Line data Source code
1 : /* mpi-mul.c - MPI functions
2 : * Copyright (C) 1994, 1996, 1998, 2001, 2002, 2003 Free Software Foundation, Inc.
3 : *
4 : * This file is part of Libgcrypt.
5 : *
6 : * Libgcrypt is free software; you can redistribute it and/or modify
7 : * it under the terms of the GNU Lesser General Public License as
8 : * published by the Free Software Foundation; either version 2.1 of
9 : * the License, or (at your option) any later version.
10 : *
11 : * Libgcrypt is distributed in the hope that it will be useful,
12 : * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 : * GNU Lesser General Public License for more details.
15 : *
16 : * You should have received a copy of the GNU Lesser General Public
17 : * License along with this program; if not, write to the Free Software
18 : * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
19 : *
20 : * Note: This code is heavily based on the GNU MP Library.
21 : * Actually it's the same code with only minor changes in the
22 : * way the data is stored; this is to support the abstraction
23 : * of an optional secure memory allocation which may be used
24 : * to avoid revealing of sensitive data due to paging etc.
25 : */
26 :
27 : #include <config.h>
28 : #include <stdio.h>
29 : #include <stdlib.h>
30 : #include "mpi-internal.h"
31 :
32 :
33 : void
34 0 : _gcry_mpi_mul_ui (gcry_mpi_t prod, gcry_mpi_t mult, unsigned long small_mult)
35 : {
36 : mpi_size_t size, prod_size;
37 : mpi_ptr_t prod_ptr;
38 : mpi_limb_t cy;
39 : int sign;
40 :
41 0 : size = mult->nlimbs;
42 0 : sign = mult->sign;
43 :
44 0 : if( !size || !small_mult ) {
45 0 : prod->nlimbs = 0;
46 0 : prod->sign = 0;
47 0 : return;
48 : }
49 :
50 0 : prod_size = size + 1;
51 0 : if( prod->alloced < prod_size )
52 0 : mpi_resize( prod, prod_size );
53 0 : prod_ptr = prod->d;
54 :
55 0 : cy = _gcry_mpih_mul_1( prod_ptr, mult->d, size, (mpi_limb_t)small_mult );
56 0 : if( cy )
57 0 : prod_ptr[size++] = cy;
58 0 : prod->nlimbs = size;
59 0 : prod->sign = sign;
60 : }
61 :
62 :
63 : void
64 0 : _gcry_mpi_mul_2exp (gcry_mpi_t w, gcry_mpi_t u, unsigned long cnt)
65 : {
66 : mpi_size_t usize, wsize, limb_cnt;
67 : mpi_ptr_t wp;
68 : mpi_limb_t wlimb;
69 : int usign, wsign;
70 :
71 0 : usize = u->nlimbs;
72 0 : usign = u->sign;
73 :
74 0 : if( !usize ) {
75 0 : w->nlimbs = 0;
76 0 : w->sign = 0;
77 0 : return;
78 : }
79 :
80 0 : limb_cnt = cnt / BITS_PER_MPI_LIMB;
81 0 : wsize = usize + limb_cnt + 1;
82 0 : if( w->alloced < wsize )
83 0 : mpi_resize(w, wsize );
84 0 : wp = w->d;
85 0 : wsize = usize + limb_cnt;
86 0 : wsign = usign;
87 :
88 0 : cnt %= BITS_PER_MPI_LIMB;
89 0 : if( cnt ) {
90 0 : wlimb = _gcry_mpih_lshift( wp + limb_cnt, u->d, usize, cnt );
91 0 : if( wlimb ) {
92 0 : wp[wsize] = wlimb;
93 0 : wsize++;
94 : }
95 : }
96 : else {
97 0 : MPN_COPY_DECR( wp + limb_cnt, u->d, usize );
98 : }
99 :
100 : /* Zero all whole limbs at low end. Do it here and not before calling
101 : * mpn_lshift, not to lose for U == W. */
102 0 : MPN_ZERO( wp, limb_cnt );
103 :
104 0 : w->nlimbs = wsize;
105 0 : w->sign = wsign;
106 : }
107 :
108 :
109 : void
110 0 : _gcry_mpi_mul (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v)
111 : {
112 : mpi_size_t usize, vsize, wsize;
113 : mpi_ptr_t up, vp, wp;
114 : mpi_limb_t cy;
115 : int usign, vsign, usecure, vsecure, sign_product;
116 0 : int assign_wp=0;
117 0 : mpi_ptr_t tmp_limb=NULL;
118 0 : unsigned int tmp_limb_nlimbs = 0;
119 :
120 0 : if( u->nlimbs < v->nlimbs ) { /* Swap U and V. */
121 0 : usize = v->nlimbs;
122 0 : usign = v->sign;
123 0 : usecure = mpi_is_secure(v);
124 0 : up = v->d;
125 0 : vsize = u->nlimbs;
126 0 : vsign = u->sign;
127 0 : vsecure = mpi_is_secure(u);
128 0 : vp = u->d;
129 : }
130 : else {
131 0 : usize = u->nlimbs;
132 0 : usign = u->sign;
133 0 : usecure = mpi_is_secure(u);
134 0 : up = u->d;
135 0 : vsize = v->nlimbs;
136 0 : vsign = v->sign;
137 0 : vsecure = mpi_is_secure(v);
138 0 : vp = v->d;
139 : }
140 0 : sign_product = usign ^ vsign;
141 0 : wp = w->d;
142 :
143 : /* Ensure W has space enough to store the result. */
144 0 : wsize = usize + vsize;
145 0 : if ( !mpi_is_secure (w) && (mpi_is_secure (u) || mpi_is_secure (v)) ) {
146 : /* w is not allocated in secure space but u or v is. To make sure
147 : * that no temporray results are stored in w, we temporary use
148 : * a newly allocated limb space for w */
149 0 : wp = mpi_alloc_limb_space( wsize, 1 );
150 0 : assign_wp = 2; /* mark it as 2 so that we can later copy it back to
151 : * mormal memory */
152 : }
153 0 : else if( w->alloced < wsize ) {
154 0 : if( wp == up || wp == vp ) {
155 0 : wp = mpi_alloc_limb_space( wsize, mpi_is_secure(w) );
156 0 : assign_wp = 1;
157 : }
158 : else {
159 0 : mpi_resize(w, wsize );
160 0 : wp = w->d;
161 : }
162 : }
163 : else { /* Make U and V not overlap with W. */
164 0 : if( wp == up ) {
165 : /* W and U are identical. Allocate temporary space for U. */
166 0 : tmp_limb_nlimbs = usize;
167 0 : up = tmp_limb = mpi_alloc_limb_space( usize, usecure );
168 : /* Is V identical too? Keep it identical with U. */
169 0 : if( wp == vp )
170 0 : vp = up;
171 : /* Copy to the temporary space. */
172 0 : MPN_COPY( up, wp, usize );
173 : }
174 0 : else if( wp == vp ) {
175 : /* W and V are identical. Allocate temporary space for V. */
176 0 : tmp_limb_nlimbs = vsize;
177 0 : vp = tmp_limb = mpi_alloc_limb_space( vsize, vsecure );
178 : /* Copy to the temporary space. */
179 0 : MPN_COPY( vp, wp, vsize );
180 : }
181 : }
182 :
183 0 : if( !vsize )
184 0 : wsize = 0;
185 : else {
186 0 : cy = _gcry_mpih_mul( wp, up, usize, vp, vsize );
187 0 : wsize -= cy? 0:1;
188 : }
189 :
190 0 : if( assign_wp ) {
191 0 : if (assign_wp == 2) {
192 : /* copy the temp wp from secure memory back to normal memory */
193 0 : mpi_ptr_t tmp_wp = mpi_alloc_limb_space (wsize, 0);
194 0 : MPN_COPY (tmp_wp, wp, wsize);
195 0 : _gcry_mpi_free_limb_space (wp, 0);
196 0 : wp = tmp_wp;
197 : }
198 0 : _gcry_mpi_assign_limb_space( w, wp, wsize );
199 : }
200 0 : w->nlimbs = wsize;
201 0 : w->sign = sign_product;
202 0 : if( tmp_limb )
203 0 : _gcry_mpi_free_limb_space (tmp_limb, tmp_limb_nlimbs);
204 0 : }
205 :
206 :
207 : void
208 0 : _gcry_mpi_mulm (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v, gcry_mpi_t m)
209 : {
210 0 : mpi_mul (w, u, v);
211 0 : _gcry_mpi_tdiv_r (w, w, m);
212 0 : }
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