* The key point was to `recover the IV` which was used in AES .
* It can be easily noted that pad function adds `16 bytes of hex("16")` at the end of the plaintext.
* As EBC is used ,the 2 plaintext blocks will be encrypted to same ciphertext and therefore the returned `hex string[-16:]` is the `IV`.
* Now you have everything you need and you can decrypt the ciphertext blocks one by one :)

Original writeup (https://github.com/0m3g4-ops/DU_CTF/blob/master/extra_cool_blockchain.py).