def encrypt_decrypt_CTR(text, key, nonce):
le_nonce = int_to_little_endian(nonce, 8)
keystream = ''
for i in range(len(text) / 16 + 1):
val = le_nonce + int_to_little_endian(i, 8)
keystream += chal7.encrypt_ECB(val, key)
return chal10.xor_data(text, keystream[:len(text)])
def encrypt_CBC(plaintext, key, iv):
ciphertext = ''
last_cipher = iv
plaintext = chal9.pad(plaintext, 16)
for i in range(len(plaintext) / BLOCK_SIZE):
plain_block = plaintext[i * BLOCK_SIZE:(i + 1) * BLOCK_SIZE]
plain_block = xor_data(plain_block, last_cipher)
last_cipher = chal7.encrypt_ECB(plain_block, key)
ciphertext += last_cipher
return ciphertext
def encryption_oracle(plaintext):
aes_key = get_random_bytes(16)
plaintext = get_random_bytes(random.randint(
5, 10)) + plaintext + get_random_bytes(random.randint(5, 10))
ecb_flag = (0 == random.randint(0, 1))
#print ecb_flag
if ecb_flag:
#ecb encryption
plaintext = chal9.pad(plaintext, 16)
return chal7.encrypt_ECB(plaintext, aes_key)
else:
iv = get_random_bytes(16)
return chal10.encrypt_CBC(plaintext, aes_key, iv)
def encryption_oracle(plaintext): plaintext = plaintext+base64.b64decode(unknown_string) plaintext = chal9.pad(plaintext,16) return chal7.encrypt_ECB(plaintext,KEY)
def encrypt(plaintext, key):
plaintext = chal9.pad(plaintext, 16)
return chal7.encrypt_ECB(plaintext, key)