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