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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: f-binpoly.c,v 1.6 2004/04/01 12:50:09 mdw Exp $ |
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4 | * |
5 | * Binary fields with polynomial basis representation |
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 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: f-binpoly.c,v $ |
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33 | * Revision 1.6 2004/04/01 12:50:09 mdw |
34 | * Add cyclic group abstraction, with test code. Separate off exponentation |
35 | * functions for better static linking. Fix a buttload of bugs on the way. |
36 | * Generally ensure that negative exponents do inversion correctly. Add |
37 | * table of standard prime-field subgroups. (Binary field subgroups are |
38 | * currently unimplemented but easy to add if anyone ever finds a good one.) |
39 | * |
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40 | * Revision 1.5 2004/03/27 17:54:11 mdw |
41 | * Standard curves and curve checking. |
42 | * |
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43 | * Revision 1.4 2004/03/23 15:19:32 mdw |
44 | * Test elliptic curves more thoroughly. |
45 | * |
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46 | * Revision 1.3 2004/03/23 12:08:26 mdw |
47 | * Random field-element selection. |
48 | * |
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49 | * Revision 1.2 2004/03/21 22:52:06 mdw |
50 | * Merge and close elliptic curve branch. |
51 | * |
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52 | * Revision 1.1.2.1 2004/03/21 22:39:46 mdw |
53 | * Elliptic curves on binary fields work. |
54 | * |
55 | */ |
56 | |
57 | /*----- Header files ------------------------------------------------------*/ |
58 | |
59 | #include <mLib/sub.h> |
60 | |
61 | #include "field.h" |
62 | #include "gf.h" |
63 | #include "gfreduce.h" |
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64 | #include "mprand.h" |
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65 | |
66 | /*----- Data structures ---------------------------------------------------*/ |
67 | |
68 | typedef struct fctx { |
69 | field f; |
70 | gfreduce r; |
71 | } fctx; |
72 | |
73 | /*----- Main code ---------------------------------------------------------*/ |
74 | |
75 | /* --- Field operations --- */ |
76 | |
77 | static void fdestroy(field *ff) |
78 | { |
79 | fctx *f = (fctx *)ff; |
80 | gfreduce_destroy(&f->r); |
81 | DESTROY(f); |
82 | } |
83 | |
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84 | static mp *frand(field *f, mp *d, grand *r) |
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85 | { |
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86 | return (mprand(d, f->nbits, r, 0)); |
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87 | } |
88 | |
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89 | static int fzerop(field *ff, mp *x) |
90 | { |
91 | return (!MP_LEN(x)); |
92 | } |
93 | |
94 | static mp *fadd(field *ff, mp *d, mp *x, mp *y) |
95 | { |
96 | return (gf_add(d, x, y)); |
97 | } |
98 | |
99 | static mp *fmul(field *ff, mp *d, mp *x, mp *y) |
100 | { |
101 | fctx *f = (fctx *)ff; |
102 | d = gf_mul(d, x, y); |
103 | return (gfreduce_do(&f->r, d, d)); |
104 | } |
105 | |
106 | static mp *fsqr(field *ff, mp *d, mp *x) |
107 | { |
108 | fctx *f = (fctx *)ff; |
109 | d = gf_sqr(d, x); |
110 | return (gfreduce_do(&f->r, d, d)); |
111 | } |
112 | |
113 | static mp *finv(field *ff, mp *d, mp *x) |
114 | { |
115 | fctx *f = (fctx *)ff; |
116 | gf_gcd(0, 0, &d, f->r.p, x); |
117 | return (d); |
118 | } |
119 | |
120 | static mp *freduce(field *ff, mp *d, mp *x) |
121 | { |
122 | fctx *f = (fctx *)ff; |
123 | return (gfreduce_do(&f->r, d, x)); |
124 | } |
125 | |
126 | static mp *fsqrt(field *ff, mp *d, mp *x) |
127 | { |
128 | fctx *f = (fctx *)ff; |
129 | return (gfreduce_sqrt(&f->r, d, x)); |
130 | } |
131 | |
132 | static mp *fquadsolve(field *ff, mp *d, mp *x) |
133 | { |
134 | fctx *f = (fctx *)ff; |
135 | return (gfreduce_quadsolve(&f->r, d, x)); |
136 | } |
137 | |
138 | /* --- Field operations table --- */ |
139 | |
140 | static field_ops fops = { |
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141 | FTY_BINARY, "binpoly", |
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142 | fdestroy, frand, field_stdsamep, |
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143 | freduce, field_id, |
144 | fzerop, field_id, fadd, fadd, fmul, fsqr, finv, freduce, fsqrt, |
145 | fquadsolve, |
146 | 0, 0, 0, 0 |
147 | }; |
148 | |
149 | /* --- @field_binpoly@ --- * |
150 | * |
151 | * Arguments: @mp *p@ = the reduction polynomial |
152 | * |
153 | * Returns: A pointer to the field. |
154 | * |
155 | * Use: Creates a field structure for a binary field mod @p@. |
156 | */ |
157 | |
158 | field *field_binpoly(mp *p) |
159 | { |
160 | fctx *f = CREATE(fctx); |
161 | f->f.ops = &fops; |
162 | f->f.zero = MP_ZERO; |
163 | f->f.one = MP_ONE; |
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164 | f->f.nbits = mp_bits(p) - 1; |
165 | f->f.noctets = (f->f.nbits + 7) >> 3; |
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166 | gfreduce_create(&f->r, p); |
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167 | f->f.m = f->r.p; |
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168 | return (&f->f); |
169 | } |
170 | |
171 | /*----- That's all, folks -------------------------------------------------*/ |