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# ===================================================================
#
# Copyright (c) 2014, Legrandin <[email protected]>
# 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):
"""From two byte strings of equal length,
create a third one which is the byte-by-byte XOR of the two.
Args:
term1 (bytes/bytearray/memoryview):
The first byte string to XOR.
term2 (bytes/bytearray/memoryview):
The second byte string to XOR.
output (bytearray/memoryview):
The location where the result will be written to.
It must have the same length as ``term1`` and ``term2``.
If ``None``, the result is returned.
:Return:
If ``output`` is ``None``, a new byte string with the result.
Otherwise ``None``.
.. note::
``term1`` and ``term2`` must have the same length.
"""
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):
"""From a byte string, create a second one of equal length
where each byte is XOR-red with the same value.
Args:
term(bytes/bytearray/memoryview):
The byte string to XOR.
c (int):
Every byte in the string will be XOR-ed with this value.
It must be between 0 and 255 (included).
output (None or bytearray/memoryview):
The location where the result will be written to.
It must have the same length as ``term``.
If ``None``, the result is returned.
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)))
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