We want to play a game with you. The mission is simple: you need to guess our flag, thatβs all. We use an algorithm to determine the similarity of strings.
Solution
The server accepts a guess, and calculates the Levenshtein distance between our guess and the flag.
We can think of the Levinshtien distance as the minimum number of single-character
Insertions,
Deletions, or
Substitutions
required to change our guess to the flag.
We can simply start off with the guess spbctf{<28 spaces>}. Since we know the space character will never be part of the flag, the Levenshtien distance simplifies to the number of wrong characters in our guess.