73 lines
2.9 KiB
Python
73 lines
2.9 KiB
Python
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# ===================================================================
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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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"""
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Fast XOR of byte strings.
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"""
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from Crypto.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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expect_byte_string)
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_raw_strxor = load_pycryptodome_raw_lib("Crypto.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):
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"""Return term1 xored with term2.
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The two byte strings must have equal length."""
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expect_byte_string(term1)
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expect_byte_string(term2)
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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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result = create_string_buffer(len(term1))
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_raw_strxor.strxor(term1, term2, result, c_size_t(len(term1)))
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return get_raw_buffer(result)
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def strxor_c(term, c):
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"""Return term xored with a sequence of characters c."""
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expect_byte_string(term)
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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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result = create_string_buffer(len(term))
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_raw_strxor.strxor_c(term, c, result, c_size_t(len(term)))
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return get_raw_buffer(result)
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