3688eb75 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id$ |
4 | * |
5 | * Abstraction for prime groups |
6 | * |
7 | * (c) 2004 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <mLib/sub.h> |
33 | |
34 | #include "mpmont.h" |
35 | #include "pgen.h" |
36 | |
37 | #define ge mp * |
38 | #include "group.h" |
39 | #include "group-guts.h" |
40 | |
41 | /*----- Main code ---------------------------------------------------------*/ |
42 | |
43 | /* --- Group operations --- */ |
44 | |
45 | static void gdestroygroup(group *gg) { |
46 | gctx_bin *g = (gctx_bin *)gg; |
47 | mp_drop(g->gen); mp_drop(g->g.r); mp_drop(g->g.h); |
48 | gfreduce_destroy(&g->r); |
49 | DESTROY(g); |
50 | } |
51 | |
52 | static mp **gcreate(group *gg) |
53 | { mp **x = CREATE(mp *); *x = MP_COPY(*gg->i); return (x); } |
54 | |
55 | static void gcopy(group *gg, mp **d, mp **x) |
56 | { mp *t = MP_COPY(*x); MP_DROP(*d); *d = t; } |
57 | |
58 | static void gburn(group *gg, mp **x) { (*x)->f |= MP_BURN; } |
59 | |
60 | static void gdestroy(group *gg, mp **x) { MP_DROP(*x); DESTROY(x); } |
61 | |
62 | static int gsamep(group *gg, group *hh) { |
63 | gctx_bin *g = (gctx_bin *)gg, *h = (gctx_bin *)hh; |
64 | return (MP_EQ(g->r.p, h->r.p)); |
65 | } |
66 | |
67 | static int geq(group *gg, mp **x, mp **y) { return (MP_EQ(*x, *y)); } |
68 | |
69 | static const char *gcheck(group *gg, grand *gr) { |
70 | gctx_bin *g = (gctx_bin *)gg; int rc; mp *t, *tt; |
71 | if (!gf_irreduciblep(g->r.p)) return ("p is not irreducible"); |
72 | t = mp_mul(MP_NEW, g->g.r, g->g.h); t = mp_add(t, t, MP_ONE); |
73 | tt = mp_lsl(MP_NEW, MP_ONE, g->g.nbits); |
74 | rc = MP_EQ(t, tt); MP_DROP(t); MP_DROP(tt); |
75 | if (!rc) return ("not a subgroup"); |
76 | return (group_stdcheck(gg, gr)); |
77 | } |
78 | |
79 | static void gmul(group *gg, mp **d, mp **x, mp **y) { |
80 | gctx_bin *g = (gctx_bin *)gg; mp *r = gf_mul(*d, *x, *y); |
81 | *d = gfreduce_do(&g->r, r, r); |
82 | } |
83 | |
84 | static void gsqr(group *gg, mp **d, mp **x) { |
85 | gctx_bin *g = (gctx_bin *)gg; mp *r = gf_sqr(*d, *x); |
86 | *d = gfreduce_do(&g->r, r, r); |
87 | } |
88 | |
89 | static void ginv(group *gg, mp **d, mp **x) |
90 | { gctx_bin *g = (gctx_bin *)gg; *d = gf_modinv(*d, *x, g->r.p); } |
91 | |
92 | static void gexp(group *gg, mp **d, mp **x, mp *n) |
93 | { gctx_bin *g = (gctx_bin *)gg; *d = gfreduce_exp(&g->r, *d, *x, n); } |
94 | |
95 | static int gread(group *gg, mp **d, const mptext_ops *ops, void *p) { |
96 | mp *t; if ((t = mp_read(MP_NEW, 0, ops, p)) == 0) return (-1); |
97 | mp_drop(*d); *d = t; return (0); |
98 | } |
99 | |
100 | static int gwrite(group *gg, mp **x, const mptext_ops *ops, void *p) { |
101 | int rc = -1; |
102 | if (!ops->put("0x", 2, p) && !mp_write(*x, 16, ops, p)) rc = 0; |
103 | return (rc); |
104 | } |
105 | |
106 | static mp *gtoint(group *gg, mp *d, mp **x) { return MP_COPY(*x); } |
107 | |
108 | static int gfromint(group *gg, mp **d, mp *x) { *d = MP_COPY(x); return 0; } |
109 | |
110 | static int gtobuf(group *gg, buf *b, mp **x) |
111 | { int rc = buf_putmp(b, *x); return (rc); } |
112 | |
113 | static int gfrombuf(group *gg, buf *b, mp **d) { |
114 | gctx_bin *g = (gctx_bin *)gg; mp *x; |
115 | if ((x = buf_getmp(b)) == 0) return (-1); |
116 | MP_DROP(*d); *d = gfreduce_do(&g->r, x, x); |
117 | return (0); |
118 | } |
119 | |
120 | static int gtoraw(group *gg, buf *b, mp **x) { |
121 | gctx_bin * g = (gctx_bin *)gg; octet *q; |
122 | if ((q = buf_get(b, g->g.noctets)) == 0) return (-1); |
123 | mp_storeb(*x, q, g->g.noctets); return (0); |
124 | } |
125 | |
126 | static int gfromraw(group *gg, buf *b, mp **d) { |
127 | gctx_bin * g = (gctx_bin *)gg; mp *x; octet *q; |
128 | if ((q = buf_get(b, g->g.noctets)) == 0) return (-1); |
129 | x = mp_loadb(MP_NEW, q, g->g.noctets); |
130 | MP_DROP(*d); *d = gfreduce_do(&g->r, x, x); |
131 | return (0); |
132 | } |
133 | |
134 | /* --- @group_binary@ --- * |
135 | * |
136 | * Arguments: @const gbin_param *gb@ = group parameters |
137 | * |
138 | * Returns: A pointer to the group, or null. |
139 | * |
140 | * Use: Constructs an abstract group interface for a subgroup of a |
141 | * prime field. Group elements are @mp *@ pointers. |
142 | */ |
143 | |
144 | static const group_ops gops = { |
145 | GTY_BINARY, "bin", |
146 | gdestroygroup, gcreate, gcopy, gburn, gdestroy, |
147 | gsamep, geq, group_stdidentp, |
148 | gcheck, |
149 | gmul, gsqr, ginv, group_stddiv, gexp, group_stdmexp, |
150 | gread, gwrite, |
151 | gtoint, gfromint, group_stdtoec, group_stdfromec, gtobuf, gfrombuf, |
152 | gtoraw, gfromraw |
153 | }; |
154 | |
155 | group *group_binary(const gbin_param *gb) |
156 | { |
157 | gctx_bin *g; |
158 | mp *t; |
159 | |
160 | if (!MP_POSP(gb->p)) |
161 | return (0); |
162 | g = CREATE(gctx_bin); |
163 | g->g.ops = &gops; |
164 | g->g.nbits = mp_bits(gb->p) - 1; |
165 | g->g.noctets = (g->g.nbits + 7) >> 3; |
166 | gfreduce_create(&g->r, gb->p); |
167 | g->one = MP_ONE; |
168 | g->g.i = &g->one; |
169 | g->gen = MP_COPY(gb->g); |
170 | g->g.g = &g->gen; |
171 | g->g.r = MP_COPY(gb->q); |
172 | t = mp_lsl(MP_NEW, MP_ONE, g->g.nbits); |
173 | t = mp_sub(t, t, MP_ONE); |
174 | g->g.h = MP_NEW; mp_div(&g->g.h, 0, t, gb->q); |
175 | MP_DROP(t); |
176 | return (&g->g); |
177 | } |
178 | |
179 | /*----- That's all, folks -------------------------------------------------*/ |