def detect_ecb(oracle, keysize):
"""Detect ECB encryption."""
c = chunks(oracle(b"A" * 100), keysize)
if count_repeats(c) > 0:
return True
else:
return False
def decrypt(self, ciphertext):
"""Decrypt ciphertext with key using AES-128-CBC."""
c = chunks(ciphertext, self.keysize)
plaintext = xor(super().decrypt(c[0]), self.iv)
for i in range(0, len(c) - 1):
plaintext += xor(c[i], super().decrypt(c[i + 1]))
return plaintext
def encrypt(self, plaintext):
"""Encrypt ciphertext with key using AES-128-CBC."""
p = chunks(plaintext, self.keysize)
c = super().encrypt(xor(p[0], self.iv))
ciphertext = c
for chunk in p[1:]:
c1 = super().encrypt(xor(c, chunk))
ciphertext += c1
c = c1
return ciphertext
def decrypt(self, ciphertext):
"""Decrypt ciphertext with key using AES-128-CTR."""
counter = 0
plaintext = b""
c = chunks(ciphertext, 16)
for chunk in c:
n = len(chunk)
keystream = ECB(self.key).encrypt(self.nonce + pack("Q", counter))
plaintext += xor(keystream[0:n], chunk)
counter += 1
return plaintext
def __init__(self, ciphertexts):
"""List of ciphertexts."""
self.ciphertexts = ciphertexts
self.keysize = 16
self.scores = []
cnt = 1
for ciphertext in self.ciphertexts:
c = chunks(line, self.keysize)
self.scores.append((cnt, count_repeats(c)))
cnt += 1
# most likely ciphertext encrypted with AES-128-ECB
self.ciphertext = max(self.scores, key=lambda x: x[1])[0]