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d02b48c6 | 1 | /* crypto/bn/bn_word.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. | |
ae5c8664 | 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). | |
ae5c8664 | 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. | |
ae5c8664 | 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 :-). | |
ae5c8664 | 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)" | |
ae5c8664 | 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. | |
ae5c8664 | 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 | ||
7999c65c | 63 | BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w) |
ae5c8664 | 64 | { |
d02b48c6 | 65 | #ifndef BN_LLONG |
ae5c8664 | 66 | BN_ULONG ret = 0; |
d02b48c6 | 67 | #else |
ae5c8664 | 68 | BN_ULLONG ret = 0; |
d02b48c6 | 69 | #endif |
ae5c8664 | 70 | int i; |
d02b48c6 | 71 | |
ae5c8664 MC |
72 | if (w == 0) |
73 | return (BN_ULONG)-1; | |
0260405c | 74 | |
ae5c8664 MC |
75 | bn_check_top(a); |
76 | w &= BN_MASK2; | |
77 | for (i = a->top - 1; i >= 0; i--) { | |
d02b48c6 | 78 | #ifndef BN_LLONG |
ae5c8664 MC |
79 | ret = ((ret << BN_BITS4) | ((a->d[i] >> BN_BITS4) & BN_MASK2l)) % w; |
80 | ret = ((ret << BN_BITS4) | (a->d[i] & BN_MASK2l)) % w; | |
d02b48c6 | 81 | #else |
ae5c8664 MC |
82 | ret = (BN_ULLONG) (((ret << (BN_ULLONG) BN_BITS2) | a->d[i]) % |
83 | (BN_ULLONG) w); | |
d02b48c6 | 84 | #endif |
ae5c8664 MC |
85 | } |
86 | return ((BN_ULONG)ret); | |
87 | } | |
d02b48c6 | 88 | |
6b691a5c | 89 | BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w) |
ae5c8664 MC |
90 | { |
91 | BN_ULONG ret = 0; | |
92 | int i, j; | |
93 | ||
94 | bn_check_top(a); | |
95 | w &= BN_MASK2; | |
96 | ||
97 | if (!w) | |
98 | /* actually this an error (division by zero) */ | |
99 | return (BN_ULONG)-1; | |
100 | if (a->top == 0) | |
101 | return 0; | |
102 | ||
103 | /* normalize input (so bn_div_words doesn't complain) */ | |
104 | j = BN_BITS2 - BN_num_bits_word(w); | |
105 | w <<= j; | |
106 | if (!BN_lshift(a, a, j)) | |
107 | return (BN_ULONG)-1; | |
108 | ||
109 | for (i = a->top - 1; i >= 0; i--) { | |
110 | BN_ULONG l, d; | |
111 | ||
112 | l = a->d[i]; | |
113 | d = bn_div_words(ret, l, w); | |
114 | ret = (l - ((d * w) & BN_MASK2)) & BN_MASK2; | |
115 | a->d[i] = d; | |
116 | } | |
117 | if ((a->top > 0) && (a->d[a->top - 1] == 0)) | |
118 | a->top--; | |
119 | ret >>= j; | |
120 | bn_check_top(a); | |
121 | return (ret); | |
122 | } | |
d02b48c6 | 123 | |
6b691a5c | 124 | int BN_add_word(BIGNUM *a, BN_ULONG w) |
ae5c8664 MC |
125 | { |
126 | BN_ULONG l; | |
127 | int i; | |
128 | ||
129 | bn_check_top(a); | |
130 | w &= BN_MASK2; | |
131 | ||
132 | /* degenerate case: w is zero */ | |
133 | if (!w) | |
134 | return 1; | |
135 | /* degenerate case: a is zero */ | |
136 | if (BN_is_zero(a)) | |
137 | return BN_set_word(a, w); | |
138 | /* handle 'a' when negative */ | |
139 | if (a->neg) { | |
140 | a->neg = 0; | |
141 | i = BN_sub_word(a, w); | |
142 | if (!BN_is_zero(a)) | |
143 | a->neg = !(a->neg); | |
144 | return (i); | |
145 | } | |
146 | for (i = 0; w != 0 && i < a->top; i++) { | |
147 | a->d[i] = l = (a->d[i] + w) & BN_MASK2; | |
148 | w = (w > l) ? 1 : 0; | |
149 | } | |
150 | if (w && i == a->top) { | |
151 | if (bn_wexpand(a, a->top + 1) == NULL) | |
152 | return 0; | |
153 | a->top++; | |
154 | a->d[i] = w; | |
155 | } | |
156 | bn_check_top(a); | |
157 | return (1); | |
158 | } | |
d02b48c6 | 159 | |
6b691a5c | 160 | int BN_sub_word(BIGNUM *a, BN_ULONG w) |
ae5c8664 MC |
161 | { |
162 | int i; | |
163 | ||
164 | bn_check_top(a); | |
165 | w &= BN_MASK2; | |
166 | ||
167 | /* degenerate case: w is zero */ | |
168 | if (!w) | |
169 | return 1; | |
170 | /* degenerate case: a is zero */ | |
171 | if (BN_is_zero(a)) { | |
172 | i = BN_set_word(a, w); | |
173 | if (i != 0) | |
174 | BN_set_negative(a, 1); | |
175 | return i; | |
176 | } | |
177 | /* handle 'a' when negative */ | |
178 | if (a->neg) { | |
179 | a->neg = 0; | |
180 | i = BN_add_word(a, w); | |
181 | a->neg = 1; | |
182 | return (i); | |
183 | } | |
184 | ||
185 | if ((a->top == 1) && (a->d[0] < w)) { | |
186 | a->d[0] = w - a->d[0]; | |
187 | a->neg = 1; | |
188 | return (1); | |
189 | } | |
190 | i = 0; | |
191 | for (;;) { | |
192 | if (a->d[i] >= w) { | |
193 | a->d[i] -= w; | |
194 | break; | |
195 | } else { | |
196 | a->d[i] = (a->d[i] - w) & BN_MASK2; | |
197 | i++; | |
198 | w = 1; | |
199 | } | |
200 | } | |
201 | if ((a->d[i] == 0) && (i == (a->top - 1))) | |
202 | a->top--; | |
203 | bn_check_top(a); | |
204 | return (1); | |
205 | } | |
d02b48c6 | 206 | |
6b691a5c | 207 | int BN_mul_word(BIGNUM *a, BN_ULONG w) |
ae5c8664 MC |
208 | { |
209 | BN_ULONG ll; | |
210 | ||
211 | bn_check_top(a); | |
212 | w &= BN_MASK2; | |
213 | if (a->top) { | |
214 | if (w == 0) | |
215 | BN_zero(a); | |
216 | else { | |
217 | ll = bn_mul_words(a->d, a->d, a->top, w); | |
218 | if (ll) { | |
219 | if (bn_wexpand(a, a->top + 1) == NULL) | |
220 | return (0); | |
221 | a->d[a->top++] = ll; | |
222 | } | |
223 | } | |
224 | } | |
225 | bn_check_top(a); | |
226 | return (1); | |
227 | } |