1 /*
2 * Copyright 1995-2023 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
8 */
9
10 #include <stdio.h>
11 #include <stdlib.h>
12 #include <string.h>
13
14 #include "internal/nelem.h"
15
16 #include <openssl/bio.h>
17 #include <openssl/bn.h>
18 #include <openssl/rand.h>
19 #include <openssl/err.h>
20
21 #include "testutil.h"
22
23 #define NUM_BITS (BN_BITS2 * 4)
24
25 #define BN_print_var(v) test_output_bignum(#v, v)
26
27 /*
28 * Test that r == 0 in test_exp_mod_zero(). Returns one on success,
29 * returns zero and prints debug output otherwise.
30 */
a_is_zero_mod_one(const char * method,const BIGNUM * r,const BIGNUM * a)31 static int a_is_zero_mod_one(const char *method, const BIGNUM *r,
32 const BIGNUM *a)
33 {
34 if (!BN_is_zero(r)) {
35 TEST_error("%s failed: a ** 0 mod 1 = r (should be 0)", method);
36 BN_print_var(a);
37 BN_print_var(r);
38 return 0;
39 }
40 return 1;
41 }
42
43 /*
44 * test_mod_exp_zero tests that x**0 mod 1 == 0. It returns zero on success.
45 */
test_mod_exp_zero(void)46 static int test_mod_exp_zero(void)
47 {
48 BIGNUM *a = NULL, *p = NULL, *m = NULL;
49 BIGNUM *r = NULL;
50 BN_ULONG one_word = 1;
51 BN_CTX *ctx = BN_CTX_new();
52 int ret = 0, failed = 0;
53 BN_MONT_CTX *mont = NULL;
54
55 if (!TEST_ptr(m = BN_new())
56 || !TEST_ptr(a = BN_new())
57 || !TEST_ptr(p = BN_new())
58 || !TEST_ptr(r = BN_new()))
59 goto err;
60
61 BN_one(m);
62 BN_one(a);
63 BN_zero(p);
64
65 if (!TEST_true(BN_rand(a, 1024, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY)))
66 goto err;
67
68 if (!TEST_true(BN_mod_exp(r, a, p, m, ctx)))
69 goto err;
70
71 if (!TEST_true(a_is_zero_mod_one("BN_mod_exp", r, a)))
72 failed = 1;
73
74 if (!TEST_true(BN_mod_exp_recp(r, a, p, m, ctx)))
75 goto err;
76
77 if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_recp", r, a)))
78 failed = 1;
79
80 if (!TEST_true(BN_mod_exp_simple(r, a, p, m, ctx)))
81 goto err;
82
83 if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_simple", r, a)))
84 failed = 1;
85
86 if (!TEST_true(BN_mod_exp_mont(r, a, p, m, ctx, NULL)))
87 goto err;
88
89 if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_mont", r, a)))
90 failed = 1;
91
92 if (!TEST_true(BN_mod_exp_mont_consttime(r, a, p, m, ctx, NULL)))
93 goto err;
94
95 if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_mont_consttime", r, a)))
96 failed = 1;
97
98 if (!TEST_ptr(mont = BN_MONT_CTX_new()))
99 goto err;
100
101 ERR_set_mark();
102 /* mont is not set but passed in */
103 if (!TEST_false(BN_mod_exp_mont_consttime(r, p, a, m, ctx, mont)))
104 goto err;
105 if (!TEST_false(BN_mod_exp_mont(r, p, a, m, ctx, mont)))
106 goto err;
107 ERR_pop_to_mark();
108
109 if (!TEST_true(BN_MONT_CTX_set(mont, m, ctx)))
110 goto err;
111
112 /* we compute 0 ** a mod 1 here, to execute code that uses mont */
113 if (!TEST_true(BN_mod_exp_mont_consttime(r, p, a, m, ctx, mont)))
114 goto err;
115
116 if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_mont_consttime", r, a)))
117 failed = 1;
118
119 if (!TEST_true(BN_mod_exp_mont(r, p, a, m, ctx, mont)))
120 goto err;
121
122 if (!TEST_true(a_is_zero_mod_one("BN_mod_exp_mont", r, a)))
123 failed = 1;
124
125 /*
126 * A different codepath exists for single word multiplication
127 * in non-constant-time only.
128 */
129 if (!TEST_true(BN_mod_exp_mont_word(r, one_word, p, m, ctx, NULL)))
130 goto err;
131
132 if (!TEST_BN_eq_zero(r)) {
133 TEST_error("BN_mod_exp_mont_word failed: "
134 "1 ** 0 mod 1 = r (should be 0)");
135 BN_print_var(r);
136 goto err;
137 }
138
139 ret = !failed;
140 err:
141 BN_free(r);
142 BN_free(a);
143 BN_free(p);
144 BN_free(m);
145 BN_MONT_CTX_free(mont);
146 BN_CTX_free(ctx);
147
148 return ret;
149 }
150
test_mod_exp(int round)151 static int test_mod_exp(int round)
152 {
153 BN_CTX *ctx;
154 unsigned char c;
155 int ret = 0;
156 BIGNUM *r_mont = NULL;
157 BIGNUM *r_mont_const = NULL;
158 BIGNUM *r_recp = NULL;
159 BIGNUM *r_simple = NULL;
160 BIGNUM *a = NULL;
161 BIGNUM *b = NULL;
162 BIGNUM *m = NULL;
163
164 if (!TEST_ptr(ctx = BN_CTX_new()))
165 goto err;
166
167 if (!TEST_ptr(r_mont = BN_new())
168 || !TEST_ptr(r_mont_const = BN_new())
169 || !TEST_ptr(r_recp = BN_new())
170 || !TEST_ptr(r_simple = BN_new())
171 || !TEST_ptr(a = BN_new())
172 || !TEST_ptr(b = BN_new())
173 || !TEST_ptr(m = BN_new()))
174 goto err;
175
176 RAND_bytes(&c, 1);
177 c = (c % BN_BITS) - BN_BITS2;
178 BN_rand(a, NUM_BITS + c, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY);
179
180 RAND_bytes(&c, 1);
181 c = (c % BN_BITS) - BN_BITS2;
182 BN_rand(b, NUM_BITS + c, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ANY);
183
184 RAND_bytes(&c, 1);
185 c = (c % BN_BITS) - BN_BITS2;
186 BN_rand(m, NUM_BITS + c, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD);
187
188 if (!TEST_true(BN_mod(a, a, m, ctx))
189 || !TEST_true(BN_mod(b, b, m, ctx))
190 || !TEST_true(BN_mod_exp_mont(r_mont, a, b, m, ctx, NULL))
191 || !TEST_true(BN_mod_exp_recp(r_recp, a, b, m, ctx))
192 || !TEST_true(BN_mod_exp_simple(r_simple, a, b, m, ctx))
193 || !TEST_true(BN_mod_exp_mont_consttime(r_mont_const, a, b, m, ctx, NULL)))
194 goto err;
195
196 if (!TEST_BN_eq(r_simple, r_mont)
197 || !TEST_BN_eq(r_simple, r_recp)
198 || !TEST_BN_eq(r_simple, r_mont_const)) {
199 if (BN_cmp(r_simple, r_mont) != 0)
200 TEST_info("simple and mont results differ");
201 if (BN_cmp(r_simple, r_mont_const) != 0)
202 TEST_info("simple and mont const time results differ");
203 if (BN_cmp(r_simple, r_recp) != 0)
204 TEST_info("simple and recp results differ");
205
206 BN_print_var(a);
207 BN_print_var(b);
208 BN_print_var(m);
209 BN_print_var(r_simple);
210 BN_print_var(r_recp);
211 BN_print_var(r_mont);
212 BN_print_var(r_mont_const);
213 goto err;
214 }
215
216 ret = 1;
217 err:
218 BN_free(r_mont);
219 BN_free(r_mont_const);
220 BN_free(r_recp);
221 BN_free(r_simple);
222 BN_free(a);
223 BN_free(b);
224 BN_free(m);
225 BN_CTX_free(ctx);
226
227 return ret;
228 }
229
setup_tests(void)230 int setup_tests(void)
231 {
232 ADD_TEST(test_mod_exp_zero);
233 ADD_ALL_TESTS(test_mod_exp, 200);
234 return 1;
235 }
236