# Plaid CTF 2016 - Morset

Points: 50
Category: Misc
Description
A mysterious signal… can you decode it? Running at morset.pwning.xxx:11821

After connecting to the service, you’ll receive some data that looks like morse code. If you enter some reply, you’ll receive more morse code that looks like a response. I also found out that if you send some morse code back, you’ll get a different response from if you send non-morse code characters, which seem to signify that the response is important for getting the flag.

Initially I couldn’t determine the encoding of the messages, not until bo787 mentioned that it could be base36 that I realize it is base36-encoded.

# Solution

Connecting to morset.pwning.xxx:11821 gives us:

I then use a simple python script to encode/decode the morse code, to give:

This is encoded with base36 encoding, we can decode with python easily by using int(a,36) on it and then decoding with hex.

So we can see that the response we need to provide is the answer to SHA256(Acorn3548096305).

I wrote a python script to automate the entire process + encode the answer back to base36 + morse code before replying the service and getting the flag.

Running the script gives us the flag:

And yay! we got the flag: PCTF{c0c0c0nutBaze_4__d4ys}.

Unfortunately I was busy with school and did not manage to play much or to solve other challenges.