Description
A mysterious file named enc_flag hides nested encodings. Your task is to unwrap each layer until the plain-text flag appears.
Setup
Fetch the provided enc_flag file and work from a shell where you can chain decoding utilities.
Prepare a helper script or rely on CyberChef to repeatedly decode from Base64 until human-readable text appears.
wget https://artifacts.picoctf.net/c/451/enc_flag && \
printf "cat enc_flag | base64 --decode | base64 --decode | base64 --decode | base64 --decode | base64 --decode | base64 --decode\n" > decode.sh && \
chmod +x decode.sh
Solution
- Step 1Automate the decodingExecute the helper script to stream the file through six Base64 decoders. The output collapses to the original ASCII message../decode.sh
- Step 2Alternative: CyberChefIf you prefer a GUI, paste the file contents into CyberChef and chain multiple From Base64 operations until the flag is shown.
Flag
picoCTF{base64_n3st...e523f49}
Each Base64 decode peels a layer; six iterations reveal the final picoCTF flag.