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+# ===================================================================
+#
+# Copyright (c) 2014, Legrandin <helderijs@gmail.com>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+# notice, this list of conditions and the following disclaimer in
+# the documentation and/or other materials provided with the
+# distribution.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+# ===================================================================
+
+from Cryptodome.Util._raw_api import (load_pycryptodome_raw_lib, c_size_t,
+ create_string_buffer, get_raw_buffer,
+ c_uint8_ptr, is_writeable_buffer)
+
+_raw_strxor = load_pycryptodome_raw_lib("Cryptodome.Util._strxor",
+ """
+ void strxor(const uint8_t *in1,
+ const uint8_t *in2,
+ uint8_t *out, size_t len);
+ void strxor_c(const uint8_t *in,
+ uint8_t c,
+ uint8_t *out,
+ size_t len);
+ """)
+
+
+def strxor(term1, term2, output=None):
+ """XOR two byte strings.
+
+ Args:
+ term1 (bytes/bytearray/memoryview):
+ The first term of the XOR operation.
+ term2 (bytes/bytearray/memoryview):
+ The second term of the XOR operation.
+ output (bytearray/memoryview):
+ The location where the result must be written to.
+ If ``None``, the result is returned.
+ :Return:
+ If ``output`` is ``None``, a new ``bytes`` string with the result.
+ Otherwise ``None``.
+ """
+
+ if len(term1) != len(term2):
+ raise ValueError("Only byte strings of equal length can be xored")
+
+ if output is None:
+ result = create_string_buffer(len(term1))
+ else:
+ # Note: output may overlap with either input
+ result = output
+
+ if not is_writeable_buffer(output):
+ raise TypeError("output must be a bytearray or a writeable memoryview")
+
+ if len(term1) != len(output):
+ raise ValueError("output must have the same length as the input"
+ " (%d bytes)" % len(term1))
+
+ _raw_strxor.strxor(c_uint8_ptr(term1),
+ c_uint8_ptr(term2),
+ c_uint8_ptr(result),
+ c_size_t(len(term1)))
+
+ if output is None:
+ return get_raw_buffer(result)
+ else:
+ return None
+
+
+def strxor_c(term, c, output=None):
+ """XOR a byte string with a repeated sequence of characters.
+
+ Args:
+ term(bytes/bytearray/memoryview):
+ The first term of the XOR operation.
+ c (bytes):
+ The byte that makes up the second term of the XOR operation.
+ output (None or bytearray/memoryview):
+ If not ``None``, the location where the result is stored into.
+
+ Return:
+ If ``output`` is ``None``, a new ``bytes`` string with the result.
+ Otherwise ``None``.
+ """
+
+ if not 0 <= c < 256:
+ raise ValueError("c must be in range(256)")
+
+ if output is None:
+ result = create_string_buffer(len(term))
+ else:
+ # Note: output may overlap with either input
+ result = output
+
+ if not is_writeable_buffer(output):
+ raise TypeError("output must be a bytearray or a writeable memoryview")
+
+ if len(term) != len(output):
+ raise ValueError("output must have the same length as the input"
+ " (%d bytes)" % len(term))
+
+ _raw_strxor.strxor_c(c_uint8_ptr(term),
+ c,
+ c_uint8_ptr(result),
+ c_size_t(len(term))
+ )
+
+ if output is None:
+ return get_raw_buffer(result)
+ else:
+ return None
+
+
+def _strxor_direct(term1, term2, result):
+ """Very fast XOR - check conditions!"""
+ _raw_strxor.strxor(term1, term2, result, c_size_t(len(term1)))
+