Ears to the rescue

Pragyan CTF 2018 - Forensic (150 pts).

Pragyan CTF 2018: Ears to the rescue

Challenge details

Event Challenge Category Points Solves
Pragyan CTF 2018 Ears to the rescue Forensic 150 52

Download: audible.wav


Jack is trapped inside a room. All he can see and hear is a sound, his ears hear only the specific sound.

He needs to escape, help him figure out what the sound means.


Reading the description of the challenge, we are advised that by listening to the soundtrack, we would be likely to help Jack to escape from a room.

As this is an audio stream, let’s use our must-have audio processing tool: Audacity.


From this interesting output, we can quickly identify eight levels of quantization, as follows:

3-bit quantization

Let’s try to implement this quantization process using Python: decode.py

# python decode.py
The flag is :- pctf{SuRf1n6_th3~4udI0_w4v3s.f0r^lif3}

Here we got the flag!

Final flag: