1 /* mpi-add.c - MPI functions 1 /* mpi-add.c - MPI functions
2 * Copyright (C) 1994, 1996, 1998, 2001, 2002, 2 * Copyright (C) 1994, 1996, 1998, 2001, 2002,
3 * 2003 Free Software Foundation 3 * 2003 Free Software Foundation, Inc.
4 * 4 *
5 * This file is part of Libgcrypt. 5 * This file is part of Libgcrypt.
6 * 6 *
7 * Note: This code is heavily based on the GNU 7 * Note: This code is heavily based on the GNU MP Library.
8 * Actually it's the same code with only 8 * Actually it's the same code with only minor changes in the
9 * way the data is stored; this is to su 9 * way the data is stored; this is to support the abstraction
10 * of an optional secure memory allocati 10 * of an optional secure memory allocation which may be used
11 * to avoid revealing of sensitive data 11 * to avoid revealing of sensitive data due to paging etc.
12 */ 12 */
13 13
14 #include "mpi-internal.h" 14 #include "mpi-internal.h"
15 15
16 int mpi_add(MPI w, MPI u, MPI v) !! 16 /****************
>> 17 * Add the unsigned integer V to the mpi-integer U and store the
>> 18 * result in W. U and V may be the same.
>> 19 */
>> 20 void mpi_add_ui(MPI w, MPI u, unsigned long v)
>> 21 {
>> 22 mpi_ptr_t wp, up;
>> 23 mpi_size_t usize, wsize;
>> 24 int usign, wsign;
>> 25
>> 26 usize = u->nlimbs;
>> 27 usign = u->sign;
>> 28 wsign = 0;
>> 29
>> 30 /* If not space for W (and possible carry), increase space. */
>> 31 wsize = usize + 1;
>> 32 if (w->alloced < wsize)
>> 33 mpi_resize(w, wsize);
>> 34
>> 35 /* These must be after realloc (U may be the same as W). */
>> 36 up = u->d;
>> 37 wp = w->d;
>> 38
>> 39 if (!usize) { /* simple */
>> 40 wp[0] = v;
>> 41 wsize = v ? 1:0;
>> 42 } else if (!usign) { /* mpi is not negative */
>> 43 mpi_limb_t cy;
>> 44 cy = mpihelp_add_1(wp, up, usize, v);
>> 45 wp[usize] = cy;
>> 46 wsize = usize + cy;
>> 47 } else {
>> 48 /* The signs are different. Need exact comparison to determine
>> 49 * which operand to subtract from which.
>> 50 */
>> 51 if (usize == 1 && up[0] < v) {
>> 52 wp[0] = v - up[0];
>> 53 wsize = 1;
>> 54 } else {
>> 55 mpihelp_sub_1(wp, up, usize, v);
>> 56 /* Size can decrease with at most one limb. */
>> 57 wsize = usize - (wp[usize-1] == 0);
>> 58 wsign = 1;
>> 59 }
>> 60 }
>> 61
>> 62 w->nlimbs = wsize;
>> 63 w->sign = wsign;
>> 64 }
>> 65
>> 66
>> 67 void mpi_add(MPI w, MPI u, MPI v)
17 { 68 {
18 mpi_ptr_t wp, up, vp; 69 mpi_ptr_t wp, up, vp;
19 mpi_size_t usize, vsize, wsize; 70 mpi_size_t usize, vsize, wsize;
20 int usign, vsign, wsign; 71 int usign, vsign, wsign;
21 int err; <<
22 72
23 if (u->nlimbs < v->nlimbs) { /* Swap U 73 if (u->nlimbs < v->nlimbs) { /* Swap U and V. */
24 usize = v->nlimbs; 74 usize = v->nlimbs;
25 usign = v->sign; 75 usign = v->sign;
26 vsize = u->nlimbs; 76 vsize = u->nlimbs;
27 vsign = u->sign; 77 vsign = u->sign;
28 wsize = usize + 1; 78 wsize = usize + 1;
29 err = RESIZE_IF_NEEDED(w, wsiz !! 79 RESIZE_IF_NEEDED(w, wsize);
30 if (err) <<
31 return err; <<
32 /* These must be after realloc 80 /* These must be after realloc (u or v may be the same as w). */
33 up = v->d; 81 up = v->d;
34 vp = u->d; 82 vp = u->d;
35 } else { 83 } else {
36 usize = u->nlimbs; 84 usize = u->nlimbs;
37 usign = u->sign; 85 usign = u->sign;
38 vsize = v->nlimbs; 86 vsize = v->nlimbs;
39 vsign = v->sign; 87 vsign = v->sign;
40 wsize = usize + 1; 88 wsize = usize + 1;
41 err = RESIZE_IF_NEEDED(w, wsiz !! 89 RESIZE_IF_NEEDED(w, wsize);
42 if (err) <<
43 return err; <<
44 /* These must be after realloc 90 /* These must be after realloc (u or v may be the same as w). */
45 up = u->d; 91 up = u->d;
46 vp = v->d; 92 vp = v->d;
47 } 93 }
48 wp = w->d; 94 wp = w->d;
49 wsign = 0; 95 wsign = 0;
50 96
51 if (!vsize) { /* simple */ 97 if (!vsize) { /* simple */
52 MPN_COPY(wp, up, usize); 98 MPN_COPY(wp, up, usize);
53 wsize = usize; 99 wsize = usize;
54 wsign = usign; 100 wsign = usign;
55 } else if (usign != vsign) { /* differ 101 } else if (usign != vsign) { /* different sign */
56 /* This test is right since US 102 /* This test is right since USIZE >= VSIZE */
57 if (usize != vsize) { 103 if (usize != vsize) {
58 mpihelp_sub(wp, up, us 104 mpihelp_sub(wp, up, usize, vp, vsize);
59 wsize = usize; 105 wsize = usize;
60 MPN_NORMALIZE(wp, wsiz 106 MPN_NORMALIZE(wp, wsize);
61 wsign = usign; 107 wsign = usign;
62 } else if (mpihelp_cmp(up, vp, 108 } else if (mpihelp_cmp(up, vp, usize) < 0) {
63 mpihelp_sub_n(wp, vp, 109 mpihelp_sub_n(wp, vp, up, usize);
64 wsize = usize; 110 wsize = usize;
65 MPN_NORMALIZE(wp, wsiz 111 MPN_NORMALIZE(wp, wsize);
66 if (!usign) 112 if (!usign)
67 wsign = 1; 113 wsign = 1;
68 } else { 114 } else {
69 mpihelp_sub_n(wp, up, 115 mpihelp_sub_n(wp, up, vp, usize);
70 wsize = usize; 116 wsize = usize;
71 MPN_NORMALIZE(wp, wsiz 117 MPN_NORMALIZE(wp, wsize);
72 if (usign) 118 if (usign)
73 wsign = 1; 119 wsign = 1;
74 } 120 }
75 } else { /* U and V have same sign. Ad 121 } else { /* U and V have same sign. Add them. */
76 mpi_limb_t cy = mpihelp_add(wp 122 mpi_limb_t cy = mpihelp_add(wp, up, usize, vp, vsize);
77 wp[usize] = cy; 123 wp[usize] = cy;
78 wsize = usize + cy; 124 wsize = usize + cy;
79 if (usign) 125 if (usign)
80 wsign = 1; 126 wsign = 1;
81 } 127 }
82 128
83 w->nlimbs = wsize; 129 w->nlimbs = wsize;
84 w->sign = wsign; 130 w->sign = wsign;
85 return 0; <<
86 } 131 }
87 EXPORT_SYMBOL_GPL(mpi_add); 132 EXPORT_SYMBOL_GPL(mpi_add);
88 133
89 int mpi_sub(MPI w, MPI u, MPI v) !! 134 void mpi_sub(MPI w, MPI u, MPI v)
90 { 135 {
91 int err; !! 136 MPI vv = mpi_copy(v);
92 MPI vv; <<
93 <<
94 vv = mpi_copy(v); <<
95 if (!vv) <<
96 return -ENOMEM; <<
97 <<
98 vv->sign = !vv->sign; 137 vv->sign = !vv->sign;
99 err = mpi_add(w, u, vv); !! 138 mpi_add(w, u, vv);
100 mpi_free(vv); 139 mpi_free(vv);
101 <<
102 return err; <<
103 } 140 }
104 EXPORT_SYMBOL_GPL(mpi_sub); 141 EXPORT_SYMBOL_GPL(mpi_sub);
105 142
106 int mpi_addm(MPI w, MPI u, MPI v, MPI m) !! 143 void mpi_addm(MPI w, MPI u, MPI v, MPI m)
107 { 144 {
108 return mpi_add(w, u, v) ?: !! 145 mpi_add(w, u, v);
109 mpi_mod(w, w, m); !! 146 mpi_mod(w, w, m);
110 } 147 }
111 EXPORT_SYMBOL_GPL(mpi_addm); 148 EXPORT_SYMBOL_GPL(mpi_addm);
112 149
113 int mpi_subm(MPI w, MPI u, MPI v, MPI m) !! 150 void mpi_subm(MPI w, MPI u, MPI v, MPI m)
114 { 151 {
115 return mpi_sub(w, u, v) ?: !! 152 mpi_sub(w, u, v);
116 mpi_mod(w, w, m); !! 153 mpi_mod(w, w, m);
117 } 154 }
118 EXPORT_SYMBOL_GPL(mpi_subm); 155 EXPORT_SYMBOL_GPL(mpi_subm);
119 156
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