34e4f738 |
1 | /* -*-c-*- |
2 | * |
34e4f738 |
3 | * Abstraction for prime groups |
4 | * |
5 | * (c) 2004 Straylight/Edgeware |
6 | */ |
7 | |
45c0fd36 |
8 | /*----- Licensing notice --------------------------------------------------* |
34e4f738 |
9 | * |
10 | * This file is part of Catacomb. |
11 | * |
12 | * Catacomb is free software; you can redistribute it and/or modify |
13 | * it under the terms of the GNU Library General Public License as |
14 | * published by the Free Software Foundation; either version 2 of the |
15 | * License, or (at your option) any later version. |
45c0fd36 |
16 | * |
34e4f738 |
17 | * Catacomb is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU Library General Public License for more details. |
45c0fd36 |
21 | * |
34e4f738 |
22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with Catacomb; if not, write to the Free |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
25 | * MA 02111-1307, USA. |
26 | */ |
27 | |
34e4f738 |
28 | /*----- Header files ------------------------------------------------------*/ |
29 | |
30 | #include <mLib/sub.h> |
31 | |
32 | #include "mpmont.h" |
33 | #include "pgen.h" |
34 | |
35 | #define ge mp * |
f94b972d |
36 | #include "group-guts.h" |
34e4f738 |
37 | |
38 | /*----- Main code ---------------------------------------------------------*/ |
39 | |
40 | /* --- Group operations --- */ |
41 | |
42 | static void gdestroygroup(group *gg) { |
f94b972d |
43 | gctx_prime *g = (gctx_prime *)gg; |
34e4f738 |
44 | mp_drop(g->gen); mp_drop(g->g.r); mp_drop(g->g.h); |
45 | mpmont_destroy(&g->mm); |
46 | DESTROY(g); |
47 | } |
48 | |
49 | static mp **gcreate(group *gg) |
50 | { mp **x = CREATE(mp *); *x = MP_COPY(*gg->i); return (x); } |
51 | |
52 | static void gcopy(group *gg, mp **d, mp **x) |
53 | { mp *t = MP_COPY(*x); MP_DROP(*d); *d = t; } |
54 | |
55 | static void gburn(group *gg, mp **x) { (*x)->f |= MP_BURN; } |
56 | |
57 | static void gdestroy(group *gg, mp **x) { MP_DROP(*x); DESTROY(x); } |
58 | |
02d7884d |
59 | static int gsamep(group *gg, group *hh) { |
f94b972d |
60 | gctx_prime *g = (gctx_prime *)gg, *h = (gctx_prime *)hh; |
02d7884d |
61 | return (MP_EQ(g->mm.m, h->mm.m)); |
62 | } |
34e4f738 |
63 | |
64 | static int geq(group *gg, mp **x, mp **y) { return (MP_EQ(*x, *y)); } |
65 | |
66 | static const char *gcheck(group *gg, grand *gr) { |
f94b972d |
67 | gctx_prime *g = (gctx_prime *)gg; int rc; mp *t; |
34e4f738 |
68 | if (!pgen_primep(g->mm.m, gr)) return ("p is not prime"); |
69 | t = mp_mul(MP_NEW, g->g.r, g->g.h); t = mp_add(t, t, MP_ONE); |
70 | rc = MP_EQ(t, g->mm.m); MP_DROP(t); if (!rc) return ("not a subgroup"); |
71 | return (group_stdcheck(gg, gr)); |
72 | } |
73 | |
74 | static void gmul(group *gg, mp **d, mp **x, mp **y) |
f94b972d |
75 | { gctx_prime *g = (gctx_prime *)gg; *d = mpmont_mul(&g->mm, *d, *x, *y); } |
34e4f738 |
76 | |
77 | static void gsqr(group *gg, mp **d, mp **x) { |
f94b972d |
78 | gctx_prime *g = (gctx_prime *)gg; mp *r = mp_sqr(*d, *x); |
34e4f738 |
79 | *d = mpmont_reduce(&g->mm, r, r); |
80 | } |
81 | |
82 | static void ginv(group *gg, mp **d, mp **x) { |
f94b972d |
83 | gctx_prime *g = (gctx_prime *)gg; mp *r = mpmont_reduce(&g->mm, *d, *x); |
b817bfc6 |
84 | r = mp_modinv(r, r, g->mm.m); *d = mpmont_mul(&g->mm, r, r, g->mm.r2); |
34e4f738 |
85 | } |
86 | |
87 | static void gexp(group *gg, mp **d, mp **x, mp *n) |
f94b972d |
88 | { gctx_prime *g = (gctx_prime *)gg; *d = mpmont_expr(&g->mm, *d, *x, n); } |
34e4f738 |
89 | |
90 | static void gmexp(group *gg, mp **d, const group_expfactor *f, size_t n) { |
f94b972d |
91 | gctx_prime *g = (gctx_prime *)gg; size_t i; |
34e4f738 |
92 | mp_expfactor *ff = xmalloc(n * sizeof(mp_expfactor)); |
93 | for (i = 0; i < n; i++) { ff[i].base = *f[i].base; ff[i].exp = f[i].exp; } |
94 | *d = mpmont_mexpr(&g->mm, *d, ff, n); xfree(ff); |
95 | } |
96 | |
97 | static int gread(group *gg, mp **d, const mptext_ops *ops, void *p) { |
f94b972d |
98 | gctx_prime *g = (gctx_prime *)gg; mp *t; |
34e4f738 |
99 | if ((t = mp_read(MP_NEW, 0, ops, p)) == 0) return (-1); |
100 | mp_drop(*d); *d = mpmont_mul(&g->mm, t, t, g->mm.r2); return (0); |
101 | } |
102 | |
103 | static int gwrite(group *gg, mp **x, const mptext_ops *ops, void *p) { |
f94b972d |
104 | gctx_prime *g = (gctx_prime *)gg; |
105 | mp *t = mpmont_reduce(&g->mm, MP_NEW, *x); |
34e4f738 |
106 | int rc = mp_write(t, 10, ops, p); MP_DROP(t); return (rc); |
107 | } |
108 | |
f94b972d |
109 | static mp *gtoint(group *gg, mp *d, mp **x) { |
110 | gctx_prime *g = (gctx_prime *)gg; |
111 | return (mpmont_reduce(&g->mm, d, *x)); |
112 | } |
34e4f738 |
113 | |
114 | static int gfromint(group *gg, mp **d, mp *x) { |
f94b972d |
115 | gctx_prime *g = (gctx_prime *)gg; mp_div(0, d, x, g->mm.m); |
b817bfc6 |
116 | *d = mpmont_mul(&g->mm, *d, *d, g->mm.r2); return (0); |
34e4f738 |
117 | } |
118 | |
119 | static int gtobuf(group *gg, buf *b, mp **x) { |
f94b972d |
120 | gctx_prime *g = (gctx_prime *)gg; |
121 | mp *t = mpmont_reduce(&g->mm, MP_NEW, *x); |
34e4f738 |
122 | int rc = buf_putmp(b, t); MP_DROP(t); return (rc); |
123 | } |
124 | |
125 | static int gfrombuf(group *gg, buf *b, mp **d) { |
f94b972d |
126 | gctx_prime * g = (gctx_prime *)gg; mp *x; |
127 | if ((x = buf_getmp(b)) == 0) return (-1); |
02d7884d |
128 | mp_div(0, &x, x, g->mm.m); mp_drop(*d); |
34e4f738 |
129 | *d = mpmont_mul(&g->mm, x, x, g->mm.r2); return(0); |
130 | } |
131 | |
0f3faccd |
132 | static int gtoraw(group *gg, buf *b, mp **x) { |
f94b972d |
133 | gctx_prime *g = (gctx_prime *)gg; octet *q; |
134 | mp *t = mpmont_reduce(&g->mm, MP_NEW, *x); |
0f3faccd |
135 | if ((q = buf_get(b, g->g.noctets)) == 0) { MP_DROP(t); return (-1); } |
136 | mp_storeb(t, q, g->g.noctets); MP_DROP(t); return (0); |
137 | } |
138 | |
139 | static int gfromraw(group *gg, buf *b, mp **d) { |
f94b972d |
140 | gctx_prime * g = (gctx_prime *)gg; mp *x; octet *q; |
0f3faccd |
141 | if ((q = buf_get(b, g->g.noctets)) == 0) return (-1); |
142 | x = mp_loadb(MP_NEW, q, g->g.noctets); |
143 | mp_div(0, &x, x, g->mm.m); mp_drop(*d); |
144 | *d = mpmont_mul(&g->mm, x, x, g->mm.r2); return(0); |
145 | } |
146 | |
34e4f738 |
147 | /* --- @group_prime@ --- * |
148 | * |
149 | * Arguments: @const gprime_param *gp@ = group parameters |
150 | * |
02d7884d |
151 | * Returns: A pointer to the group, or null. |
34e4f738 |
152 | * |
153 | * Use: Constructs an abstract group interface for a subgroup of a |
154 | * prime field. Group elements are @mp *@ pointers. |
155 | */ |
156 | |
157 | static const group_ops gops = { |
f94b972d |
158 | GTY_PRIME, "prime", |
34e4f738 |
159 | gdestroygroup, gcreate, gcopy, gburn, gdestroy, |
160 | gsamep, geq, group_stdidentp, |
161 | gcheck, |
162 | gmul, gsqr, ginv, group_stddiv, gexp, gmexp, |
163 | gread, gwrite, |
0f3faccd |
164 | gtoint, gfromint, group_stdtoec, group_stdfromec, gtobuf, gfrombuf, |
165 | gtoraw, gfromraw |
34e4f738 |
166 | }; |
167 | |
168 | group *group_prime(const gprime_param *gp) |
169 | { |
f94b972d |
170 | gctx_prime *g; |
34e4f738 |
171 | |
a69a3efd |
172 | if (!MP_POSP(gp->p) || !MP_ODDP(gp->p)) |
02d7884d |
173 | return (0); |
f94b972d |
174 | g = CREATE(gctx_prime); |
34e4f738 |
175 | g->g.ops = &gops; |
176 | g->g.nbits = mp_bits(gp->p); |
177 | g->g.noctets = (g->g.nbits + 7) >> 3; |
178 | mpmont_create(&g->mm, gp->p); |
179 | g->g.i = &g->mm.r; |
180 | g->gen = mpmont_mul(&g->mm, MP_NEW, gp->g, g->mm.r2); |
181 | g->g.g = &g->gen; |
182 | g->g.r = MP_COPY(gp->q); |
183 | g->g.h = MP_NEW; mp_div(&g->g.h, 0, gp->p, gp->q); |
184 | return (&g->g); |
185 | } |
186 | |
187 | /*----- That's all, folks -------------------------------------------------*/ |