second commit

env/lib/python3.11/site-packages/Crypto/Cipher/ARC4.py

@@ -0,0 +1,136 @@
+# -*- coding: utf-8 -*-
+#
+#  Cipher/ARC4.py : ARC4
+#
+# ===================================================================
+# 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.
+# ===================================================================
+
+from Crypto.Util._raw_api import (load_pycryptodome_raw_lib, VoidPointer,
+                                  create_string_buffer, get_raw_buffer,
+                                  SmartPointer, c_size_t, c_uint8_ptr)
+
+
+_raw_arc4_lib = load_pycryptodome_raw_lib("Crypto.Cipher._ARC4", """
+                    int ARC4_stream_encrypt(void *rc4State, const uint8_t in[],
+                                            uint8_t out[], size_t len);
+                    int ARC4_stream_init(uint8_t *key, size_t keylen,
+                                         void **pRc4State);
+                    int ARC4_stream_destroy(void *rc4State);
+                    """)
+
+
+class ARC4Cipher:
+    """ARC4 cipher object. Do not create it directly. Use
+    :func:`Crypto.Cipher.ARC4.new` instead.
+    """
+
+    def __init__(self, key, *args, **kwargs):
+        """Initialize an ARC4 cipher object
+
+        See also `new()` at the module level."""
+
+        if len(args) > 0:
+            ndrop = args[0]
+            args = args[1:]
+        else:
+            ndrop = kwargs.pop('drop', 0)
+
+        if len(key) not in key_size:
+            raise ValueError("Incorrect ARC4 key length (%d bytes)" %
+                             len(key))
+
+        self._state = VoidPointer()
+        result = _raw_arc4_lib.ARC4_stream_init(c_uint8_ptr(key),
+                                                c_size_t(len(key)),
+                                                self._state.address_of())
+        if result != 0:
+            raise ValueError("Error %d while creating the ARC4 cipher"
+                             % result)
+        self._state = SmartPointer(self._state.get(),
+                                   _raw_arc4_lib.ARC4_stream_destroy)
+
+        if ndrop > 0:
+            # This is OK even if the cipher is used for decryption,
+            # since encrypt and decrypt are actually the same thing
+            # with ARC4.
+            self.encrypt(b'\x00' * ndrop)
+
+        self.block_size = 1
+        self.key_size = len(key)
+
+    def encrypt(self, plaintext):
+        """Encrypt a piece of data.
+
+        :param plaintext: The data to encrypt, of any size.
+        :type plaintext: bytes, bytearray, memoryview
+        :returns: the encrypted byte string, of equal length as the
+          plaintext.
+        """
+
+        ciphertext = create_string_buffer(len(plaintext))
+        result = _raw_arc4_lib.ARC4_stream_encrypt(self._state.get(),
+                                                   c_uint8_ptr(plaintext),
+                                                   ciphertext,
+                                                   c_size_t(len(plaintext)))
+        if result:
+            raise ValueError("Error %d while encrypting with RC4" % result)
+        return get_raw_buffer(ciphertext)
+
+    def decrypt(self, ciphertext):
+        """Decrypt a piece of data.
+
+        :param ciphertext: The data to decrypt, of any size.
+        :type ciphertext: bytes, bytearray, memoryview
+        :returns: the decrypted byte string, of equal length as the
+          ciphertext.
+        """
+
+        try:
+            return self.encrypt(ciphertext)
+        except ValueError as e:
+            raise ValueError(str(e).replace("enc", "dec"))
+
+
+def new(key, *args, **kwargs):
+    """Create a new ARC4 cipher.
+
+    :param key:
+        The secret key to use in the symmetric cipher.
+        Its length must be in the range ``[1..256]``.
+        The recommended length is 16 bytes.
+    :type key: bytes, bytearray, memoryview
+
+    :Keyword Arguments:
+        *   *drop* (``integer``) --
+            The amount of bytes to discard from the initial part of the keystream.
+            In fact, such part has been found to be distinguishable from random
+            data (while it shouldn't) and also correlated to key.
+
+            The recommended value is 3072_ bytes. The default value is 0.
+
+    :Return: an `ARC4Cipher` object
+
+    .. _3072: http://eprint.iacr.org/2002/067.pdf
+    """
+    return ARC4Cipher(key, *args, **kwargs)
+
+
+# Size of a data block (in bytes)
+block_size = 1
+# Size of a key (in bytes)
+key_size = range(1, 256+1)