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env/lib/python3.12/site-packages/Crypto/Cipher/CAST.py

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+# -*- coding: utf-8 -*-
+#
+#  Cipher/CAST.py : CAST
+#
+# ===================================================================
+# 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 CAST:
+
+: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_EAX: :ref:`EAX Mode <eax_mode>`
+"""
+
+import sys
+
+from Crypto.Cipher import _create_cipher
+from Crypto.Util.py3compat import byte_string
+from Crypto.Util._raw_api import (load_pycryptodome_raw_lib,
+                                  VoidPointer, SmartPointer,
+                                  c_size_t, c_uint8_ptr)
+
+_raw_cast_lib = load_pycryptodome_raw_lib(
+                    "Crypto.Cipher._raw_cast",
+                    """
+                    int CAST_start_operation(const uint8_t key[],
+                                             size_t key_len,
+                                             void **pResult);
+                    int CAST_encrypt(const void *state,
+                                     const uint8_t *in,
+                                     uint8_t *out,
+                                     size_t data_len);
+                    int CAST_decrypt(const void *state,
+                                     const uint8_t *in,
+                                     uint8_t *out,
+                                     size_t data_len);
+                    int CAST_stop_operation(void *state);
+                    """)
+
+
+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."""
+
+    try:
+        key = dict_parameters.pop("key")
+    except KeyError:
+        raise TypeError("Missing 'key' parameter")
+
+    if len(key) not in key_size:
+        raise ValueError("Incorrect CAST key length (%d bytes)" % len(key))
+
+    start_operation = _raw_cast_lib.CAST_start_operation
+    stop_operation = _raw_cast_lib.CAST_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 CAST cipher"
+                         % result)
+
+    return SmartPointer(cipher.get(), stop_operation)
+
+
+def new(key, mode, *args, **kwargs):
+    """Create a new CAST cipher
+
+    :param key:
+        The secret key to use in the symmetric cipher.
+        Its length can vary from 5 to 16 bytes.
+    :type key: bytes, bytearray, memoryview
+
+    :param mode:
+        The chaining mode to use for encryption or decryption.
+    :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 8 bytes long.
+
+            For ``MODE_OPENPGP`` mode only,
+            it must be 8 bytes long for encryption
+            and 10 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_EAX`` and ``MODE_CTR``).
+
+            A value that must never be reused for any other encryption done
+            with this key.
+
+            For ``MODE_EAX`` there are no
+            restrictions on its length (recommended: **16** bytes).
+
+            For ``MODE_CTR``, its length must be in the range **[0..7]**.
+
+            If not provided for ``MODE_EAX``, a random byte string is generated (you
+            can read it back via the ``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``)
+            Length of the authentication tag, in bytes.
+            It must be no longer than 8 (default).
+
+        *   **initial_value** : (*integer*) --
+            (Only ``MODE_CTR``). The initial value for the counter within
+            the counter block. By default it is **0**.
+
+    :Return: a CAST object, of the applicable mode.
+    """
+
+    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_EAX = 9
+
+# Size of a data block (in bytes)
+block_size = 8
+# Size of a key (in bytes)
+key_size = range(5, 16 + 1)