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| # -*- coding: utf-8 -*- | |
| # | |
| # Cipher/AES.py : AES | |
| # | |
| # =================================================================== | |
| # The contents of this file are dedicated to the public domain. To | |
| # the extent that dedication to the public domain is not available, | |
| # everyone is granted a worldwide, perpetual, royalty-free, | |
| # non-exclusive license to exercise all rights associated with the | |
| # contents of this file for any purpose whatsoever. | |
| # No rights are reserved. | |
| # | |
| # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, | |
| # EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF | |
| # MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND | |
| # NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS | |
| # BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN | |
| # ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN | |
| # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE | |
| # SOFTWARE. | |
| # =================================================================== | |
| """ | |
| Module's constants for the modes of operation supported with AES: | |
| :var MODE_ECB: :ref:`Electronic Code Book (ECB) <ecb_mode>` | |
| :var MODE_CBC: :ref:`Cipher-Block Chaining (CBC) <cbc_mode>` | |
| :var MODE_CFB: :ref:`Cipher FeedBack (CFB) <cfb_mode>` | |
| :var MODE_OFB: :ref:`Output FeedBack (OFB) <ofb_mode>` | |
| :var MODE_CTR: :ref:`CounTer Mode (CTR) <ctr_mode>` | |
| :var MODE_OPENPGP: :ref:`OpenPGP Mode <openpgp_mode>` | |
| :var MODE_CCM: :ref:`Counter with CBC-MAC (CCM) Mode <ccm_mode>` | |
| :var MODE_EAX: :ref:`EAX Mode <eax_mode>` | |
| :var MODE_GCM: :ref:`Galois Counter Mode (GCM) <gcm_mode>` | |
| :var MODE_SIV: :ref:`Syntethic Initialization Vector (SIV) <siv_mode>` | |
| :var MODE_OCB: :ref:`Offset Code Book (OCB) <ocb_mode>` | |
| """ | |
| import sys | |
| from Crypto.Cipher import _create_cipher | |
| from Crypto.Util._raw_api import (load_pycryptodome_raw_lib, | |
| VoidPointer, SmartPointer, | |
| c_size_t, c_uint8_ptr) | |
| from Crypto.Util import _cpu_features | |
| from Crypto.Random import get_random_bytes | |
| _cproto = """ | |
| int AES_start_operation(const uint8_t key[], | |
| size_t key_len, | |
| void **pResult); | |
| int AES_encrypt(const void *state, | |
| const uint8_t *in, | |
| uint8_t *out, | |
| size_t data_len); | |
| int AES_decrypt(const void *state, | |
| const uint8_t *in, | |
| uint8_t *out, | |
| size_t data_len); | |
| int AES_stop_operation(void *state); | |
| """ | |
| # Load portable AES | |
| _raw_aes_lib = load_pycryptodome_raw_lib("Crypto.Cipher._raw_aes", | |
| _cproto) | |
| # Try to load AES with AES NI instructions | |
| try: | |
| _raw_aesni_lib = None | |
| if _cpu_features.have_aes_ni(): | |
| _raw_aesni_lib = load_pycryptodome_raw_lib("Crypto.Cipher._raw_aesni", | |
| _cproto.replace("AES", | |
| "AESNI")) | |
| # _raw_aesni may not have been compiled in | |
| except OSError: | |
| pass | |
| def _create_base_cipher(dict_parameters): | |
| """This method instantiates and returns a handle to a low-level | |
| base cipher. It will absorb named parameters in the process.""" | |
| use_aesni = dict_parameters.pop("use_aesni", True) | |
| try: | |
| key = dict_parameters.pop("key") | |
| except KeyError: | |
| raise TypeError("Missing 'key' parameter") | |
| if len(key) not in key_size: | |
| raise ValueError("Incorrect AES key length (%d bytes)" % len(key)) | |
| if use_aesni and _raw_aesni_lib: | |
| start_operation = _raw_aesni_lib.AESNI_start_operation | |
| stop_operation = _raw_aesni_lib.AESNI_stop_operation | |
| else: | |
| start_operation = _raw_aes_lib.AES_start_operation | |
| stop_operation = _raw_aes_lib.AES_stop_operation | |
| cipher = VoidPointer() | |
| result = start_operation(c_uint8_ptr(key), | |
| c_size_t(len(key)), | |
| cipher.address_of()) | |
| if result: | |
| raise ValueError("Error %X while instantiating the AES cipher" | |
| % result) | |
| return SmartPointer(cipher.get(), stop_operation) | |
| def _derive_Poly1305_key_pair(key, nonce): | |
| """Derive a tuple (r, s, nonce) for a Poly1305 MAC. | |
| If nonce is ``None``, a new 16-byte nonce is generated. | |
| """ | |
| if len(key) != 32: | |
| raise ValueError("Poly1305 with AES requires a 32-byte key") | |
| if nonce is None: | |
| nonce = get_random_bytes(16) | |
| elif len(nonce) != 16: | |
| raise ValueError("Poly1305 with AES requires a 16-byte nonce") | |
| s = new(key[:16], MODE_ECB).encrypt(nonce) | |
| return key[16:], s, nonce | |
| def new(key, mode, *args, **kwargs): | |
| """Create a new AES cipher. | |
| :param key: | |
| The secret key to use in the symmetric cipher. | |
| It must be 16, 24 or 32 bytes long (respectively for *AES-128*, | |
| *AES-192* or *AES-256*). | |
| For ``MODE_SIV`` only, it doubles to 32, 48, or 64 bytes. | |
| :type key: bytes/bytearray/memoryview | |
| :param mode: | |
| The chaining mode to use for encryption or decryption. | |
| If in doubt, use ``MODE_EAX``. | |
| :type mode: One of the supported ``MODE_*`` constants | |
| :Keyword Arguments: | |
| * **iv** (*bytes*, *bytearray*, *memoryview*) -- | |
| (Only applicable for ``MODE_CBC``, ``MODE_CFB``, ``MODE_OFB``, | |
| and ``MODE_OPENPGP`` modes). | |
| The initialization vector to use for encryption or decryption. | |
| For ``MODE_CBC``, ``MODE_CFB``, and ``MODE_OFB`` it must be 16 bytes long. | |
| For ``MODE_OPENPGP`` mode only, | |
| it must be 16 bytes long for encryption | |
| and 18 bytes for decryption (in the latter case, it is | |
| actually the *encrypted* IV which was prefixed to the ciphertext). | |
| If not provided, a random byte string is generated (you must then | |
| read its value with the :attr:`iv` attribute). | |
| * **nonce** (*bytes*, *bytearray*, *memoryview*) -- | |
| (Only applicable for ``MODE_CCM``, ``MODE_EAX``, ``MODE_GCM``, | |
| ``MODE_SIV``, ``MODE_OCB``, and ``MODE_CTR``). | |
| A value that must never be reused for any other encryption done | |
| with this key (except possibly for ``MODE_SIV``, see below). | |
| For ``MODE_EAX``, ``MODE_GCM`` and ``MODE_SIV`` there are no | |
| restrictions on its length (recommended: **16** bytes). | |
| For ``MODE_CCM``, its length must be in the range **[7..13]**. | |
| Bear in mind that with CCM there is a trade-off between nonce | |
| length and maximum message size. Recommendation: **11** bytes. | |
| For ``MODE_OCB``, its length must be in the range **[1..15]** | |
| (recommended: **15**). | |
| For ``MODE_CTR``, its length must be in the range **[0..15]** | |
| (recommended: **8**). | |
| For ``MODE_SIV``, the nonce is optional, if it is not specified, | |
| then no nonce is being used, which renders the encryption | |
| deterministic. | |
| If not provided, for modes other than ``MODE_SIV```, a random | |
| byte string of the recommended length is used (you must then | |
| read its value with the :attr:`nonce` attribute). | |
| * **segment_size** (*integer*) -- | |
| (Only ``MODE_CFB``).The number of **bits** the plaintext and ciphertext | |
| are segmented in. It must be a multiple of 8. | |
| If not specified, it will be assumed to be 8. | |
| * **mac_len** : (*integer*) -- | |
| (Only ``MODE_EAX``, ``MODE_GCM``, ``MODE_OCB``, ``MODE_CCM``) | |
| Length of the authentication tag, in bytes. | |
| It must be even and in the range **[4..16]**. | |
| The recommended value (and the default, if not specified) is **16**. | |
| * **msg_len** : (*integer*) -- | |
| (Only ``MODE_CCM``). Length of the message to (de)cipher. | |
| If not specified, ``encrypt`` must be called with the entire message. | |
| Similarly, ``decrypt`` can only be called once. | |
| * **assoc_len** : (*integer*) -- | |
| (Only ``MODE_CCM``). Length of the associated data. | |
| If not specified, all associated data is buffered internally, | |
| which may represent a problem for very large messages. | |
| * **initial_value** : (*integer* or *bytes/bytearray/memoryview*) -- | |
| (Only ``MODE_CTR``). | |
| The initial value for the counter. If not present, the cipher will | |
| start counting from 0. The value is incremented by one for each block. | |
| The counter number is encoded in big endian mode. | |
| * **counter** : (*object*) -- | |
| Instance of ``Crypto.Util.Counter``, which allows full customization | |
| of the counter block. This parameter is incompatible to both ``nonce`` | |
| and ``initial_value``. | |
| * **use_aesni** : (*boolean*) -- | |
| Use Intel AES-NI hardware extensions (default: use if available). | |
| :Return: an AES object, of the applicable mode. | |
| """ | |
| kwargs["add_aes_modes"] = True | |
| return _create_cipher(sys.modules[__name__], key, mode, *args, **kwargs) | |
| MODE_ECB = 1 | |
| MODE_CBC = 2 | |
| MODE_CFB = 3 | |
| MODE_OFB = 5 | |
| MODE_CTR = 6 | |
| MODE_OPENPGP = 7 | |
| MODE_CCM = 8 | |
| MODE_EAX = 9 | |
| MODE_SIV = 10 | |
| MODE_GCM = 11 | |
| MODE_OCB = 12 | |
| # Size of a data block (in bytes) | |
| block_size = 16 | |
| # Size of a key (in bytes) | |
| key_size = (16, 24, 32) | |