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 20136 : _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 20136 : size = mult->nlimbs;
42 20136 : sign = mult->sign;
43 :
44 20136 : if( !size || !small_mult ) {
45 0 : prod->nlimbs = 0;
46 0 : prod->sign = 0;
47 0 : return;
48 : }
49 :
50 20136 : prod_size = size + 1;
51 20136 : if( prod->alloced < prod_size )
52 0 : mpi_resize( prod, prod_size );
53 20136 : prod_ptr = prod->d;
54 :
55 20136 : cy = _gcry_mpih_mul_1( prod_ptr, mult->d, size, (mpi_limb_t)small_mult );
56 20136 : if( cy )
57 0 : prod_ptr[size++] = cy;
58 20136 : prod->nlimbs = size;
59 20136 : prod->sign = sign;
60 : }
61 :
62 :
63 : void
64 6874 : _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 6874 : usize = u->nlimbs;
72 6874 : usign = u->sign;
73 :
74 6874 : if( !usize ) {
75 0 : w->nlimbs = 0;
76 0 : w->sign = 0;
77 0 : return;
78 : }
79 :
80 6874 : limb_cnt = cnt / BITS_PER_MPI_LIMB;
81 6874 : wsize = usize + limb_cnt + 1;
82 6874 : if( w->alloced < wsize )
83 0 : mpi_resize(w, wsize );
84 6874 : wp = w->d;
85 6874 : wsize = usize + limb_cnt;
86 6874 : wsign = usign;
87 :
88 6874 : cnt %= BITS_PER_MPI_LIMB;
89 6874 : if( cnt ) {
90 6874 : wlimb = _gcry_mpih_lshift( wp + limb_cnt, u->d, usize, cnt );
91 6874 : 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 6874 : MPN_ZERO( wp, limb_cnt );
103 :
104 6874 : w->nlimbs = wsize;
105 6874 : w->sign = wsign;
106 : }
107 :
108 :
109 : void
110 28168613 : _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 28168613 : int assign_wp=0;
117 28168613 : mpi_ptr_t tmp_limb=NULL;
118 28168613 : unsigned int tmp_limb_nlimbs = 0;
119 :
120 28168613 : if( u->nlimbs < v->nlimbs ) { /* Swap U and V. */
121 106137 : usize = v->nlimbs;
122 106137 : usign = v->sign;
123 106137 : usecure = mpi_is_secure(v);
124 106137 : up = v->d;
125 106137 : vsize = u->nlimbs;
126 106137 : vsign = u->sign;
127 106137 : vsecure = mpi_is_secure(u);
128 106137 : vp = u->d;
129 : }
130 : else {
131 28062476 : usize = u->nlimbs;
132 28062476 : usign = u->sign;
133 28062476 : usecure = mpi_is_secure(u);
134 28062476 : up = u->d;
135 28062476 : vsize = v->nlimbs;
136 28062476 : vsign = v->sign;
137 28062476 : vsecure = mpi_is_secure(v);
138 28062476 : vp = v->d;
139 : }
140 28168613 : sign_product = usign ^ vsign;
141 28168613 : wp = w->d;
142 :
143 : /* Ensure W has space enough to store the result. */
144 28168613 : wsize = usize + vsize;
145 28168613 : 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 1155 : wp = mpi_alloc_limb_space( wsize, 1 );
150 1155 : assign_wp = 2; /* mark it as 2 so that we can later copy it back to
151 : * mormal memory */
152 : }
153 28167458 : else if( w->alloced < wsize ) {
154 49938 : if( wp == up || wp == vp ) {
155 16590 : wp = mpi_alloc_limb_space( wsize, mpi_is_secure(w) );
156 16590 : assign_wp = 1;
157 : }
158 : else {
159 33348 : mpi_resize(w, wsize );
160 33348 : wp = w->d;
161 : }
162 : }
163 : else { /* Make U and V not overlap with W. */
164 28117520 : if( wp == up ) {
165 : /* W and U are identical. Allocate temporary space for U. */
166 13020050 : tmp_limb_nlimbs = usize;
167 13020050 : up = tmp_limb = mpi_alloc_limb_space( usize, usecure );
168 : /* Is V identical too? Keep it identical with U. */
169 13020050 : if( wp == vp )
170 2297566 : vp = up;
171 : /* Copy to the temporary space. */
172 13020050 : MPN_COPY( up, wp, usize );
173 : }
174 15097470 : else if( wp == vp ) {
175 : /* W and V are identical. Allocate temporary space for V. */
176 536420 : tmp_limb_nlimbs = vsize;
177 536420 : vp = tmp_limb = mpi_alloc_limb_space( vsize, vsecure );
178 : /* Copy to the temporary space. */
179 536420 : MPN_COPY( vp, wp, vsize );
180 : }
181 : }
182 :
183 28168613 : if( !vsize )
184 35106 : wsize = 0;
185 : else {
186 28133507 : cy = _gcry_mpih_mul( wp, up, usize, vp, vsize );
187 28133507 : wsize -= cy? 0:1;
188 : }
189 :
190 28168613 : if( assign_wp ) {
191 17745 : if (assign_wp == 2) {
192 : /* copy the temp wp from secure memory back to normal memory */
193 1155 : mpi_ptr_t tmp_wp = mpi_alloc_limb_space (wsize, 0);
194 1155 : MPN_COPY (tmp_wp, wp, wsize);
195 1155 : _gcry_mpi_free_limb_space (wp, 0);
196 1155 : wp = tmp_wp;
197 : }
198 17745 : _gcry_mpi_assign_limb_space( w, wp, wsize );
199 : }
200 28168613 : w->nlimbs = wsize;
201 28168613 : w->sign = sign_product;
202 28168613 : if( tmp_limb )
203 13556470 : _gcry_mpi_free_limb_space (tmp_limb, tmp_limb_nlimbs);
204 28168613 : }
205 :
206 :
207 : void
208 96184 : _gcry_mpi_mulm (gcry_mpi_t w, gcry_mpi_t u, gcry_mpi_t v, gcry_mpi_t m)
209 : {
210 96184 : mpi_mul (w, u, v);
211 96184 : _gcry_mpi_tdiv_r (w, w, m);
212 96184 : }
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