Paper Plane

The description is mentioning something about Infinite Garble Extension, which is used in Telegram (searching the name of the Python class, aesige), hence the name “Paper Plane” - Telegram’s logo. The only observation needed to solve this challenge is that, decryption on a single block can be done without including the entire ciphertext. We only need the first block of ciphertext, and the m0 and c0 corresponding to that block. The very first block will have m0 and c0 provided, and consequent blocks will use the previous plaintext block decrypted for m0, and its corresponding ciphertext block for c0....