CTF Writeup – The Numbers – PicoCTF

CTF Writeup by Frigyes

This challenge was originally on PicoCTF 2019.

Decription: The numbers… what do they mean?

We get an image with the challenge:

The curly braces are dead giveaway of the key. Considering the picoCTF key format of picoCTF{}, I can map the first 7 numbers to the string “PICOCTF”. From this I deduce that the numbers indicate the index of the letter in the English alphabet: 16 = P, 9 = I, 3 = C, etc.
Following this pattern will yield us the flag:

PICOCTF{THENUMBERSMASON}

If you want to exercise your CTF skills, PicoGym is an excellent site you can use

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