File size: 8,103 Bytes
ba2f5d6
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
#
#  SelfTest/Math/test_modexp.py: Self-test for module exponentiation
#
# ===================================================================
#
# Copyright (c) 2017, 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.
# ===================================================================

"""Self-test for the custom module exponentiation"""

import unittest

from Crypto.SelfTest.st_common import list_test_cases

from Crypto.Util.number import long_to_bytes, bytes_to_long

from Crypto.Util.py3compat import *

from Crypto.Util._raw_api import (load_pycryptodome_raw_lib,
                                  create_string_buffer,
                                  get_raw_buffer,
                                  c_size_t,
                                  c_ulonglong)

from Crypto.Hash import SHAKE128
from Crypto.Math.Numbers import Integer
from Crypto.Math._IntegerCustom import _raw_montgomery

from Crypto.Random.random import StrongRandom


def create_rng(tag):
    rng = StrongRandom(SHAKE128.new(data=tag))
    return rng

class ExceptionModulus(ValueError):
    pass

def monty_pow(base, exp, modulus):
    max_len = len(long_to_bytes(max(base, exp, modulus)))

    base_b, exp_b, modulus_b = [ long_to_bytes(x, max_len) for x in
                                 (base, exp, modulus) ]

    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(32)
                )

    if error == 17:
        raise ExceptionModulus()
    if error:
        raise ValueError("monty_pow failed with error: %d" % error)

    result = bytes_to_long(get_raw_buffer(out))
    return result

exponent1 = 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
modulus1 = 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


class TestModExp(unittest.TestCase):

    def test_small(self):
        self.assertEqual(1, monty_pow(11,12,19))

    def test_large_1(self):
        base = 0xfffffffffffffffffffffffffffffffffffffffffffffffffff
        expected = pow(base, exponent1, modulus1)
        result = monty_pow(base, exponent1, modulus1)
        self.assertEqual(result, expected)

    def test_zero_exp(self):
        base = 0xfffffffffffffffffffffffffffffffffffffffffffffffffff
        result = monty_pow(base, 0, modulus1)
        self.assertEqual(result, 1)

    def test_zero_base(self):
        result = monty_pow(0, exponent1, modulus1)
        self.assertEqual(result, 0)

    def test_zero_modulus(self):
        base = 0xfffffffffffffffffffffffffffffffffffffffffffffffff
        self.assertRaises(ExceptionModulus, monty_pow, base, exponent1, 0)
        self.assertRaises(ExceptionModulus, monty_pow, 0, 0, 0)

    def test_larger_exponent(self):
        base = modulus1 - 0xFFFFFFF
        expected = pow(base, modulus1<<64, modulus1)
        result = monty_pow(base, modulus1<<64, modulus1)
        self.assertEqual(result, expected)

    def test_even_modulus(self):
        base = modulus1 >> 4
        self.assertRaises(ExceptionModulus, monty_pow, base, exponent1, modulus1-1)

    def test_several_lengths(self):
        prng = SHAKE128.new().update(b('Test'))
        for length in range(1, 100):
            modulus2 = Integer.from_bytes(prng.read(length)) | 1
            base = Integer.from_bytes(prng.read(length)) % modulus2
            exponent2 = Integer.from_bytes(prng.read(length))

            expected = pow(base, exponent2, modulus2)
            result = monty_pow(base, exponent2, modulus2)
            self.assertEqual(result, expected)

    def test_variable_exponent(self):
        prng = create_rng(b('Test variable exponent'))
        for i in range(20):
            for j in range(7):
                modulus = prng.getrandbits(8*30) | 1
                base = prng.getrandbits(8*30) % modulus
                exponent = prng.getrandbits(i*8+j)

                expected = pow(base, exponent, modulus)
                result = monty_pow(base, exponent, modulus)
                self.assertEqual(result, expected)

                exponent ^= (1 << (i*8+j)) - 1

                expected = pow(base, exponent, modulus)
                result = monty_pow(base, exponent, modulus)
                self.assertEqual(result, expected)

    def test_stress_63(self):
        prng = create_rng(b('Test 63'))
        length = 63
        for _ in range(2000):
            modulus  = prng.getrandbits(8*length) | 1
            base     = prng.getrandbits(8*length) % modulus
            exponent = prng.getrandbits(8*length)

            expected = pow(base, exponent, modulus)
            result = monty_pow(base, exponent, modulus)
            self.assertEqual(result, expected)

    def test_stress_64(self):
        prng = create_rng(b('Test 64'))
        length = 64
        for _ in range(2000):
            modulus  = prng.getrandbits(8*length) | 1
            base     = prng.getrandbits(8*length) % modulus
            exponent = prng.getrandbits(8*length)

            expected = pow(base, exponent, modulus)
            result = monty_pow(base, exponent, modulus)
            self.assertEqual(result, expected)

    def test_stress_65(self):
        prng = create_rng(b('Test 65'))
        length = 65
        for _ in range(2000):
            modulus  = prng.getrandbits(8*length) | 1
            base     = prng.getrandbits(8*length) % modulus
            exponent = prng.getrandbits(8*length)

            expected = pow(base, exponent, modulus)
            result = monty_pow(base, exponent, modulus)
            self.assertEqual(result, expected)


def get_tests(config={}):
    tests = []
    tests += list_test_cases(TestModExp)
    return tests


if __name__ == '__main__':
    suite = lambda: unittest.TestSuite(get_tests())
    unittest.main(defaultTest='suite')