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BroncoCTF Puzzle Solved Using Periodic Table as a Coordinate Cipher

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A BroncoCTF challenge presented participants with a file containing comma-separated integer tuples and literal characters, offering no decoding instructions. Solvers determined that each tuple represented periodic table coordinates — a period and group number — mapping to element symbols such as Bromine (Br), Oxygen (O), Nitrogen (N), and Cobalt (Co), which together spelled the flag prefix 'Bronco'. Three-element tuples added a letter-index layer, allowing individual characters to be extracted from two-letter element symbols. Two anomalous tuples could not be resolved through the table directly, but surrounding context made the intended letters clear. The final decoded flag was bronco{MY_FAVORITE_MESSAGES_HAVE_AN_ELEMENT_OF_SURPRISE}, consistent with the cipher's chemistry theme.

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