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picoCTF 2021 -The Numbers writeup-

Shitian Daxiang
Bio := struct {Identity, Undergrad, Research}{ "Ainu descendants", "📊 Data Science", "🔬 Privacy Preserving Data Mining"}
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The numbers... what do they mean?


When the image is opened, the following image is displayed.

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Since { appears in the seventh character of the image, we can a find out that the flag format is picoctf{***}. This means that 16→P, 9→I, 3→C, 15→O, 3→C, 20→T, and 6→F are used.
And from this rule, we can assume that Letter Number Cypher (A1Z26), which converts numbers directly into alphabets, is used.

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All you need to do is decode A1Z26 with Cyberchef or convert it manually to get the flag.
But don't forget to add {} and type the flag in uppercase.


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