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ISSessions CTF 2021 Programming - Base64

Mar 31, 2021 | 1 minute read

Base64

Similar to the other challenges, take an input, base64 it, and then return it within 3 seconds.

Solution

The code breakdown is the same as the other bash solutions, but the key note is base64 -w0 to put the output all on one line instead of splitting it to fit in smaller terminals.

#!/bin/bash
data=$(curl -c base64cookies "http://progbase64.ctf.issessions.ca/" | grep -oE "data\".*" | grep -oE "[a-f0-9]{10}+" | tr -d '\n' | base64 -w0)
b64=$(echo $data | base64 -w0 )
echo $b64
curl -b base64cookies "http://progbase64.ctf.issessions.ca/index.php?answer=$data"