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107 lines
3.8 KiB
Python
107 lines
3.8 KiB
Python
# ===================================================================
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#
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# Copyright (c) 2018, Helder Eijs <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 ._IntegerNative import IntegerNative
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from Crypto.Util.number import long_to_bytes, bytes_to_long
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from Crypto.Util._raw_api import (load_pycryptodome_raw_lib,
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create_string_buffer,
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get_raw_buffer, backend,
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c_size_t, c_ulonglong)
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from Crypto.Random.random import getrandbits
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c_defs = """
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int monty_pow(const uint8_t *base,
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const uint8_t *exp,
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const uint8_t *modulus,
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uint8_t *out,
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size_t len,
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uint64_t seed);
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"""
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_raw_montgomery = load_pycryptodome_raw_lib("Crypto.Math._modexp", c_defs)
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implementation = {"library": "custom", "api": backend}
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class IntegerCustom(IntegerNative):
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@staticmethod
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def from_bytes(byte_string):
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return IntegerCustom(bytes_to_long(byte_string))
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def inplace_pow(self, exponent, modulus=None):
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exp_value = int(exponent)
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if exp_value < 0:
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raise ValueError("Exponent must not be negative")
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# No modular reduction
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if modulus is None:
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self._value = pow(self._value, exp_value)
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return self
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# With modular reduction
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mod_value = int(modulus)
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if mod_value < 0:
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raise ValueError("Modulus must be positive")
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if mod_value == 0:
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raise ZeroDivisionError("Modulus cannot be zero")
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# C extension only works with odd moduli
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if (mod_value & 1) == 0:
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self._value = pow(self._value, exp_value, mod_value)
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return self
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max_len = len(long_to_bytes(max(self._value, exp_value, mod_value)))
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base_b = long_to_bytes(self._value, max_len)
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exp_b = long_to_bytes(exp_value, max_len)
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modulus_b = long_to_bytes(mod_value, max_len)
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out = create_string_buffer(max_len)
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error = _raw_montgomery.monty_pow(
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base_b,
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exp_b,
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modulus_b,
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out,
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c_size_t(max_len),
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c_ulonglong(getrandbits(64))
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)
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if error:
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raise ValueError("monty_pow failed with error: %d" % error)
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result = bytes_to_long(get_raw_buffer(out))
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self._value = result
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return self
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