Line data Source code
1 : /* crypto/bn/bn_shift.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 :
63 3420826 : int BN_lshift1(BIGNUM *r, const BIGNUM *a)
64 : {
65 : register BN_ULONG *ap, *rp, t, c;
66 : int i;
67 :
68 : bn_check_top(r);
69 : bn_check_top(a);
70 :
71 3420826 : if (r != a) {
72 1922520 : r->neg = a->neg;
73 1922520 : if (bn_wexpand(r, a->top + 1) == NULL)
74 : return (0);
75 1922520 : r->top = a->top;
76 : } else {
77 1498306 : if (bn_wexpand(r, a->top + 1) == NULL)
78 : return (0);
79 : }
80 3420826 : ap = a->d;
81 3420826 : rp = r->d;
82 : c = 0;
83 17104130 : for (i = 0; i < a->top; i++) {
84 13683304 : t = *(ap++);
85 13683304 : *(rp++) = ((t << 1) | c) & BN_MASK2;
86 13683304 : c = (t & BN_TBIT) ? 1 : 0;
87 : }
88 3420826 : if (c) {
89 2458351 : *rp = 1;
90 2458351 : r->top++;
91 : }
92 : bn_check_top(r);
93 : return (1);
94 : }
95 :
96 1729773 : int BN_rshift1(BIGNUM *r, const BIGNUM *a)
97 : {
98 : BN_ULONG *ap, *rp, t, c;
99 : int i, j;
100 :
101 : bn_check_top(r);
102 : bn_check_top(a);
103 :
104 1729773 : if (BN_is_zero(a)) {
105 3 : BN_zero(r);
106 3 : return (1);
107 : }
108 : i = a->top;
109 1729770 : ap = a->d;
110 1729770 : j = i - (ap[i - 1] == 1);
111 1729770 : if (a != r) {
112 126147 : if (bn_wexpand(r, j) == NULL)
113 : return (0);
114 126147 : r->neg = a->neg;
115 : }
116 1729770 : rp = r->d;
117 1729770 : t = ap[--i];
118 1729770 : c = (t & 1) ? BN_TBIT : 0;
119 1729770 : if (t >>= 1)
120 1216051 : rp[i] = t;
121 7303041 : while (i > 0) {
122 5573271 : t = ap[--i];
123 5573271 : rp[i] = ((t >> 1) & BN_MASK2) | c;
124 5573271 : c = (t & 1) ? BN_TBIT : 0;
125 : }
126 1729770 : r->top = j;
127 : bn_check_top(r);
128 1729770 : return (1);
129 : }
130 :
131 1494967 : int BN_lshift(BIGNUM *r, const BIGNUM *a, int n)
132 : {
133 : int i, nw, lb, rb;
134 : BN_ULONG *t, *f;
135 : BN_ULONG l;
136 :
137 : bn_check_top(r);
138 : bn_check_top(a);
139 :
140 1494967 : if (n < 0) {
141 0 : BNerr(BN_F_BN_LSHIFT, BN_R_INVALID_SHIFT);
142 0 : return 0;
143 : }
144 :
145 1494967 : r->neg = a->neg;
146 1494967 : nw = n / BN_BITS2;
147 1494967 : if (bn_wexpand(r, a->top + nw + 1) == NULL)
148 : return (0);
149 1494967 : lb = n % BN_BITS2;
150 1494967 : rb = BN_BITS2 - lb;
151 1494967 : f = a->d;
152 1494967 : t = r->d;
153 1494967 : t[a->top + nw] = 0;
154 1494967 : if (lb == 0)
155 273508 : for (i = a->top - 1; i >= 0; i--)
156 243560 : t[nw + i] = f[i];
157 : else
158 9127541 : for (i = a->top - 1; i >= 0; i--) {
159 7662522 : l = f[i];
160 7662522 : t[nw + i + 1] |= (l >> rb) & BN_MASK2;
161 7662522 : t[nw + i] = (l << lb) & BN_MASK2;
162 : }
163 1494967 : memset(t, 0, nw * sizeof(t[0]));
164 : /*
165 : * for (i=0; i<nw; i++) t[i]=0;
166 : */
167 1494967 : r->top = a->top + nw + 1;
168 1494967 : bn_correct_top(r);
169 : bn_check_top(r);
170 : return (1);
171 : }
172 :
173 1090307 : int BN_rshift(BIGNUM *r, const BIGNUM *a, int n)
174 : {
175 : int i, j, nw, lb, rb;
176 : BN_ULONG *t, *f;
177 : BN_ULONG l, tmp;
178 :
179 : bn_check_top(r);
180 : bn_check_top(a);
181 :
182 1090307 : if (n < 0) {
183 0 : BNerr(BN_F_BN_RSHIFT, BN_R_INVALID_SHIFT);
184 0 : return 0;
185 : }
186 :
187 1090307 : nw = n / BN_BITS2;
188 1090307 : rb = n % BN_BITS2;
189 1090307 : lb = BN_BITS2 - rb;
190 1090307 : if (nw >= a->top || a->top == 0) {
191 345 : BN_zero(r);
192 345 : return (1);
193 : }
194 1089962 : i = (BN_num_bits(a) - n + (BN_BITS2 - 1)) / BN_BITS2;
195 1089962 : if (r != a) {
196 218416 : r->neg = a->neg;
197 218416 : if (bn_wexpand(r, i) == NULL)
198 : return (0);
199 : } else {
200 871546 : if (n == 0)
201 : return 1; /* or the copying loop will go berserk */
202 : }
203 :
204 1089962 : f = &(a->d[nw]);
205 1089962 : t = r->d;
206 1089962 : j = a->top - nw;
207 1089962 : r->top = i;
208 :
209 1089962 : if (rb == 0) {
210 85506 : for (i = j; i != 0; i--)
211 85506 : *(t++) = *(f++);
212 : } else {
213 1078244 : l = *(f++);
214 3629610 : for (i = j - 1; i != 0; i--) {
215 2551366 : tmp = (l >> rb) & BN_MASK2;
216 2551366 : l = *(f++);
217 2551366 : *(t++) = (tmp | (l << lb)) & BN_MASK2;
218 : }
219 1078244 : if ((l = (l >> rb) & BN_MASK2))
220 1055573 : *(t) = l;
221 : }
222 : bn_check_top(r);
223 : return (1);
224 : }
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