146 lines
5.3 KiB
Python
146 lines
5.3 KiB
Python
# ===================================================================
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#
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# Copyright (c) 2014, Legrandin <helderijs@gmail.com>
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# All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or without
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# modification, are permitted provided that the following conditions
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# are met:
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#
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# 1. Redistributions of source code must retain the above copyright
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# notice, this list of conditions and the following disclaimer.
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# 2. Redistributions in binary form must reproduce the above copyright
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# notice, this list of conditions and the following disclaimer in
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# the documentation and/or other materials provided with the
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# distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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# COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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# CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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# ===================================================================
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from Cryptodome.Util._raw_api import (load_pycryptodome_raw_lib, c_size_t,
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create_string_buffer, get_raw_buffer,
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c_uint8_ptr, is_writeable_buffer)
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_raw_strxor = load_pycryptodome_raw_lib(
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"Cryptodome.Util._strxor",
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"""
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void strxor(const uint8_t *in1,
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const uint8_t *in2,
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uint8_t *out, size_t len);
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void strxor_c(const uint8_t *in,
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uint8_t c,
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uint8_t *out,
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size_t len);
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""")
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def strxor(term1, term2, output=None):
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"""From two byte strings of equal length,
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create a third one which is the byte-by-byte XOR of the two.
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Args:
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term1 (bytes/bytearray/memoryview):
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The first byte string to XOR.
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term2 (bytes/bytearray/memoryview):
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The second byte string to XOR.
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output (bytearray/memoryview):
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The location where the result will be written to.
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It must have the same length as ``term1`` and ``term2``.
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If ``None``, the result is returned.
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:Return:
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If ``output`` is ``None``, a new byte string with the result.
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Otherwise ``None``.
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.. note::
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``term1`` and ``term2`` must have the same length.
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"""
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if len(term1) != len(term2):
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raise ValueError("Only byte strings of equal length can be xored")
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if output is None:
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result = create_string_buffer(len(term1))
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else:
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# Note: output may overlap with either input
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result = output
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if not is_writeable_buffer(output):
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raise TypeError("output must be a bytearray or a writeable memoryview")
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if len(term1) != len(output):
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raise ValueError("output must have the same length as the input"
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" (%d bytes)" % len(term1))
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_raw_strxor.strxor(c_uint8_ptr(term1),
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c_uint8_ptr(term2),
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c_uint8_ptr(result),
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c_size_t(len(term1)))
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if output is None:
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return get_raw_buffer(result)
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else:
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return None
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def strxor_c(term, c, output=None):
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"""From a byte string, create a second one of equal length
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where each byte is XOR-red with the same value.
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Args:
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term(bytes/bytearray/memoryview):
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The byte string to XOR.
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c (int):
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Every byte in the string will be XOR-ed with this value.
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It must be between 0 and 255 (included).
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output (None or bytearray/memoryview):
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The location where the result will be written to.
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It must have the same length as ``term``.
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If ``None``, the result is returned.
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Return:
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If ``output`` is ``None``, a new ``bytes`` string with the result.
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Otherwise ``None``.
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"""
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if not 0 <= c < 256:
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raise ValueError("c must be in range(256)")
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if output is None:
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result = create_string_buffer(len(term))
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else:
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# Note: output may overlap with either input
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result = output
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if not is_writeable_buffer(output):
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raise TypeError("output must be a bytearray or a writeable memoryview")
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if len(term) != len(output):
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raise ValueError("output must have the same length as the input"
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" (%d bytes)" % len(term))
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_raw_strxor.strxor_c(c_uint8_ptr(term),
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c,
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c_uint8_ptr(result),
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c_size_t(len(term))
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)
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if output is None:
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return get_raw_buffer(result)
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else:
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return None
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def _strxor_direct(term1, term2, result):
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"""Very fast XOR - check conditions!"""
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_raw_strxor.strxor(term1, term2, result, c_size_t(len(term1)))
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