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bn
bn_mod.c
Go to the documentation of this file.
1
/* crypto/bn/bn_mod.c */
2
/* Includes code written by Lenka Fibikova <
[email protected]
>
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* for the OpenSSL project. */
4
/* ====================================================================
5
* Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
6
*
7
* Redistribution and use in source and binary forms, with or without
8
* modification, are permitted provided that the following conditions
9
* are met:
10
*
11
* 1. Redistributions of source code must retain the above copyright
12
* notice, this list of conditions and the following disclaimer.
13
*
14
* 2. Redistributions in binary form must reproduce the above copyright
15
* notice, this list of conditions and the following disclaimer in
16
* the documentation and/or other materials provided with the
17
* distribution.
18
*
19
* 3. All advertising materials mentioning features or use of this
20
* software must display the following acknowledgment:
21
* "This product includes software developed by the OpenSSL Project
22
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
23
*
24
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
25
* endorse or promote products derived from this software without
26
* prior written permission. For written permission, please contact
27
*
[email protected]
.
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*
29
* 5. Products derived from this software may not be called "OpenSSL"
30
* nor may "OpenSSL" appear in their names without prior written
31
* permission of the OpenSSL Project.
32
*
33
* 6. Redistributions of any form whatsoever must retain the following
34
* acknowledgment:
35
* "This product includes software developed by the OpenSSL Project
36
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
37
*
38
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
39
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
40
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
41
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
42
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
43
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
44
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
45
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
46
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
47
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
48
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
49
* OF THE POSSIBILITY OF SUCH DAMAGE.
50
* ====================================================================
51
*
52
* This product includes cryptographic software written by Eric Young
53
* (
[email protected]
). This product includes software written by Tim
54
* Hudson (
[email protected]
).
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*
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*/
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/* Copyright (C) 1995-1998 Eric Young (
[email protected]
)
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* All rights reserved.
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*
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* This package is an SSL implementation written
61
* by Eric Young (
[email protected]
).
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* The implementation was written so as to conform with Netscapes SSL.
63
*
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* This library is free for commercial and non-commercial use as long as
65
* the following conditions are aheared to. The following conditions
66
* apply to all code found in this distribution, be it the RC4, RSA,
67
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
68
* included with this distribution is covered by the same copyright terms
69
* except that the holder is Tim Hudson (
[email protected]
).
70
*
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* Copyright remains Eric Young's, and as such any Copyright notices in
72
* the code are not to be removed.
73
* If this package is used in a product, Eric Young should be given attribution
74
* as the author of the parts of the library used.
75
* This can be in the form of a textual message at program startup or
76
* in documentation (online or textual) provided with the package.
77
*
78
* Redistribution and use in source and binary forms, with or without
79
* modification, are permitted provided that the following conditions
80
* are met:
81
* 1. Redistributions of source code must retain the copyright
82
* notice, this list of conditions and the following disclaimer.
83
* 2. Redistributions in binary form must reproduce the above copyright
84
* notice, this list of conditions and the following disclaimer in the
85
* documentation and/or other materials provided with the distribution.
86
* 3. All advertising materials mentioning features or use of this software
87
* must display the following acknowledgement:
88
* "This product includes cryptographic software written by
89
* Eric Young (
[email protected]
)"
90
* The word 'cryptographic' can be left out if the rouines from the library
91
* being used are not cryptographic related :-).
92
* 4. If you include any Windows specific code (or a derivative thereof) from
93
* the apps directory (application code) you must include an acknowledgement:
94
* "This product includes software written by Tim Hudson (
[email protected]
)"
95
*
96
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
97
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
98
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
99
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
100
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
101
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
102
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
103
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
104
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
105
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
106
* SUCH DAMAGE.
107
*
108
* The licence and distribution terms for any publically available version or
109
* derivative of this code cannot be changed. i.e. this code cannot simply be
110
* copied and put under another distribution licence
111
* [including the GNU Public Licence.]
112
*/
113
114
#if defined( INC_ALL )
115
#include "
bn_lcl.h
"
116
#else
117
#include "
bn/bn_lcl.h
"
118
#endif
/* Compiler-specific includes */
119
120
#if 0
/* now just a #define */
121
int
BN_mod
(
BIGNUM
*rem,
const
BIGNUM
*m,
const
BIGNUM
*d,
BN_CTX
*ctx)
122
{
123
return
(
BN_div
(NULL,rem,m,d,ctx));
124
/* note that rem->neg == m->neg (unless the remainder is zero) */
125
}
126
#endif
127
128
129
int
BN_nnmod
(
BIGNUM
*r,
const
BIGNUM
*m,
const
BIGNUM
*d,
BN_CTX
*ctx)
130
{
131
/* like BN_mod, but returns non-negative remainder
132
* (i.e., 0 <= r < |d| always holds) */
133
134
if
(!(
BN_mod
(r,m,d,ctx)))
135
return
0;
136
if
(!r->
neg
)
137
return
1;
138
/* now -|d| < r < 0, so we have to set r := r + |d| */
139
return
(d->
neg
?
BN_sub
:
BN_add
)(r, r, d);
140
}
141
142
143
int
BN_mod_add
(
BIGNUM
*r,
const
BIGNUM
*a,
const
BIGNUM
*b,
const
BIGNUM
*m,
BN_CTX
*ctx)
144
{
145
if
(!
BN_add
(r, a, b))
return
0;
146
return
BN_nnmod
(r, r, m, ctx);
147
}
148
149
150
/* BN_mod_add variant that may be used if both a and b are non-negative
151
* and less than m */
152
int
BN_mod_add_quick
(
BIGNUM
*r,
const
BIGNUM
*a,
const
BIGNUM
*b,
const
BIGNUM
*m)
153
{
154
if
(!
BN_uadd
(r, a, b))
return
0;
155
if
(
BN_ucmp
(r, m) >= 0)
156
return
BN_usub
(r, r, m);
157
return
1;
158
}
159
160
161
int
BN_mod_sub
(
BIGNUM
*r,
const
BIGNUM
*a,
const
BIGNUM
*b,
const
BIGNUM
*m,
BN_CTX
*ctx)
162
{
163
if
(!
BN_sub
(r, a, b))
return
0;
164
return
BN_nnmod
(r, r, m, ctx);
165
}
166
167
168
/* BN_mod_sub variant that may be used if both a and b are non-negative
169
* and less than m */
170
int
BN_mod_sub_quick
(
BIGNUM
*r,
const
BIGNUM
*a,
const
BIGNUM
*b,
const
BIGNUM
*m)
171
{
172
if
(!
BN_sub
(r, a, b))
return
0;
173
if
(r->
neg
)
174
return
BN_add
(r, r, m);
175
return
1;
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}
177
178
179
/* slow but works */
180
int
BN_mod_mul
(
BIGNUM
*r,
const
BIGNUM
*a,
const
BIGNUM
*b,
const
BIGNUM
*m,
181
BN_CTX
*ctx)
182
{
183
BIGNUM
*t;
184
int
ret=0;
185
186
bn_check_top
(a);
187
bn_check_top
(b);
188
bn_check_top
(m);
189
190
BN_CTX_start
(ctx);
191
if
((t =
BN_CTX_get
(ctx)) == NULL)
goto
err;
192
if
(a == b)
193
{
if
(!
BN_sqr
(t,a,ctx))
goto
err; }
194
else
195
{
if
(!
BN_mul
(t,a,b,ctx))
goto
err; }
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if
(!
BN_nnmod
(r,t,m,ctx))
goto
err;
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bn_check_top
(r);
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ret=1;
199
err:
200
BN_CTX_end
(ctx);
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return
(ret);
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}
203
204
205
int
BN_mod_sqr
(
BIGNUM
*r,
const
BIGNUM
*a,
const
BIGNUM
*m,
BN_CTX
*ctx)
206
{
207
if
(!
BN_sqr
(r, a, ctx))
return
0;
208
/* r->neg == 0, thus we don't need BN_nnmod */
209
return
BN_mod
(r, r, m, ctx);
210
}
211
212
213
int
BN_mod_lshift1
(
BIGNUM
*r,
const
BIGNUM
*a,
const
BIGNUM
*m,
BN_CTX
*ctx)
214
{
215
if
(!
BN_lshift1
(r, a))
return
0;
216
bn_check_top
(r);
217
return
BN_nnmod
(r, r, m, ctx);
218
}
219
220
221
/* BN_mod_lshift1 variant that may be used if a is non-negative
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* and less than m */
223
int
BN_mod_lshift1_quick
(
BIGNUM
*r,
const
BIGNUM
*a,
const
BIGNUM
*m)
224
{
225
if
(!
BN_lshift1
(r, a))
return
0;
226
bn_check_top
(r);
227
if
(
BN_cmp
(r, m) >= 0)
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return
BN_sub
(r, r, m);
229
return
1;
230
}
231
232
233
int
BN_mod_lshift
(
BIGNUM
*r,
const
BIGNUM
*a,
int
n
,
const
BIGNUM
*m,
BN_CTX
*ctx)
234
{
235
BIGNUM
*abs_m = NULL;
236
int
ret;
237
238
if
(!
BN_nnmod
(r, a, m, ctx))
return
0;
239
240
if
(m->
neg
)
241
{
242
abs_m =
BN_dup
(m);
243
if
(abs_m == NULL)
return
0;
244
abs_m->
neg
= 0;
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}
246
247
ret =
BN_mod_lshift_quick
(r, r, n, (abs_m ? abs_m : m));
248
bn_check_top
(r);
249
250
if
(abs_m)
251
BN_free
(abs_m);
252
return
ret;
253
}
254
255
256
/* BN_mod_lshift variant that may be used if a is non-negative
257
* and less than m */
258
int
BN_mod_lshift_quick
(
BIGNUM
*r,
const
BIGNUM
*a,
int
n
,
const
BIGNUM
*m)
259
{
260
if
(r != a)
261
{
262
if
(
BN_copy
(r, a) == NULL)
return
0;
263
}
264
265
while
(n > 0)
266
{
267
int
max_shift;
268
269
/* 0 < r < m */
270
max_shift =
BN_num_bits
(m) -
BN_num_bits
(r);
271
/* max_shift >= 0 */
272
273
if
(max_shift < 0)
274
{
275
BNerr
(
BN_F_BN_MOD_LSHIFT_QUICK
,
BN_R_INPUT_NOT_REDUCED
);
276
return
0;
277
}
278
279
if
(max_shift > n)
280
max_shift =
n
;
281
282
if
(max_shift)
283
{
284
if
(!
BN_lshift
(r, r, max_shift))
return
0;
285
n -= max_shift;
286
}
287
else
288
{
289
if
(!
BN_lshift1
(r, r))
return
0;
290
--
n
;
291
}
292
293
/* BN_num_bits(r) <= BN_num_bits(m) */
294
295
if
(
BN_cmp
(r, m) >= 0)
296
{
297
if
(!
BN_sub
(r, r, m))
return
0;
298
}
299
}
300
bn_check_top
(r);
301
302
return
1;
303
}
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