test_ecb.py

test_ecb.py

from Crypto.Cipher import AES
import string
import os

key = os.urandom(16)
# For brute-force
chars = string.ascii_uppercase + string.ascii_lowercase + string.digits
SECRET = b'IenagaMugiKawaii'

def pad(m):
    return m + b'\x00'*(16 - len(m) % 16)

def encrypt(message):
    aes = AES.new(key, AES.MODE_ECB)
    return aes.encrypt(pad(message))

def bytes_split(message):
    return [message[i:i+16] for i in range(0, len(message), 16)]

def show_blocks(message):
    for block in bytes_split(message):
        print(block)
    print()


if __name__ == '__main__':

    S = []
    for _ in range(len(SECRET)):
        for ch in chars:
            pt = b'a'*(15-len(S)) + b"".join(S) + ch.encode()
            pt += b'a'*(15-len(S))
            pt += SECRET
            ct = encrypt(pt)

            print(ch, end="\n")
            show_blocks(ct)

            blocks = bytes_split(ct)
            if len(blocks) != len(set(blocks)):
                print("OK", ch)
                S.append(ch.encode())
                break
    print(b"".join(S))