class TestCtr(unittest.TestCase):
"""
Tests AES-128 in CBC mode.
"""
def setUp(self):
self.aes = AES(b'\00' * 16)
self.iv = b'\01' * 16
self.message = b'my message'
def test_single_block(self):
""" Should be able to encrypt and decrypt single block messages. """
ciphertext = self.aes.encrypt_ctr(self.message, self.iv)
self.assertEqual(self.aes.decrypt_ctr(ciphertext, self.iv),
self.message)
# Since len(message) < block size, padding won't create a new block.
self.assertEqual(len(ciphertext), 16)
def test_wrong_iv(self):
""" CBC mode should verify the IVs are of correct length."""
with self.assertRaises(AssertionError):
self.aes.encrypt_ctr(self.message, b'short iv')
with self.assertRaises(AssertionError):
self.aes.encrypt_ctr(self.message, b'long iv' * 16)
with self.assertRaises(AssertionError):
self.aes.decrypt_ctr(self.message, b'short iv')
with self.assertRaises(AssertionError):
self.aes.decrypt_ctr(self.message, b'long iv' * 16)
def test_different_iv(self):
""" Different IVs should generate different ciphertexts. """
iv2 = b'\02' * 16
ciphertext1 = self.aes.encrypt_ctr(self.message, self.iv)
ciphertext2 = self.aes.encrypt_ctr(self.message, iv2)
self.assertNotEqual(ciphertext1, ciphertext2)
plaintext1 = self.aes.decrypt_ctr(ciphertext1, self.iv)
plaintext2 = self.aes.decrypt_ctr(ciphertext2, iv2)
self.assertEqual(plaintext1, plaintext2)
self.assertEqual(plaintext1, self.message)
def test_whole_block_padding(self):
""" When len(message) == block size, padding will add a block. """
block_message = b'M' * 16
ciphertext = self.aes.encrypt_ctr(block_message, self.iv)
self.assertEqual(len(ciphertext), 32)
self.assertEqual(self.aes.decrypt_ctr(ciphertext, self.iv),
block_message)
def test_long_message(self):
""" CBC should allow for messages longer than a single block. """
long_message = b'M' * 100
ciphertext = self.aes.encrypt_ctr(long_message, self.iv)
self.assertEqual(self.aes.decrypt_ctr(ciphertext, self.iv),
long_message)
class TestCtr(unittest.TestCase):
"""
Tests AES-128 in CBC mode.
"""
def setUp(self):
self.aes = AES(b'\x00' * 16)
self.iv = b'\x01' * 16
self.message = b'my message'
def test_single_block(self):
""" Should be able to encrypt and decrypt single block messages. """
ciphertext = self.aes.encrypt_ctr(self.message, self.iv)
self.assertEqual(self.aes.decrypt_ctr(
ciphertext, self.iv), self.message)
# Stream mode ciphers don't increase message size.
self.assertEqual(len(ciphertext), len(self.message))
def test_wrong_iv(self):
""" CBC mode should verify the IVs are of correct length."""
with self.assertRaises(AssertionError):
self.aes.encrypt_ctr(self.message, b'short iv')
with self.assertRaises(AssertionError):
self.aes.encrypt_ctr(self.message, b'long iv' * 16)
with self.assertRaises(AssertionError):
self.aes.decrypt_ctr(self.message, b'short iv')
with self.assertRaises(AssertionError):
self.aes.decrypt_ctr(self.message, b'long iv' * 16)
def test_different_iv(self):
""" Different IVs should generate different ciphertexts. """
iv2 = b'\x02' * 16
ciphertext1 = self.aes.encrypt_ctr(self.message, self.iv)
ciphertext2 = self.aes.encrypt_ctr(self.message, iv2)
self.assertNotEqual(ciphertext1, ciphertext2)
plaintext1 = self.aes.decrypt_ctr(ciphertext1, self.iv)
plaintext2 = self.aes.decrypt_ctr(ciphertext2, iv2)
self.assertEqual(plaintext1, plaintext2)
self.assertEqual(plaintext1, self.message)
def test_whole_block_padding(self):
block_message = b'M' * 16
ciphertext = self.aes.encrypt_ctr(block_message, self.iv)
self.assertEqual(len(ciphertext), len(block_message))
self.assertEqual(self.aes.decrypt_ctr(
ciphertext, self.iv), block_message)
def test_long_message(self):
long_message = b'M' * 100
ciphertext = self.aes.encrypt_ctr(long_message, self.iv)
self.assertEqual(self.aes.decrypt_ctr(
ciphertext, self.iv), long_message)
