def value(self):
random_generator = RandomByteGenerator()
key = random_generator.value(self.BLOCK_SIZE)
iv = random_generator.value(self.BLOCK_SIZE)
ciphertext = AES(key).encrypt(self.plaintext, mode=CBC(iv))
oracle = CBCPaddingOracle(key, iv)
return CBCPaddingOracleAttack(oracle).value(ciphertext, iv)
class RandomECB_CBCEncrypter(object):
def __init__(self, block_size):
self.block_size = block_size
self.random_generator = RandomByteGenerator()
def get_mode(self):
# To use after encryption in order to confirm that the oracle works.
return self.mode.name()
def _prepare_plaintext(self, plaintext):
header = self.random_generator.value(random.randint(5,10))
footer = self.random_generator.value(random.randint(5,10))
return '%s%s%s' % (header, plaintext, footer)
def _get_random_mode(self):
if random.random() >= 0.5:
mode = ECB(block_size=self.block_size)
else:
random_iv = self.random_generator.value(self.block_size)
mode = CBC(iv=random_iv, block_size=self.block_size)
return mode
def encrypt(self, plaintext):
plaintext = self._prepare_plaintext(plaintext)
key = self.random_generator.value(self.block_size)
self.mode = self._get_random_mode()
return AES(key).encrypt(plaintext, mode=self.mode)
def value(self):
random_generator = RandomByteGenerator()
key = random_generator.value(self.BLOCK_SIZE)
iv = random_generator.value(self.BLOCK_SIZE)
ciphertext = AES(key).encrypt(self.plaintext, mode=CBC(iv))
oracle = CBCPaddingOracle(key, iv)
return CBCPaddingOracleAttack(oracle).value(ciphertext, iv)
def _build_padding(self, size):
byte_generator = RandomByteGenerator()
padding = byte_generator.value(size)
return padding.replace('\x00', byte_generator.value(1))