Challenge Overview
What can you do with this file?
I forgot the key to my safe but this file is supposed to help me with retrieving the lost key. Can you help me unlock my safe?
Solution
wget https://artifacts.picoctf.net/c/290/SafeOpener.class
cat SafeOpener.class
The flag near the end of the file.
Alternatively if you want to do the challenge the way it was probably intended (decompling the file) you can use jd-gui.
sudo apt install jd-gui
I then opened the file.
Than saved the file.
Once it was saved I ran this command to get only the flag.
cat SafeOpener.java | grep pico | cut -d "\"" -f1
Grep gets the line with "pico" which is the flag. And cut looks at the " delimiter where I used \ as an escape charater, -f1 is for looking at the first feild.
Flag: picoCTF{SAf3_0p3...8a993}