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| # =================================================================== | |
| # | |
| # Copyright (c) 2018, Helder Eijs <[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 ._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): | |
| 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 | |