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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: f-binpoly.c,v 1.9 2004/04/08 01:36:15 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 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <mLib/sub.h> |
33 | |
34 | #include "field.h" |
35 | #include "gf.h" |
36 | #include "gfreduce.h" |
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37 | #include "mprand.h" |
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38 | #include "gfn.h" |
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39 | |
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40 | /*----- Polynomial basis --------------------------------------------------*/ |
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41 | |
42 | typedef struct fctx { |
43 | field f; |
44 | gfreduce r; |
45 | } fctx; |
46 | |
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47 | /* --- Field operations --- */ |
48 | |
49 | static void fdestroy(field *ff) |
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50 | { fctx *f = (fctx *)ff; gfreduce_destroy(&f->r); DESTROY(f); } |
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51 | |
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52 | static mp *frand(field *f, mp *d, grand *r) |
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53 | { return (mprand(d, f->nbits, r, 0)); } |
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54 | |
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55 | static int fzerop(field *ff, mp *x) { return (!MP_LEN(x)); } |
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56 | |
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57 | static mp *fadd(field *ff, mp *d, mp *x, mp *y) { return (gf_add(d, x, y)); } |
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58 | |
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59 | static mp *fmul(field *ff, mp *d, mp *x, mp *y) { |
60 | fctx *f = (fctx *)ff; d = gf_mul(d, x, y); |
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61 | return (gfreduce_do(&f->r, d, d)); |
62 | } |
63 | |
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64 | static mp *fsqr(field *ff, mp *d, mp *x) { |
65 | fctx *f = (fctx *)ff; d = gf_sqr(d, x); |
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66 | return (gfreduce_do(&f->r, d, d)); |
67 | } |
68 | |
69 | static mp *finv(field *ff, mp *d, mp *x) |
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70 | { fctx *f = (fctx *)ff; d = gf_modinv(d, x, f->r.p); return (d); } |
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71 | |
72 | static mp *freduce(field *ff, mp *d, mp *x) |
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73 | { fctx *f = (fctx *)ff; return (gfreduce_do(&f->r, d, x)); } |
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74 | |
75 | static mp *fsqrt(field *ff, mp *d, mp *x) |
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76 | { fctx *f = (fctx *)ff; return (gfreduce_sqrt(&f->r, d, x)); } |
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77 | |
78 | static mp *fquadsolve(field *ff, mp *d, mp *x) |
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79 | { fctx *f = (fctx *)ff; return (gfreduce_quadsolve(&f->r, d, x)); } |
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80 | |
81 | /* --- Field operations table --- */ |
82 | |
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83 | static const field_ops fops = { |
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84 | FTY_BINARY, "binpoly", |
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85 | fdestroy, frand, field_stdsamep, |
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86 | freduce, field_id, |
87 | fzerop, field_id, fadd, fadd, fmul, fsqr, finv, freduce, fsqrt, |
88 | fquadsolve, |
89 | 0, 0, 0, 0 |
90 | }; |
91 | |
92 | /* --- @field_binpoly@ --- * |
93 | * |
94 | * Arguments: @mp *p@ = the reduction polynomial |
95 | * |
96 | * Returns: A pointer to the field. |
97 | * |
98 | * Use: Creates a field structure for a binary field mod @p@. |
99 | */ |
100 | |
101 | field *field_binpoly(mp *p) |
102 | { |
103 | fctx *f = CREATE(fctx); |
104 | f->f.ops = &fops; |
105 | f->f.zero = MP_ZERO; |
106 | f->f.one = MP_ONE; |
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107 | f->f.nbits = mp_bits(p) - 1; |
108 | f->f.noctets = (f->f.nbits + 7) >> 3; |
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109 | gfreduce_create(&f->r, p); |
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110 | f->f.m = f->r.p; |
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111 | return (&f->f); |
112 | } |
113 | |
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114 | /*----- Normal basis ------------------------------------------------------*/ |
115 | |
116 | typedef struct fnctx { |
117 | fctx f; |
118 | gfn ntop, pton; |
119 | } fnctx; |
120 | |
121 | /* --- Field operations --- */ |
122 | |
123 | static void fndestroy(field *ff) { |
124 | fnctx *f = (fnctx *)ff; gfreduce_destroy(&f->f.r); |
125 | gfn_destroy(&f->ntop); gfn_destroy(&f->pton); |
126 | DESTROY(f); |
127 | } |
128 | |
129 | static int fnsamep(field *ff, field *gg) { |
130 | fnctx *f = (fnctx *)ff, *g = (fnctx *)gg; |
131 | return (MP_EQ(f->ntop.r[0], g->ntop.r[0]) && field_stdsamep(ff, gg)); |
132 | } |
133 | |
134 | static mp *fnin(field *ff, mp *d, mp *x) |
135 | { fnctx *f = (fnctx *)ff; return (gfn_transform(&f->ntop, d, x)); } |
136 | |
137 | static mp *fnout(field *ff, mp *d, mp *x) |
138 | { fnctx *f = (fnctx *)ff; return (gfn_transform(&f->pton, d, x)); } |
139 | |
140 | /* --- Field operations table --- */ |
141 | |
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142 | static const field_ops fnops = { |
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143 | FTY_BINARY, "binnorm", |
144 | fndestroy, frand, fnsamep, |
145 | fnin, fnout, |
146 | fzerop, field_id, fadd, fadd, fmul, fsqr, finv, freduce, fsqrt, |
147 | fquadsolve, |
148 | 0, 0, 0, 0 |
149 | }; |
150 | |
151 | /* --- @field_binnorm@ --- * |
152 | * |
153 | * Arguments: @mp *p@ = the reduction polynomial |
154 | * @mp *beta@ = representation of normal point |
155 | * |
156 | * Returns: A pointer to the field. |
157 | * |
158 | * Use: Creates a field structure for a binary field mod @p@ which |
159 | * uses a normal basis representation externally. Computations |
160 | * are still done on a polynomial-basis representation. |
161 | */ |
162 | |
163 | field *field_binnorm(mp *p, mp *beta) |
164 | { |
165 | fnctx *f = CREATE(fnctx); |
166 | f->f.f.ops = &fnops; |
167 | f->f.f.zero = MP_ZERO; |
168 | f->f.f.one = MP_ONE; |
169 | f->f.f.nbits = mp_bits(p) - 1; |
170 | f->f.f.noctets = (f->f.f.nbits + 7) >> 3; |
171 | gfreduce_create(&f->f.r, p); |
172 | f->f.f.m = f->f.r.p; |
173 | gfn_create(p, beta, &f->ntop, &f->pton); |
174 | return (&f->f.f); |
175 | } |
176 | |
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177 | /*----- That's all, folks -------------------------------------------------*/ |