morse-code | picoCTF 2022 Solutions

Description

A short WAV file encodes the flag in Morse. Decode the audio, replace spaces with underscores, and wrap it in picoCTF{...}.

Setup

Upload the WAV to an online Morse decoder (e.g., morsecode.world → Audio Decoder) or decode manually.

The plaintext reads `WH47 H47H 90D W20U9H7`. Convert spaces to underscores and lowercase per the prompt.

echo "WH47 H47H 90D W20U9H7" | tr ' ' '_' | tr '[:upper:]' '[:lower:]' | sed 's/^/picoCTF{/' | sed 's/$/}/'

Step 1Run the audio through a decoder
The file is only ~30 seconds long; most online Morse decoders output the letters immediately.
Step 2Apply the required formatting
The challenge asks for lowercase with underscores. Use tr/sed to format the decoded phrase into picoCTF{...}.

picoCTF{wh47_h47h_90d_w20u9h7}

Simple signal-processing exercise, so there's no need for heavy tooling.