def encrypt_user_data_cbc(user_data):
user_data = user_data.replace(";", "")
user_data = user_data.replace("=", "")
plaintext = "comment1=cooking%20MCs;userdata=" + user_data + ";comment2=%20like%20a%20pound%20of%20bacon"
to_encrypt = pad_to_mod_16(string_to_bytearray(plaintext))
return encrypt_aes_cbc(to_encrypt, oracle_key, iv)
def cbc_encryption_oracle():
messages_encrypted = []
for message in messages:
message_to_encrypt = base64_to_bytearray(message)
message_to_encrypt_padded = pad_to_mod_16(message_to_encrypt)
ciphertext = encrypt_aes_cbc(message_to_encrypt_padded, ORACLE_KEY, ORACLE_IV)
messages_encrypted.append(ciphertext)
return messages_encrypted
def encrypt_user_data_cbc(user_data):
user_data = user_data.replace(";", "")
user_data = user_data.replace("=", "")
prefix = "comment1=cooking%20MCs;userdata="
suffix = ";comment2=%20like%20a%20pound%20of%20bacon"
plaintext = string_to_bytearray(prefix + user_data + suffix)
to_encrypt = pad_to_mod_16(plaintext)
ciphertext = encrypt_aes_cbc(to_encrypt, oracle_key, iv)
return ciphertext
def encryption_oracle_ecb_cbc(bt):
key = crypto_random_bytes(16)
iv = crypto_random_bytes(16)
mode = choice(['ecb', 'cbc'])
begin_pad = crypto_random_bytes(random_integer(5, 10))
end_pad = crypto_random_bytes(random_integer(5, 10))
to_encrypt = pad_to_mod_16(begin_pad + bt + end_pad)
if mode == 'ecb':
ciphertext = encrypt_aes_128_ecb(to_encrypt, key)
else:
ciphertext = encrypt_aes_cbc(to_encrypt, key, iv)
# do not cheat, use mode for validation only
return ciphertext, mode
def send_encrypted_message(self, message):
key = self.hkdf()
iv = crypto_random_bytes(16)
ciphertext = encrypt_aes_cbc(message, key, iv)
return ciphertext, iv