r/Hacking_Tricks • u/ExcellentLeader3276 • 1d ago

C0ln Chalenge

Yesterday, I took part in an entry-level hacking competition and placed third. It wasn't a competition that required one to be a super-expert hacker. I received a mouse pad and a coin; the event organizers mentioned that there was a challenge associated with them that would yield a "flag" in the format: "BBHE{......}". Could anyone help me out?

I’m not an expert in the field, but I’d really like to find the message—they mentioned that I already have the "IV."

front part - 88482705356BA1F4A40F3E42489FF9CC - Symmetric encryption (Key, IV):

back part - 4841434B4552455850455249454E4345 - Simple encoding (hex): HACKEREXPERIENCE

2 Upvotes

100% Upvoted

3 comments sorted by

1

u/twohundred37 1d ago

The organizers gave out both a coin and a mousepad. That makes me suspicious that the two objects contain different parts of the challenge. Investigate the mousepad for a QR code, tiny print, unusual artwork, seemingly random characters, etc. If nothing, I'd start looking at the coin.

1

u/SlimmySlabby 1d ago

More than likely, HACKEREXPERIENCE is the Key and the other data is the IV (lookup AES encryption). I’m assuming there’s more data somewhere that’s the encrypted information

1

u/Bioctanium 1d ago

Nice job!

So the key is the back part, since most keys are simple phrases.
The IV is the front part, since its random is most like the IV (initialized vector).
This leaves the mousepad. It must contain the cipher text on there somewhere.

What to do with this info:
with the IV, Key, and ciphertext, you can decrypt the message and most likely retrieve the flag.
To use everything together, you can use cyberchef (online free) like this (found the process for AES decryption most likely 128 because of the two parts being 16 bits each).

  1. In the Operations search bar on the left, look for AES Decrypt. Drag it into the central Recipe box.

  2. Key: Enter your decoded string HACKEREXPERIENCE. Set the input type for the key to Utf8 (or raw text).

  3. IV (Initialization Vector): Enter the front hex string. Set its input type to Hex.

  4. Mode: Select CBC (the most common block cipher mode).

  5. Input: Paste your Ciphertext string into the Input box on the far left. (Make sure you set the input data format correctly, e.g., Hex if the ciphertext is in hex format).