Challenge Description
What is ROT13?
ROT13 (“rotate by 13 places”) is a simple letter substitution cipher that replaces each letter with the letter 13 positions after it in the alphabet. Since the English alphabet has 26 letters, applying ROT13 twice returns the original text. The cipher is its own inverse.
The name of this challenge, 13, directly references this rotation value.
| A | B | C | D | E | F | G | H | I | J | K | L | M | | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
So
AbecomesN,BbecomesO, and so on. Non-alphabetic characters (digits, punctuation, spaces) are left unchanged.
As the description suggests, we only have to copy the string of characters provided and decrypt using ROT13. I used CyberChef to do this, and obtained the flag.
Flag
picoCTF{not_too_bad_of_a_problem}