File: mpi-mul.c

package info (click to toggle)
gnupg 1.4.18-7+deb8u5
  • links: PTS, VCS
  • area: main
  • in suites:
  • size: 34,476 kB
  • sloc: ansic: 127,074; sh: 7,535; asm: 4,610; makefile: 1,186; yacc: 291; perl: 196; pascal: 72; sed: 16
file content (214 lines) | stat: -rw-r--r-- 5,479 bytes parent folder | download | duplicates (10)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
/* mpi-mul.c  -  MPI functions
 *	Copyright (C) 1994, 1996 Free Software Foundation, Inc.
 *	Copyright (C) 1998, 2001 Free Software Foundation, Inc.
 *
 * This file is part of GnuPG.
 *
 * GnuPG is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 3 of the License, or
 * (at your option) any later version.
 *
 * GnuPG is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 *
 * Note: This code is heavily based on the GNU MP Library.
 *	 Actually it's the same code with only minor changes in the
 *	 way the data is stored; this is to support the abstraction
 *	 of an optional secure memory allocation which may be used
 *	 to avoid revealing of sensitive data due to paging etc.
 *	 The GNU MP Library itself is published under the LGPL;
 *	 however I decided to publish this code under the plain GPL.
 */

#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include "mpi-internal.h"


void
mpi_mul_ui( MPI prod, MPI mult, unsigned long small_mult )
{
    mpi_size_t size, prod_size;
    mpi_ptr_t  prod_ptr;
    mpi_limb_t cy;
    int sign;

    size = mult->nlimbs;
    sign = mult->sign;

    if( !size || !small_mult ) {
	prod->nlimbs = 0;
	prod->sign = 0;
	return;
    }

    prod_size = size + 1;
    if( prod->alloced < prod_size )
	mpi_resize( prod, prod_size );
    prod_ptr = prod->d;

    cy = mpihelp_mul_1( prod_ptr, mult->d, size, (mpi_limb_t)small_mult );
    if( cy )
	prod_ptr[size++] = cy;
    prod->nlimbs = size;
    prod->sign = sign;
}


void
mpi_mul_2exp( MPI w, MPI u, unsigned long cnt)
{
    mpi_size_t usize, wsize, limb_cnt;
    mpi_ptr_t wp;
    mpi_limb_t wlimb;
    int usign, wsign;

    usize = u->nlimbs;
    usign = u->sign;

    if( !usize ) {
	w->nlimbs = 0;
	w->sign = 0;
	return;
    }

    limb_cnt = cnt / BITS_PER_MPI_LIMB;
    wsize = usize + limb_cnt + 1;
    if( w->alloced < wsize )
	mpi_resize(w, wsize );
    wp = w->d;
    wsize = usize + limb_cnt;
    wsign = usign;

    cnt %= BITS_PER_MPI_LIMB;
    if( cnt ) {
	wlimb = mpihelp_lshift( wp + limb_cnt, u->d, usize, cnt );
	if( wlimb ) {
	    wp[wsize] = wlimb;
	    wsize++;
	}
    }
    else {
	MPN_COPY_DECR( wp + limb_cnt, u->d, usize );
    }

    /* Zero all whole limbs at low end.  Do it here and not before calling
     * mpn_lshift, not to lose for U == W.  */
    MPN_ZERO( wp, limb_cnt );

    w->nlimbs = wsize;
    w->sign = wsign;
}



void
mpi_mul( MPI w, MPI u, MPI v)
{
    mpi_size_t usize, vsize, wsize;
    mpi_ptr_t up, vp, wp;
    mpi_limb_t cy;
    int usign, vsign, usecure, vsecure, sign_product;
    int assign_wp=0;
    mpi_ptr_t tmp_limb=NULL;


    if( u->nlimbs < v->nlimbs ) { /* Swap U and V. */
	usize = v->nlimbs;
	usign = v->sign;
	usecure = mpi_is_secure(v);
	up    = v->d;
	vsize = u->nlimbs;
	vsign = u->sign;
	vsecure = mpi_is_secure(u);
	vp    = u->d;
    }
    else {
	usize = u->nlimbs;
	usign = u->sign;
	usecure = mpi_is_secure(u);
	up    = u->d;
	vsize = v->nlimbs;
	vsign = v->sign;
	vsecure = mpi_is_secure(v);
	vp    = v->d;
    }
    sign_product = usign ^ vsign;
    wp = w->d;

    /* Ensure W has space enough to store the result.  */
    wsize = usize + vsize;
    if ( !mpi_is_secure (w) && (mpi_is_secure (u) || mpi_is_secure (v)) ) {
        /* w is not allocated in secure space but u or v is.  To make sure
         * that no temporray results are stored in w, we temporary use 
         * a newly allocated limb space for w */
        wp = mpi_alloc_limb_space( wsize, 1 );
        assign_wp = 2; /* mark it as 2 so that we can later copy it back to
                        * mormal memory */
    }
    else if( w->alloced < wsize ) {
	if( wp == up || wp == vp ) {
	    wp = mpi_alloc_limb_space( wsize, mpi_is_secure(w) );
	    assign_wp = 1;
	}
	else {
	    mpi_resize(w, wsize );
	    wp = w->d;
	}
    }
    else { /* Make U and V not overlap with W.	*/
	if( wp == up ) {
	    /* W and U are identical.  Allocate temporary space for U.	*/
	    up = tmp_limb = mpi_alloc_limb_space( usize, usecure  );
	    /* Is V identical too?  Keep it identical with U.  */
	    if( wp == vp )
		vp = up;
	    /* Copy to the temporary space.  */
	    MPN_COPY( up, wp, usize );
	}
	else if( wp == vp ) {
	    /* W and V are identical.  Allocate temporary space for V.	*/
	    vp = tmp_limb = mpi_alloc_limb_space( vsize, vsecure );
	    /* Copy to the temporary space.  */
	    MPN_COPY( vp, wp, vsize );
	}
    }

    if( !vsize )
	wsize = 0;
    else {
	cy = mpihelp_mul( wp, up, usize, vp, vsize );
	wsize -= cy? 0:1;
    }

    if( assign_wp ) {
        if (assign_wp == 2) {
            /* copy the temp wp from secure memory back to normal memory */
	    mpi_ptr_t tmp_wp = mpi_alloc_limb_space (wsize, 0);
	    MPN_COPY (tmp_wp, wp, wsize);
            mpi_free_limb_space (wp);
            wp = tmp_wp;
        }
	mpi_assign_limb_space( w, wp, wsize );
    }
    w->nlimbs = wsize;
    w->sign = sign_product;
    if( tmp_limb )
	mpi_free_limb_space( tmp_limb );
}


void
mpi_mulm( MPI w, MPI u, MPI v, MPI m)
{
    mpi_mul(w, u, v);
    mpi_fdiv_r( w, w, m );
}