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d02b48c6 | 1 | /* crypto/bn/bn_shift.c */ |
58964a49 | 2 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) |
d02b48c6 RE |
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. | |
40720ce3 | 8 | * |
d02b48c6 RE |
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). | |
40720ce3 | 15 | * |
d02b48c6 RE |
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. | |
40720ce3 | 22 | * |
d02b48c6 RE |
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 :-). | |
40720ce3 | 37 | * 4. If you include any Windows specific code (or a derivative thereof) from |
d02b48c6 RE |
38 | * the apps directory (application code) you must include an acknowledgement: |
39 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
40720ce3 | 40 | * |
d02b48c6 RE |
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. | |
40720ce3 | 52 | * |
d02b48c6 RE |
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 | ||
020fc820 | 63 | int BN_lshift1(BIGNUM *r, const BIGNUM *a) |
40720ce3 MC |
64 | { |
65 | register BN_ULONG *ap, *rp, t, c; | |
66 | int i; | |
d02b48c6 | 67 | |
40720ce3 MC |
68 | bn_check_top(r); |
69 | bn_check_top(a); | |
18f62d4b | 70 | |
40720ce3 MC |
71 | if (r != a) { |
72 | r->neg = a->neg; | |
73 | if (bn_wexpand(r, a->top + 1) == NULL) | |
74 | return (0); | |
75 | r->top = a->top; | |
76 | } else { | |
77 | if (bn_wexpand(r, a->top + 1) == NULL) | |
78 | return (0); | |
79 | } | |
80 | ap = a->d; | |
81 | rp = r->d; | |
82 | c = 0; | |
83 | for (i = 0; i < a->top; i++) { | |
84 | t = *(ap++); | |
85 | *(rp++) = ((t << 1) | c) & BN_MASK2; | |
86 | c = (t & BN_TBIT) ? 1 : 0; | |
87 | } | |
88 | if (c) { | |
89 | *rp = 1; | |
90 | r->top++; | |
91 | } | |
92 | bn_check_top(r); | |
93 | return (1); | |
94 | } | |
d02b48c6 | 95 | |
020fc820 | 96 | int BN_rshift1(BIGNUM *r, const BIGNUM *a) |
40720ce3 MC |
97 | { |
98 | BN_ULONG *ap, *rp, t, c; | |
99 | int i; | |
d02b48c6 | 100 | |
40720ce3 MC |
101 | bn_check_top(r); |
102 | bn_check_top(a); | |
18f62d4b | 103 | |
40720ce3 MC |
104 | if (BN_is_zero(a)) { |
105 | BN_zero(r); | |
106 | return (1); | |
107 | } | |
108 | if (a != r) { | |
109 | if (bn_wexpand(r, a->top) == NULL) | |
110 | return (0); | |
111 | r->top = a->top; | |
112 | r->neg = a->neg; | |
113 | } | |
114 | ap = a->d; | |
115 | rp = r->d; | |
116 | c = 0; | |
117 | for (i = a->top - 1; i >= 0; i--) { | |
118 | t = ap[i]; | |
119 | rp[i] = ((t >> 1) & BN_MASK2) | c; | |
120 | c = (t & 1) ? BN_TBIT : 0; | |
121 | } | |
122 | bn_correct_top(r); | |
123 | bn_check_top(r); | |
124 | return (1); | |
125 | } | |
d02b48c6 | 126 | |
84c15db5 | 127 | int BN_lshift(BIGNUM *r, const BIGNUM *a, int n) |
40720ce3 MC |
128 | { |
129 | int i, nw, lb, rb; | |
130 | BN_ULONG *t, *f; | |
131 | BN_ULONG l; | |
d02b48c6 | 132 | |
40720ce3 MC |
133 | bn_check_top(r); |
134 | bn_check_top(a); | |
18f62d4b | 135 | |
40720ce3 MC |
136 | r->neg = a->neg; |
137 | nw = n / BN_BITS2; | |
138 | if (bn_wexpand(r, a->top + nw + 1) == NULL) | |
139 | return (0); | |
140 | lb = n % BN_BITS2; | |
141 | rb = BN_BITS2 - lb; | |
142 | f = a->d; | |
143 | t = r->d; | |
144 | t[a->top + nw] = 0; | |
145 | if (lb == 0) | |
146 | for (i = a->top - 1; i >= 0; i--) | |
147 | t[nw + i] = f[i]; | |
148 | else | |
149 | for (i = a->top - 1; i >= 0; i--) { | |
150 | l = f[i]; | |
151 | t[nw + i + 1] |= (l >> rb) & BN_MASK2; | |
152 | t[nw + i] = (l << lb) & BN_MASK2; | |
153 | } | |
154 | memset(t, 0, nw * sizeof(t[0])); | |
155 | /* | |
156 | * for (i=0; i<nw; i++) t[i]=0; | |
157 | */ | |
158 | r->top = a->top + nw + 1; | |
159 | bn_correct_top(r); | |
160 | bn_check_top(r); | |
161 | return (1); | |
162 | } | |
d02b48c6 | 163 | |
020fc820 | 164 | int BN_rshift(BIGNUM *r, const BIGNUM *a, int n) |
40720ce3 MC |
165 | { |
166 | int i, j, nw, lb, rb; | |
167 | BN_ULONG *t, *f; | |
168 | BN_ULONG l, tmp; | |
d02b48c6 | 169 | |
40720ce3 MC |
170 | bn_check_top(r); |
171 | bn_check_top(a); | |
18f62d4b | 172 | |
40720ce3 MC |
173 | nw = n / BN_BITS2; |
174 | rb = n % BN_BITS2; | |
175 | lb = BN_BITS2 - rb; | |
176 | if (nw >= a->top || a->top == 0) { | |
177 | BN_zero(r); | |
178 | return (1); | |
179 | } | |
180 | if (r != a) { | |
181 | r->neg = a->neg; | |
182 | if (bn_wexpand(r, a->top - nw + 1) == NULL) | |
183 | return (0); | |
184 | } else { | |
185 | if (n == 0) | |
186 | return 1; /* or the copying loop will go berserk */ | |
187 | } | |
d02b48c6 | 188 | |
40720ce3 MC |
189 | f = &(a->d[nw]); |
190 | t = r->d; | |
191 | j = a->top - nw; | |
192 | r->top = j; | |
d02b48c6 | 193 | |
40720ce3 MC |
194 | if (rb == 0) { |
195 | for (i = j; i != 0; i--) | |
196 | *(t++) = *(f++); | |
197 | } else { | |
198 | l = *(f++); | |
199 | for (i = j - 1; i != 0; i--) { | |
200 | tmp = (l >> rb) & BN_MASK2; | |
201 | l = *(f++); | |
202 | *(t++) = (tmp | (l << lb)) & BN_MASK2; | |
203 | } | |
204 | *(t++) = (l >> rb) & BN_MASK2; | |
205 | } | |
206 | bn_correct_top(r); | |
207 | bn_check_top(r); | |
208 | return (1); | |
209 | } |