JSON flag.

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  Solution

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    import base64, gzip
    
    chunks = [
        "H4sIAJ9LmmoC/6tWKi", "5JLCktVrJSys9W0lHK", "yy9JBbJTUpPzcwuKUo",
        "uLFUCMnFSgqI5SWk5i", "OlDS29czwM+iugioJq", "+4pKg0uSQ+KTUtvyg1",
        "vjK/NB6kNSW1VqkWAK", "Zf/Y9bAAAA",
    ]
    print(gzip.decompress(base64.b64decode("".join(chunks))).decode())
    

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  Verification

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    The reconstructed body decompresses locally to the recorded flag.

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  Concepts

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    HTTP chunked transfer encoding; Base64; file signatures; Gzip decompression.

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  Source

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    Source: team document KMIPNVIII-unintended.docx, titled “Writeup unintended KMIPN 8 Final”. Page numbers refer to the rendered document. Rendered pp. 39–41.

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    Flag: KMIPN8{reconstruct_before_you_decode}.

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