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diff --git a/src/lib/libcrypto/bn/bn_recp.c b/src/lib/libcrypto/bn/bn_recp.c
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1/* crypto/bn/bn_recp.c */
2/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
3 * All rights reserved.
4 *
5 * This package is an SSL implementation written
6 * by Eric Young (eay@cryptsoft.com).
7 * The implementation was written so as to conform with Netscapes SSL.
8 *
9 * This library is free for commercial and non-commercial use as long as
10 * the following conditions are aheared to. The following conditions
11 * apply to all code found in this distribution, be it the RC4, RSA,
12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
13 * included with this distribution is covered by the same copyright terms
14 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
15 *
16 * Copyright remains Eric Young's, and as such any Copyright notices in
17 * the code are not to be removed.
18 * If this package is used in a product, Eric Young should be given attribution
19 * as the author of the parts of the library used.
20 * This can be in the form of a textual message at program startup or
21 * in documentation (online or textual) provided with the package.
22 *
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
25 * are met:
26 * 1. Redistributions of source code must retain the copyright
27 * notice, this list of conditions and the following disclaimer.
28 * 2. Redistributions in binary form must reproduce the above copyright
29 * notice, this list of conditions and the following disclaimer in the
30 * documentation and/or other materials provided with the distribution.
31 * 3. All advertising materials mentioning features or use of this software
32 * must display the following acknowledgement:
33 * "This product includes cryptographic software written by
34 * Eric Young (eay@cryptsoft.com)"
35 * The word 'cryptographic' can be left out if the rouines from the library
36 * being used are not cryptographic related :-).
37 * 4. If you include any Windows specific code (or a derivative thereof) from
38 * the apps directory (application code) you must include an acknowledgement:
39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
40 *
41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
51 * SUCH DAMAGE.
52 *
53 * The licence and distribution terms for any publically available version or
54 * derivative of this code cannot be changed. i.e. this code cannot simply be
55 * copied and put under another distribution licence
56 * [including the GNU Public Licence.]
57 */
58
59#include <stdio.h>
60#include "cryptlib.h"
61#include "bn_lcl.h"
62
63void BN_RECP_CTX_init(BN_RECP_CTX *recp)
64 {
65 BN_init(&(recp->N));
66 BN_init(&(recp->Nr));
67 recp->num_bits=0;
68 recp->flags=0;
69 }
70
71BN_RECP_CTX *BN_RECP_CTX_new(void)
72 {
73 BN_RECP_CTX *ret;
74
75 if ((ret=(BN_RECP_CTX *)OPENSSL_malloc(sizeof(BN_RECP_CTX))) == NULL)
76 return(NULL);
77
78 BN_RECP_CTX_init(ret);
79 ret->flags=BN_FLG_MALLOCED;
80 return(ret);
81 }
82
83void BN_RECP_CTX_free(BN_RECP_CTX *recp)
84 {
85 if(recp == NULL)
86 return;
87
88 BN_free(&(recp->N));
89 BN_free(&(recp->Nr));
90 if (recp->flags & BN_FLG_MALLOCED)
91 OPENSSL_free(recp);
92 }
93
94int BN_RECP_CTX_set(BN_RECP_CTX *recp, const BIGNUM *d, BN_CTX *ctx)
95 {
96 if (!BN_copy(&(recp->N),d)) return 0;
97 if (!BN_zero(&(recp->Nr))) return 0;
98 recp->num_bits=BN_num_bits(d);
99 recp->shift=0;
100 return(1);
101 }
102
103int BN_mod_mul_reciprocal(BIGNUM *r, const BIGNUM *x, const BIGNUM *y,
104 BN_RECP_CTX *recp, BN_CTX *ctx)
105 {
106 int ret=0;
107 BIGNUM *a;
108 const BIGNUM *ca;
109
110 BN_CTX_start(ctx);
111 if ((a = BN_CTX_get(ctx)) == NULL) goto err;
112 if (y != NULL)
113 {
114 if (x == y)
115 { if (!BN_sqr(a,x,ctx)) goto err; }
116 else
117 { if (!BN_mul(a,x,y,ctx)) goto err; }
118 ca = a;
119 }
120 else
121 ca=x; /* Just do the mod */
122
123 ret = BN_div_recp(NULL,r,ca,recp,ctx);
124err:
125 BN_CTX_end(ctx);
126 return(ret);
127 }
128
129int BN_div_recp(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m,
130 BN_RECP_CTX *recp, BN_CTX *ctx)
131 {
132 int i,j,ret=0;
133 BIGNUM *a,*b,*d,*r;
134
135 BN_CTX_start(ctx);
136 a=BN_CTX_get(ctx);
137 b=BN_CTX_get(ctx);
138 if (dv != NULL)
139 d=dv;
140 else
141 d=BN_CTX_get(ctx);
142 if (rem != NULL)
143 r=rem;
144 else
145 r=BN_CTX_get(ctx);
146 if (a == NULL || b == NULL || d == NULL || r == NULL) goto err;
147
148 if (BN_ucmp(m,&(recp->N)) < 0)
149 {
150 if (!BN_zero(d)) return 0;
151 if (!BN_copy(r,m)) return 0;
152 BN_CTX_end(ctx);
153 return(1);
154 }
155
156 /* We want the remainder
157 * Given input of ABCDEF / ab
158 * we need multiply ABCDEF by 3 digests of the reciprocal of ab
159 *
160 */
161
162 /* i := max(BN_num_bits(m), 2*BN_num_bits(N)) */
163 i=BN_num_bits(m);
164 j=recp->num_bits<<1;
165 if (j>i) i=j;
166
167 /* Nr := round(2^i / N) */
168 if (i != recp->shift)
169 recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
170 i,ctx); /* BN_reciprocal returns i, or -1 for an error */
171 if (recp->shift == -1) goto err;
172
173 /* d := |round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))|
174 * = |round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))|
175 * <= |(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)|
176 * = |m/N|
177 */
178 if (!BN_rshift(a,m,recp->num_bits)) goto err;
179 if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err;
180 if (!BN_rshift(d,b,i-recp->num_bits)) goto err;
181 d->neg=0;
182
183 if (!BN_mul(b,&(recp->N),d,ctx)) goto err;
184 if (!BN_usub(r,m,b)) goto err;
185 r->neg=0;
186
187#if 1
188 j=0;
189 while (BN_ucmp(r,&(recp->N)) >= 0)
190 {
191 if (j++ > 2)
192 {
193 BNerr(BN_F_BN_MOD_MUL_RECIPROCAL,BN_R_BAD_RECIPROCAL);
194 goto err;
195 }
196 if (!BN_usub(r,r,&(recp->N))) goto err;
197 if (!BN_add_word(d,1)) goto err;
198 }
199#endif
200
201 r->neg=BN_is_zero(r)?0:m->neg;
202 d->neg=m->neg^recp->N.neg;
203 ret=1;
204err:
205 BN_CTX_end(ctx);
206 return(ret);
207 }
208
209/* len is the expected size of the result
210 * We actually calculate with an extra word of precision, so
211 * we can do faster division if the remainder is not required.
212 */
213/* r := 2^len / m */
214int BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx)
215 {
216 int ret= -1;
217 BIGNUM t;
218
219 BN_init(&t);
220
221 if (!BN_zero(&t)) goto err;
222 if (!BN_set_bit(&t,len)) goto err;
223
224 if (!BN_div(r,NULL,&t,m,ctx)) goto err;
225
226 ret=len;
227err:
228 BN_free(&t);
229 return(ret);
230 }
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