Python Crypto.Cipher.AES.MODE_CTR Examples

def triple_des_encrypt(
        self,
        key: str,
        iv: str = "0000000000000000",
        mode: str = "CBC",
        hex_key: bool = False,
        hex_iv: bool = True,
    ):
        """Encrypt raw state with Triple DES

        Triple DES applies DES three times to each block to increase key size. Key: 
        Triple DES uses a key length of 24 bytes (192 bits).<br>DES uses a key length 
        of 8 bytes (64 bits).<br><br>You can generate a password-based key using one 
        of the KDF operations. IV: The Initialization Vector should be 8 bytes long. 
        If not entered, it will default to 8 null bytes. Padding: In CBC and ECB 
        mode, PKCS#7 padding will be used.
        
        Args:
            key (str): Required. The secret key
            iv (str, optional): IV for certain modes only. Defaults to '0000000000000000'.
            mode (str, optional): Encryption mode. Defaults to 'CBC'.
            hex_key (bool, optional): If the secret key is a hex string. Defaults to False.
            hex_iv (bool, optional): If the IV is a hex string. Defaults to True.
        
        Returns:
            Chepy: The Chepy object. 

        Examples:
            >>> Chepy("some data").triple_des_encrypt("super secret password !!", mode="ECB").o
            b"f8b27a0d8c837edc8fb00ea85f502fb4"
        """

        self.__check_mode(mode)

        key, iv = self._convert_key(key, iv, hex_key, hex_iv)

        if mode == "CBC":
            cipher = DES3.new(key, mode=DES3.MODE_CBC, iv=iv)
            self.state = cipher.encrypt(pad(self._convert_to_bytes(), 8))
            return self
        elif mode == "ECB":
            cipher = DES3.new(key, mode=DES3.MODE_ECB)
            self.state = cipher.encrypt(pad(self._convert_to_bytes(), 8))
            return self
        elif mode == "CTR":
            cipher = DES3.new(key, mode=DES3.MODE_CTR, nonce=b"")
            self.state = cipher.encrypt(self._convert_to_bytes())
            return self
        elif mode == "OFB":
            cipher = DES3.new(key, mode=DES3.MODE_OFB, iv=iv)
            self.state = cipher.encrypt(self._convert_to_bytes())
            return self 

def decrypt_file(self, dec_material, data):
        if not self._good:
            logging.warning('well, it is hard to decrypt with a wrong key.')

        if not dec_material.iv:
            logging.error('cannot decrypt with an empty iv!')
            return None

        counter_obj = Counter.new(
            128,
            initial_value=int.from_bytes(dec_material.iv, byteorder='big'),
            little_endian=False)

        decryptor = AES.new(
            self._bkey_sha256, mode=AES.MODE_CTR, counter=counter_obj)
        return decryptor.decrypt(data)

# --- DecryptInfo ------------------------------------------------------------- 

def test_initial_value_bytes_parameter(self):
        # Same result as when passing an integer
        cipher1 = AES.new(self.key_128, AES.MODE_CTR,
                          nonce=self.nonce_64,
                          initial_value=b"\x00"*6+b"\xFF\xFF")
        cipher2 = AES.new(self.key_128, AES.MODE_CTR,
                          nonce=self.nonce_64, initial_value=0xFFFF)
        pt = get_tag_random("plaintext", 65536)
        self.assertEqual(cipher1.encrypt(pt), cipher2.encrypt(pt))

        # Fail if the iv is too large
        self.assertRaises(ValueError, AES.new, self.key_128, AES.MODE_CTR,
                          initial_value=b"5"*17)
        self.assertRaises(ValueError, AES.new, self.key_128, AES.MODE_CTR,
                          nonce=self.nonce_64, initial_value=b"5"*9)

        # Fail if the iv is too short
        self.assertRaises(ValueError, AES.new, self.key_128, AES.MODE_CTR,
                          initial_value=b"5"*15)
        self.assertRaises(ValueError, AES.new, self.key_128, AES.MODE_CTR,
                          nonce=self.nonce_64, initial_value=b"5"*7) 

def iter_transform(filename, key):
    """Generate encrypted file with given key.

    This generator function reads the file
    in chunks and encrypts them using AES-CTR,
    with the specified key.

    :param filename: The name of the file to encrypt.
    :type filename: str
    :param key: The key used to encrypt the file.
    :type key: str
    :returns: A generator that produces encrypted file chunks.
    :rtype: generator
    """
    # We are not specifying the IV here.
    aes = AES.new(key, AES.MODE_CTR, counter=Counter.new(128))

    with open(filename, 'rb+') as f:
        for chunk in iter(lambda: f.read(CHUNK_SIZE), b''):
            yield aes.encrypt(chunk), f 

def test_wrap_around(self):
        # Counter is only 8 bits, so we can only encrypt/decrypt 256 blocks (=4096 bytes)
        counter = Counter.new(8, prefix=bchr(9) * 15)
        max_bytes = 4096

        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=counter)
        cipher.encrypt(b'9' * max_bytes)
        self.assertRaises(OverflowError, cipher.encrypt, b'9')

        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=counter)
        self.assertRaises(OverflowError, cipher.encrypt, b'9' * (max_bytes + 1))

        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=counter)
        cipher.decrypt(b'9' * max_bytes)
        self.assertRaises(OverflowError, cipher.decrypt, b'9')

        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=counter)
        self.assertRaises(OverflowError, cipher.decrypt, b'9' * (max_bytes + 1)) 

def test_aes_128(self):
        plaintext =     '6bc1bee22e409f96e93d7e117393172a' +\
                        'ae2d8a571e03ac9c9eb76fac45af8e51' +\
                        '30c81c46a35ce411e5fbc1191a0a52ef' +\
                        'f69f2445df4f9b17ad2b417be66c3710'
        ciphertext =    '874d6191b620e3261bef6864990db6ce' +\
                        '9806f66b7970fdff8617187bb9fffdff' +\
                        '5ae4df3edbd5d35e5b4f09020db03eab' +\
                        '1e031dda2fbe03d1792170a0f3009cee'
        key =           '2b7e151628aed2a6abf7158809cf4f3c'
        counter =       Counter.new(nbits=16,
                                    prefix=unhexlify('f0f1f2f3f4f5f6f7f8f9fafbfcfd'),
                                    initial_value=0xfeff)

        key = unhexlify(key)
        plaintext = unhexlify(plaintext)
        ciphertext = unhexlify(ciphertext)

        cipher = AES.new(key, AES.MODE_CTR, counter=counter)
        self.assertEqual(cipher.encrypt(plaintext), ciphertext)
        cipher = AES.new(key, AES.MODE_CTR, counter=counter)
        self.assertEqual(cipher.decrypt(ciphertext), plaintext) 

def test_output_param_neg(self):

        pt = b'5' * 16
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        ct = cipher.encrypt(pt)

        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        self.assertRaises(TypeError, cipher.encrypt, pt, output=b'0'*16)
        
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        self.assertRaises(TypeError, cipher.decrypt, ct, output=b'0'*16)

        shorter_output = bytearray(15)
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        self.assertRaises(ValueError, cipher.encrypt, pt, output=shorter_output)
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        self.assertRaises(ValueError, cipher.decrypt, ct, output=shorter_output) 

def decrypt_large_package(self, dec_material, entry):
        if not self._good:
            logging.warning('well, it is hard to decrypt with a wrong key.')

        if not dec_material.encMsgV3:
            logging.error('cannot decrypt with an empty encMsgV3!')
            return None

        salt = dec_material.encMsgV3[:32]
        counter_iv = dec_material.encMsgV3[32:]

        key = PBKDF2(self._bkey, salt, Decryptor.dklen, Decryptor.count,
                     Decryptor.prf, hmac_hash_module=None)

        counter_obj = Counter.new(128, initial_value=int.from_bytes(
            counter_iv, byteorder='big'), little_endian=False)

        decryptor = AES.new(key, mode=AES.MODE_CTR, counter=counter_obj)
        data_len = entry.stat().st_size
        with open(entry, 'rb') as entry_fd:
            for x in range(0, data_len, self.chunk_size):
                logging.debug('decrypting chunk %d of %s', x, entry)
                data = entry_fd.read(self.chunk_size)
                yield decryptor.decrypt(data) 

def decrypt_package(self, dec_material, data):
        if not self._good:
            logging.warning('well, it is hard to decrypt with a wrong key.')

        if not dec_material.encMsgV3:
            logging.error('cannot decrypt with an empty encMsgV3!')
            return None

        salt = dec_material.encMsgV3[:32]
        counter_iv = dec_material.encMsgV3[32:]

        key = PBKDF2(self._bkey, salt, Decryptor.dklen, Decryptor.count,
                     Decryptor.prf, hmac_hash_module=None)

        counter_obj = Counter.new(128, initial_value=int.from_bytes(
            counter_iv, byteorder='big'), little_endian=False)

        decryptor = AES.new(key, mode=AES.MODE_CTR, counter=counter_obj)
        return decryptor.decrypt(data) 

def test_aes_192(self):
        plaintext =     '6bc1bee22e409f96e93d7e117393172a' +\
                        'ae2d8a571e03ac9c9eb76fac45af8e51' +\
                        '30c81c46a35ce411e5fbc1191a0a52ef' +\
                        'f69f2445df4f9b17ad2b417be66c3710'
        ciphertext =    '1abc932417521ca24f2b0459fe7e6e0b' +\
                        '090339ec0aa6faefd5ccc2c6f4ce8e94' +\
                        '1e36b26bd1ebc670d1bd1d665620abf7' +\
                        '4f78a7f6d29809585a97daec58c6b050'
        key =           '8e73b0f7da0e6452c810f32b809079e562f8ead2522c6b7b'
        counter =       Counter.new(nbits=16,
                                    prefix=unhexlify('f0f1f2f3f4f5f6f7f8f9fafbfcfd'),
                                    initial_value=0xfeff)

        key = unhexlify(key)
        plaintext = unhexlify(plaintext)
        ciphertext = unhexlify(ciphertext)

        cipher = AES.new(key, AES.MODE_CTR, counter=counter)
        self.assertEqual(cipher.encrypt(plaintext), ciphertext)
        cipher = AES.new(key, AES.MODE_CTR, counter=counter)
        self.assertEqual(cipher.decrypt(ciphertext), plaintext) 

def test_output_param(self):

        pt = b'5' * 16
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        ct = cipher.encrypt(pt)

        output = bytearray(16)
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        res = cipher.encrypt(pt, output=output)
        self.assertEqual(ct, output)
        self.assertEqual(res, None)
        
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        res = cipher.decrypt(ct, output=output)
        self.assertEqual(pt, output)
        self.assertEqual(res, None) 

def des_encrypt(
        self,
        key: str,
        iv: str = "0000000000000000",
        mode: str = "CBC",
        hex_key: bool = False,
        hex_iv: bool = True,
    ):
        """Encrypt raw state with DES

        DES is a previously dominant algorithm for encryption, and was published 
        as an official U.S. Federal Information Processing Standard (FIPS). It is 
        now considered to be insecure due to its small key size. DES uses a key 
        length of 8 bytes (64 bits).<br>Triple DES uses a key length of 24 bytes. 
        You can generate a password-based key using one of the KDF operations. 
        The Initialization Vector should be 8 bytes long. If not entered, it will 
        default to 8 null bytes. Padding: In CBC and ECB mode, PKCS#7 padding will be used.
        
        Args:
            key (str): Required. The secret key
            iv (str, optional): IV for certain modes only. Defaults to '0000000000000000'.
            mode (str, optional): Encryption mode. Defaults to 'CBC'.
            hex_key (bool, optional): If the secret key is a hex string. Defaults to False.
            hex_iv (bool, optional): If the IV is a hex string. Defaults to True.
        
        Returns:
            Chepy: The Chepy object. 

        Examples:
            >>> Chepy("some data").des_encrypt("70617373776f7264", hex_key=True).o
            b"1ee5cb52954b211d1acd6e79c598baac"

            To encrypt using a differnt mode

            >>> Chepy("some data").des_encrypt("password", mode="CTR").o
            b"0b7399049b0267d93d"
        """

        self.__check_mode(mode)

        key, iv = self._convert_key(key, iv, hex_key, hex_iv)

        if mode == "CBC":
            cipher = DES.new(key, mode=DES.MODE_CBC, iv=iv)
            self.state = cipher.encrypt(pad(self._convert_to_bytes(), 8))
            return self
        elif mode == "ECB":
            cipher = DES.new(key, mode=DES.MODE_ECB)
            self.state = cipher.encrypt(pad(self._convert_to_bytes(), 8))
            return self
        elif mode == "CTR":
            cipher = DES.new(key, mode=DES.MODE_CTR, nonce=b"")
            self.state = cipher.encrypt(self._convert_to_bytes())
            return self
        elif mode == "OFB":
            cipher = DES.new(key, mode=DES.MODE_OFB, iv=iv)
            self.state = cipher.encrypt(self._convert_to_bytes())
            return self 

def test_output_param_memoryview(self):
        
        pt = b'5' * 16
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        ct = cipher.encrypt(pt)

        output = memoryview(bytearray(16))
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        cipher.encrypt(pt, output=output)
        self.assertEqual(ct, output)
        
        cipher = AES.new(b'4'*16, AES.MODE_CTR, nonce=self.nonce_64)
        cipher.decrypt(ct, output=output)
        self.assertEqual(pt, output) 

def seek(self, offset):
		self.ctr = Counter.new(64, prefix=self.nonce[0:8], initial_value=(offset >> 4))
		self.aes = AES.new(self.key, AES.MODE_CTR, counter=self.ctr) 

def test_bytearray(self):
        data = b"1" * 16
        iv = b"\x00" * 6 + b"\xFF\xFF"

        # Encrypt
        cipher1 = AES.new(self.key_128, AES.MODE_CTR,
                          nonce=self.nonce_64,
                          initial_value=iv)
        ref1 = cipher1.encrypt(data)

        cipher2 = AES.new(self.key_128, AES.MODE_CTR,
                          nonce=bytearray(self.nonce_64),
                          initial_value=bytearray(iv))
        ref2 = cipher2.encrypt(bytearray(data))

        self.assertEqual(ref1, ref2)
        self.assertEqual(cipher1.nonce, cipher2.nonce)

        # Decrypt
        cipher3 = AES.new(self.key_128, AES.MODE_CTR,
                          nonce=self.nonce_64,
                          initial_value=iv)
        ref3 = cipher3.decrypt(data)

        cipher4 = AES.new(self.key_128, AES.MODE_CTR,
                          nonce=bytearray(self.nonce_64),
                          initial_value=bytearray(iv))
        ref4 = cipher4.decrypt(bytearray(data))

        self.assertEqual(ref3, ref4) 

def test_iv_with_matching_length(self):
        self.assertRaises(ValueError, AES.new, self.key_128, AES.MODE_CTR,
                          counter=Counter.new(120))
        self.assertRaises(ValueError, AES.new, self.key_128, AES.MODE_CTR,
                          counter=Counter.new(136)) 

def __init__(self, key, nonce, offset = 0):
		self.key = key
		self.nonce = nonce
		self.seek(offset)
		#self.aes = AES.new(self.key, AES.MODE_CTR, initial_value=self.ctr[0:8]) 

def test_nonce_parameter(self):
        # Nonce parameter becomes nonce attribute
        cipher1 = AES.new(self.key_128, AES.MODE_CTR, nonce=self.nonce_64)
        self.assertEqual(cipher1.nonce, self.nonce_64)

        counter = Counter.new(64, prefix=self.nonce_64, initial_value=0)
        cipher2 = AES.new(self.key_128, AES.MODE_CTR, counter=counter)
        self.assertEqual(cipher1.nonce, cipher2.nonce)

        pt = get_tag_random("plaintext", 65536)
        self.assertEqual(cipher1.encrypt(pt), cipher2.encrypt(pt))

        # Nonce is implicitly created (for AES) when no parameters are passed
        nonce1 = AES.new(self.key_128, AES.MODE_CTR).nonce
        nonce2 = AES.new(self.key_128, AES.MODE_CTR).nonce
        self.assertNotEqual(nonce1, nonce2)
        self.assertEqual(len(nonce1), 8)

        # Nonce can be zero-length
        cipher = AES.new(self.key_128, AES.MODE_CTR, nonce=b"")
        self.assertEqual(b"", cipher.nonce)
        cipher.encrypt(b'0'*300)

        # Nonce and Counter are mutually exclusive
        self.assertRaises(TypeError, AES.new, self.key_128, AES.MODE_CTR,
                          counter=self.ctr_128, nonce=self.nonce_64) 

def test_nonce_attribute(self):
        # Nonce attribute is the prefix passed to Counter (DES3)
        cipher = DES3.new(self.key_192, DES3.MODE_CTR, counter=self.ctr_64)
        self.assertEqual(cipher.nonce, self.nonce_32)

        # Nonce attribute is the prefix passed to Counter (AES)
        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=self.ctr_128)
        self.assertEqual(cipher.nonce, self.nonce_64)

        # Nonce attribute is not defined if suffix is used in Counter
        counter = Counter.new(64, prefix=self.nonce_32, suffix=self.nonce_32)
        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=counter)
        self.failIf(hasattr(cipher, "nonce")) 

def test_invalid_counter_parameter(self):
        # Counter object is required for ciphers with short block size
        self.assertRaises(TypeError, DES3.new, self.key_192, AES.MODE_CTR)
        # Positional arguments are not allowed (Counter must be passed as
        # keyword)
        self.assertRaises(TypeError, AES.new, self.key_128, AES.MODE_CTR, self.ctr_128) 

def test_loopback_64(self):
        cipher = DES3.new(self.key_192, DES3.MODE_CTR, counter=self.ctr_64)
        pt = get_tag_random("plaintext", 8 * 100)
        ct = cipher.encrypt(pt)

        cipher = DES3.new(self.key_192, DES3.MODE_CTR, counter=self.ctr_64)
        pt2 = cipher.decrypt(ct)
        self.assertEqual(pt, pt2) 

def test_loopback_128(self):
        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=self.ctr_128)
        pt = get_tag_random("plaintext", 16 * 100)
        ct = cipher.encrypt(pt)

        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=self.ctr_128)
        pt2 = cipher.decrypt(ct)
        self.assertEqual(pt, pt2) 

def new_cipher(self, key, iv):
        """
        @param key:    the secret key, a byte string
        @param iv:     the initialization vector, a byte string
        @return:    an initialized cipher object for this algo
        """
        if (hasattr(self.cipher, 'MODE_CTR') and self.mode == self.cipher.MODE_CTR
            or hasattr(self.cipher, 'MODE_GCM') and self.mode == self.cipher.MODE_GCM):
            # in counter mode, the "iv" must be incremented for each block
            # it is calculated like this:
            # +---------+------------------+---------+
            # |  nonce  |        IV        | counter |
            # +---------+------------------+---------+
            #   m bytes       n bytes        4 bytes
            # <-------------------------------------->
            #               block_size
            nonce_size = self.cipher.block_size - self.iv_size - 4

            # instead of asking for an extra parameter, we extract the last
            # nonce_size bytes of the key and use them as the nonce.
            # +----------------------------+---------+
            # |        cipher key          |  nonce  |
            # +----------------------------+---------+
            #                              <--------->
            #                               nonce_size
            cipher_key, nonce = key[:-nonce_size], key[-nonce_size:]

            return self.cipher.new(cipher_key, self.mode,
                                   counter=Counter.new(4 * 8, prefix=nonce + iv))
        else:
            return self.cipher.new(key, self.mode, iv) 

def encrypt_aes_ctr(value, key, iv):
    ctr = Counter.new(128, initial_value=iv, allow_wraparound=True)
    encryptor = AES.new(key, AES.MODE_CTR, counter=ctr)
    ciphertext = encryptor.encrypt(value)
    return ciphertext


#
# Utility
# 

def decrypt_aes_ctr(ciphertext, key, iv):
    ctr = Counter.new(128, initial_value=iv, allow_wraparound=True)
    encryptor = AES.new(key, AES.MODE_CTR, counter=ctr)
    return encryptor.decrypt(ciphertext) 

def __init__(self, key, iv):
		self.key = key
		self.iv = iv
		
		self.ctr = Counter.new(128, initial_value=int(iv.encode("hex"), 16))
		self.cipher = AES.new(key, AES.MODE_CTR, counter=self.ctr) 

def __init__(self, stash_key, manager_provider, aws_profile=None, aws_region=None, aws_bucket=None):
        check_latest_version()

        self._aws_manager = manager_provider.aws_manager(aws_profile, aws_region or 'us-east-1')

        if aws_bucket is None:
            deployment_bucket_name = 'novastash_%s' % self._aws_manager.account_alias
        else:
            deployment_bucket_name = aws_bucket

        key = "%s.txt.enc" % stash_key
        existing_stash = self._aws_manager.s3_get(deployment_bucket_name, key)

        if existing_stash is None:
            raise NovaError("No stash '%s' found!" % stash_key)
        else:
            contents = existing_stash['Body'].read()
            metadata = existing_stash['Metadata']
            encryption_key = metadata['encryption-key']
            kms_response = self._aws_manager.kms_decrypt(b64decode(encryption_key), {})

            key = kms_response['Plaintext'][:32]
            hmac_key = kms_response['Plaintext'][32:]
            hmac = HMAC(hmac_key, msg=b64decode(contents), digestmod=SHA256)

            if hmac.hexdigest() != metadata['hmac']:
                raise NovaError("Computed HMAC on '%s' does not match stored HMAC" % stash_key)

            dec_ctr = Counter.new(128)
            decryptor = AES.new(key, AES.MODE_CTR, counter=dec_ctr)
            print(decryptor.decrypt(b64decode(contents)).decode("utf-8")) 

def test_loopback_128(self):
        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=self.ctr_128)
        pt = get_tag_random("plaintext", 16 * 100)
        ct = cipher.encrypt(pt)

        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=self.ctr_128)
        pt2 = cipher.decrypt(ct)
        self.assertEqual(pt, pt2) 

def setup(self):
        from Crypto.Cipher import AES
        self.cipher = AES.new(self.key, AES.MODE_CTR, nonce=b'', initial_value=self.iv) 

def test_block_size_128(self):
        cipher = AES.new(self.key_128, AES.MODE_CTR, counter=self.ctr_128)
        self.assertEqual(cipher.block_size, AES.block_size)