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
|
/*
* Copyright 1998-2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include "internal/cryptlib.h"
#include "bn_lcl.h"
int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx)
{
/*
* like BN_mod, but returns non-negative remainder (i.e., 0 <= r < |d|
* always holds)
*/
if (!(BN_mod(r, m, d, ctx)))
return 0;
if (!r->neg)
return 1;
/* now -|d| < r < 0, so we have to set r := r + |d| */
return (d->neg ? BN_sub : BN_add) (r, r, d);
}
int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
BN_CTX *ctx)
{
if (!BN_add(r, a, b))
return 0;
return BN_nnmod(r, r, m, ctx);
}
/*
* BN_mod_add variant that may be used if both a and b are non-negative and
* less than m
*/
int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
const BIGNUM *m)
{
if (!BN_uadd(r, a, b))
return 0;
if (BN_ucmp(r, m) >= 0)
return BN_usub(r, r, m);
return 1;
}
int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
BN_CTX *ctx)
{
if (!BN_sub(r, a, b))
return 0;
return BN_nnmod(r, r, m, ctx);
}
/*
* BN_mod_sub variant that may be used if both a and b are non-negative and
* less than m
*/
int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
const BIGNUM *m)
{
if (!BN_sub(r, a, b))
return 0;
if (r->neg)
return BN_add(r, r, m);
return 1;
}
/* slow but works */
int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m,
BN_CTX *ctx)
{
BIGNUM *t;
int ret = 0;
bn_check_top(a);
bn_check_top(b);
bn_check_top(m);
BN_CTX_start(ctx);
if ((t = BN_CTX_get(ctx)) == NULL)
goto err;
if (a == b) {
if (!BN_sqr(t, a, ctx))
goto err;
} else {
if (!BN_mul(t, a, b, ctx))
goto err;
}
if (!BN_nnmod(r, t, m, ctx))
goto err;
bn_check_top(r);
ret = 1;
err:
BN_CTX_end(ctx);
return (ret);
}
int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
{
if (!BN_sqr(r, a, ctx))
return 0;
/* r->neg == 0, thus we don't need BN_nnmod */
return BN_mod(r, r, m, ctx);
}
int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx)
{
if (!BN_lshift1(r, a))
return 0;
bn_check_top(r);
return BN_nnmod(r, r, m, ctx);
}
/*
* BN_mod_lshift1 variant that may be used if a is non-negative and less than
* m
*/
int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m)
{
if (!BN_lshift1(r, a))
return 0;
bn_check_top(r);
if (BN_cmp(r, m) >= 0)
return BN_sub(r, r, m);
return 1;
}
int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m,
BN_CTX *ctx)
{
BIGNUM *abs_m = NULL;
int ret;
if (!BN_nnmod(r, a, m, ctx))
return 0;
if (m->neg) {
abs_m = BN_dup(m);
if (abs_m == NULL)
return 0;
abs_m->neg = 0;
}
ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m));
bn_check_top(r);
BN_free(abs_m);
return ret;
}
/*
* BN_mod_lshift variant that may be used if a is non-negative and less than
* m
*/
int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m)
{
if (r != a) {
if (BN_copy(r, a) == NULL)
return 0;
}
while (n > 0) {
int max_shift;
/* 0 < r < m */
max_shift = BN_num_bits(m) - BN_num_bits(r);
/* max_shift >= 0 */
if (max_shift < 0) {
BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED);
return 0;
}
if (max_shift > n)
max_shift = n;
if (max_shift) {
if (!BN_lshift(r, r, max_shift))
return 0;
n -= max_shift;
} else {
if (!BN_lshift1(r, r))
return 0;
--n;
}
/* BN_num_bits(r) <= BN_num_bits(m) */
if (BN_cmp(r, m) >= 0) {
if (!BN_sub(r, r, m))
return 0;
}
}
bn_check_top(r);
return 1;
}
|
