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1 | /* -*-c-*- |
2 | * |
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3 | * $Id$ |
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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 | |
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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" |
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39 | #include "group-guts.h" |
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40 | |
41 | /*----- Main code ---------------------------------------------------------*/ |
42 | |
43 | /* --- Group operations --- */ |
44 | |
45 | static void gdestroygroup(group *gg) { |
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46 | gctx_prime *g = (gctx_prime *)gg; |
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47 | mp_drop(g->gen); mp_drop(g->g.r); mp_drop(g->g.h); |
48 | mpmont_destroy(&g->mm); |
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 | |
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62 | static int gsamep(group *gg, group *hh) { |
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63 | gctx_prime *g = (gctx_prime *)gg, *h = (gctx_prime *)hh; |
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64 | return (MP_EQ(g->mm.m, h->mm.m)); |
65 | } |
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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) { |
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70 | gctx_prime *g = (gctx_prime *)gg; int rc; mp *t; |
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71 | if (!pgen_primep(g->mm.m, gr)) return ("p is not prime"); |
72 | t = mp_mul(MP_NEW, g->g.r, g->g.h); t = mp_add(t, t, MP_ONE); |
73 | rc = MP_EQ(t, g->mm.m); MP_DROP(t); if (!rc) return ("not a subgroup"); |
74 | return (group_stdcheck(gg, gr)); |
75 | } |
76 | |
77 | static void gmul(group *gg, mp **d, mp **x, mp **y) |
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78 | { gctx_prime *g = (gctx_prime *)gg; *d = mpmont_mul(&g->mm, *d, *x, *y); } |
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79 | |
80 | static void gsqr(group *gg, mp **d, mp **x) { |
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81 | gctx_prime *g = (gctx_prime *)gg; mp *r = mp_sqr(*d, *x); |
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82 | *d = mpmont_reduce(&g->mm, r, r); |
83 | } |
84 | |
85 | static void ginv(group *gg, mp **d, mp **x) { |
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86 | gctx_prime *g = (gctx_prime *)gg; mp *r = mpmont_reduce(&g->mm, *d, *x); |
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87 | r = mp_modinv(r, r, g->mm.m); *d = mpmont_mul(&g->mm, r, r, g->mm.r2); |
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88 | } |
89 | |
90 | static void gexp(group *gg, mp **d, mp **x, mp *n) |
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91 | { gctx_prime *g = (gctx_prime *)gg; *d = mpmont_expr(&g->mm, *d, *x, n); } |
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92 | |
93 | static void gmexp(group *gg, mp **d, const group_expfactor *f, size_t n) { |
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94 | gctx_prime *g = (gctx_prime *)gg; size_t i; |
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95 | mp_expfactor *ff = xmalloc(n * sizeof(mp_expfactor)); |
96 | for (i = 0; i < n; i++) { ff[i].base = *f[i].base; ff[i].exp = f[i].exp; } |
97 | *d = mpmont_mexpr(&g->mm, *d, ff, n); xfree(ff); |
98 | } |
99 | |
100 | static int gread(group *gg, mp **d, const mptext_ops *ops, void *p) { |
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101 | gctx_prime *g = (gctx_prime *)gg; mp *t; |
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102 | if ((t = mp_read(MP_NEW, 0, ops, p)) == 0) return (-1); |
103 | mp_drop(*d); *d = mpmont_mul(&g->mm, t, t, g->mm.r2); return (0); |
104 | } |
105 | |
106 | static int gwrite(group *gg, mp **x, const mptext_ops *ops, void *p) { |
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107 | gctx_prime *g = (gctx_prime *)gg; |
108 | mp *t = mpmont_reduce(&g->mm, MP_NEW, *x); |
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109 | int rc = mp_write(t, 10, ops, p); MP_DROP(t); return (rc); |
110 | } |
111 | |
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112 | static mp *gtoint(group *gg, mp *d, mp **x) { |
113 | gctx_prime *g = (gctx_prime *)gg; |
114 | return (mpmont_reduce(&g->mm, d, *x)); |
115 | } |
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116 | |
117 | static int gfromint(group *gg, mp **d, mp *x) { |
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118 | gctx_prime *g = (gctx_prime *)gg; mp_div(0, d, x, g->mm.m); |
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119 | *d = mpmont_mul(&g->mm, *d, *d, g->mm.r2); return (0); |
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120 | } |
121 | |
122 | static int gtobuf(group *gg, buf *b, mp **x) { |
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123 | gctx_prime *g = (gctx_prime *)gg; |
124 | mp *t = mpmont_reduce(&g->mm, MP_NEW, *x); |
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125 | int rc = buf_putmp(b, t); MP_DROP(t); return (rc); |
126 | } |
127 | |
128 | static int gfrombuf(group *gg, buf *b, mp **d) { |
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129 | gctx_prime * g = (gctx_prime *)gg; mp *x; |
130 | if ((x = buf_getmp(b)) == 0) return (-1); |
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131 | mp_div(0, &x, x, g->mm.m); mp_drop(*d); |
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132 | *d = mpmont_mul(&g->mm, x, x, g->mm.r2); return(0); |
133 | } |
134 | |
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135 | static int gtoraw(group *gg, buf *b, mp **x) { |
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136 | gctx_prime *g = (gctx_prime *)gg; octet *q; |
137 | mp *t = mpmont_reduce(&g->mm, MP_NEW, *x); |
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138 | if ((q = buf_get(b, g->g.noctets)) == 0) { MP_DROP(t); return (-1); } |
139 | mp_storeb(t, q, g->g.noctets); MP_DROP(t); return (0); |
140 | } |
141 | |
142 | static int gfromraw(group *gg, buf *b, mp **d) { |
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143 | gctx_prime * g = (gctx_prime *)gg; mp *x; octet *q; |
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144 | if ((q = buf_get(b, g->g.noctets)) == 0) return (-1); |
145 | x = mp_loadb(MP_NEW, q, g->g.noctets); |
146 | mp_div(0, &x, x, g->mm.m); mp_drop(*d); |
147 | *d = mpmont_mul(&g->mm, x, x, g->mm.r2); return(0); |
148 | } |
149 | |
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150 | /* --- @group_prime@ --- * |
151 | * |
152 | * Arguments: @const gprime_param *gp@ = group parameters |
153 | * |
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154 | * Returns: A pointer to the group, or null. |
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155 | * |
156 | * Use: Constructs an abstract group interface for a subgroup of a |
157 | * prime field. Group elements are @mp *@ pointers. |
158 | */ |
159 | |
160 | static const group_ops gops = { |
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161 | GTY_PRIME, "prime", |
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162 | gdestroygroup, gcreate, gcopy, gburn, gdestroy, |
163 | gsamep, geq, group_stdidentp, |
164 | gcheck, |
165 | gmul, gsqr, ginv, group_stddiv, gexp, gmexp, |
166 | gread, gwrite, |
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167 | gtoint, gfromint, group_stdtoec, group_stdfromec, gtobuf, gfrombuf, |
168 | gtoraw, gfromraw |
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169 | }; |
170 | |
171 | group *group_prime(const gprime_param *gp) |
172 | { |
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173 | gctx_prime *g; |
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174 | |
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175 | if (!MP_POSP(gp->p) || !MP_ODDP(gp->p)) |
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176 | return (0); |
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177 | g = CREATE(gctx_prime); |
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178 | g->g.ops = &gops; |
179 | g->g.nbits = mp_bits(gp->p); |
180 | g->g.noctets = (g->g.nbits + 7) >> 3; |
181 | mpmont_create(&g->mm, gp->p); |
182 | g->g.i = &g->mm.r; |
183 | g->gen = mpmont_mul(&g->mm, MP_NEW, gp->g, g->mm.r2); |
184 | g->g.g = &g->gen; |
185 | g->g.r = MP_COPY(gp->q); |
186 | g->g.h = MP_NEW; mp_div(&g->g.h, 0, gp->p, gp->q); |
187 | return (&g->g); |
188 | } |
189 | |
190 | /*----- That's all, folks -------------------------------------------------*/ |