Description
A substitution cipher with no punctuation must be solved to recover a block of prose ending in the flag. Online solvers can handle the bulk of the decoding, but you’ll need to map the remaining characters manually.
Setup
Load the ciphertext into a substitution solver such as quipqiup.com.
The solver recovers nearly the entire plaintext, but the final line (the flag) includes underscores and digits that may be mangled.
Manually align the decoded letters with the ciphertext to reconstruct the flag.
Solution
- Step 1Leverage an automatic solverTools like quipqiup produce a readable paragraph about offensive competitions. Copy the output and focus on the last sentence (the one mentioning the flag).
- Step 2Fix the flag charactersBecause underscores/numbers confused the solver, cross-reference the original ciphertext’s ending (`qcuhUIE{...}`) with the decoded letters to get picoCTF{N6R4M_4N41Y515_15_73D10U5_702F03FC}.
Flag
picoCTF{N6R4M_4N41Y515_15_73D10U5_702F03FC}
Classic substitution can be solved in seconds with automated tools, but always verify the final characters.