def build_profile(userdata):
plaintext = ('comment1=cooking%20MCs;userdata=' + quote(userdata) +
';comment2=%20like%20a%20pound%20of%20bacon')
plaintext = bytearray(plaintext, encoding='utf-8')
plaintext = pkcs7padding(plaintext)
ciphertext = aes_cbc_encrypt(plaintext, random_key, random_iv)
return ciphertext
def encrypt_random(plaintext):
bytes_to_add = random.randint(5, 10)
plaintext = challenge9.pkcs7padding(
random_string(bytes_to_add) + plaintext + random_string(bytes_to_add))
ecb = random.randint(0, 1)
if ecb:
aes = AES.new(random_string(16))
ciphertext = aes.encrypt(plaintext)
else:
ciphertext = challenge10.aes_cbc_encrypt(plaintext, random_string(16),
random_string(16))
return ciphertext, (ecb == 1)
def encryption_oracle(input):
random_key = os.urandom(16)
modified_input = os.urandom(randrange(5,11)) + input + os.urandom(randrange(5,11))
encrypted = bytearray()
if randrange(0,2) == 1:
# do cbc
iv = os.urandom(16)
encrypted = aes_cbc_encrypt(modified_input, random_key, iv)
else:
#do ecb
encrypted = encrypt_block(pad(modified_input), random_key)
return bytearray(encrypted)
def f1(s):
# quote out ; and = in s
s = s.replace(';', '";"')
s = s.replace('=', '"="')
res = PREPEND + s + APPEND
# pad
res_padded = pkcs7_pad(res, BLK_SZ)
# encrypt under random AES key
k = gen_aes_key()
iv = secrets.token_bytes(BLK_SZ)
res_enc = aes_cbc_encrypt(res_padded, k, iv)
return k, res_enc, iv
def encryption_oracle(pt):
"""
For the input @pt, pads it with 5-10 bytes on both sides, then encrypts it
with either AES in ECB mode or AES in CBC mode with equal probability. The
key and IV are randomly generated 16-byte strings.
"""
key = rand_bytes(16)
iv = rand_bytes(16) # In case the mode is CBC. Generate this before
# choosing the mode to protect against timing attacks.
padded_pt = rand_bytes_range(5, 10) + pt + rand_bytes_range(5, 10)
if random.randint(0, 1) == 0:
# print True # Uncomment to check the oracle detector
return aes_ecb_encrypt(key, padded_pt)
else:
# print False # Uncomment to check the oracle detector
return aes_cbc_encrypt(key, padded_pt, iv)
def encryption_oracle(x):
if type(x) == str:
x = bytearray(x, "utf-8")
bytes_append_len = 5 + secrets.randbelow(6)
bytes_prepend_len = 5 + secrets.randbelow(6)
bytes_appended = bytearray(secrets.token_bytes(bytes_append_len))
bytes_prepended = bytearray(secrets.token_bytes(bytes_prepend_len))
pt = pkcs7_pad(bytes_prepended + x + bytes_appended, 16)
encryption_scheme = secrets.randbelow(2)
if (encryption_scheme == ECB_MODE):
# do ECB
ct = encrypt_aes_ecb(pt, gen_aes_key())
elif (encryption_scheme == CBC_MODE):
# do CBC
ct = aes_cbc_encrypt(pt, gen_aes_key(), secrets.token_bytes(BLK_SZ))
return ct, encryption_scheme
def encrypt_cbc_random():
plaintext = binascii.a2b_base64(random.choice(possible_b64_plaintexts))
iv = random_string(AES.block_size)
return aes_cbc_encrypt(plaintext, random_key, iv), iv
def encrypt(self, pt):
return aes_cbc_encrypt(self.__key, self.PREFIX + pt + self.SUFFIX,
self.__iv)