Commit | Line | Data |
---|---|---|
1c42b462 | 1 | /* -*-c-*- |
2 | * | |
b817bfc6 | 3 | * $Id: pgen-safe.c,v 1.5 2004/04/08 01:36:15 mdw Exp $ |
1c42b462 | 4 | * |
5 | * Safe prime generation | |
6 | * | |
7 | * (c) 1999 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 | ||
1c42b462 | 30 | /*----- Header files ------------------------------------------------------*/ |
31 | ||
32 | #include "mp.h" | |
33 | #include "mprand.h" | |
34 | #include "pgen.h" | |
35 | ||
36 | /*----- Main code ---------------------------------------------------------*/ | |
37 | ||
38 | /* --- @pgen_safestep@ --- * | |
39 | * | |
40 | * Steps two numbers, %$q$% and %$p = 2q + 1$%, such that neither has any | |
41 | * small factors. %$p$% is put in the event block. | |
42 | */ | |
43 | ||
44 | int pgen_safestep(int rq, pgen_event *ev, void *p) | |
45 | { | |
46 | pgen_safestepctx *c = p; | |
052b36d0 | 47 | int rc = PGEN_ABORT, qrc = 0; |
1c42b462 | 48 | |
49 | switch (rq) { | |
052b36d0 | 50 | |
51 | /* --- Set up the contexts --- */ | |
52 | ||
1c42b462 | 53 | case PGEN_BEGIN: { |
54 | mp *p = mp_split(MP_COPY(ev->m)); | |
55 | mp *q; | |
56 | p->v[0] |= 3; | |
57 | q = mp_lsr(MP_NEW, p, 1); | |
052b36d0 | 58 | rc = pfilt_create(&c->p, p); |
1c42b462 | 59 | qrc = pfilt_create(&c->q, q); |
052b36d0 | 60 | mp_drop(p); mp_drop(q); |
61 | } break; | |
62 | ||
63 | /* --- Step along --- */ | |
64 | ||
1c42b462 | 65 | case PGEN_TRY: |
1c42b462 | 66 | mp_drop(ev->m); |
052b36d0 | 67 | rc = pfilt_step(&c->p, 4); |
68 | qrc = pfilt_step(&c->q, 2); | |
69 | break; | |
70 | ||
1c42b462 | 71 | break; |
052b36d0 | 72 | |
73 | /* --- Tidy the toys away --- */ | |
74 | ||
1c42b462 | 75 | case PGEN_DONE: |
76 | pfilt_destroy(&c->q); | |
77 | pfilt_destroy(&c->p); | |
052b36d0 | 78 | return (PGEN_DONE); |
79 | } | |
80 | ||
81 | /* --- Continue stepping if necessary --- */ | |
82 | ||
83 | while (rc == PGEN_FAIL || qrc == PGEN_FAIL) { | |
84 | rc = pfilt_step(&c->p, 4); | |
85 | qrc = pfilt_step(&c->q, 2); | |
86 | } | |
87 | ||
88 | ev->m = MP_COPY(c->p.m); | |
89 | if (qrc == PGEN_TRY) | |
90 | rc = PGEN_TRY; | |
91 | return (rc); | |
92 | } | |
93 | ||
94 | /* --- @pgen_safejump@ --- * | |
95 | * | |
96 | * Jumps two numbers, %$q$% and %$p = 2q + 1$% such that neither has any | |
97 | * small factors. | |
98 | */ | |
99 | ||
100 | int pgen_safejump(int rq, pgen_event *ev, void *p) | |
101 | { | |
102 | pgen_safejumpctx *j = p; | |
103 | int rc = PGEN_ABORT, qrc = 0; | |
104 | ||
105 | switch (rq) { | |
106 | ||
107 | /* --- Set up the jump contexts --- * | |
108 | * | |
109 | * The jump in @j.q@ is congruent to 2 (mod 4); see @strongprime_setup@. | |
110 | * If @p@ is initially 1 (mod 4) then add @j.q@. Then double @j.q@ to | |
8b021c3f | 111 | * ensure that the step is 0 (mod 4). Ensure that @jq@ and @q@ don't |
112 | * have any common factors. | |
052b36d0 | 113 | */ |
114 | ||
115 | case PGEN_BEGIN: { | |
116 | mp *p = ev->m; | |
117 | mp *q; | |
8b021c3f | 118 | mp *g = MP_NEW; |
052b36d0 | 119 | if ((p->v[0] & 3) != 3) |
120 | p = mp_add(p, p, j->jq.m); | |
8b021c3f | 121 | q = mp_lsr(MP_NEW, p, 1); |
32fec2a2 | 122 | mp_gcd(&g, 0, 0, p, j->jq.m); |
8b021c3f | 123 | if (MP_CMP(g, >, MP_ONE)) { |
124 | ev->m = p; | |
125 | mp_drop(q); | |
126 | mp_drop(g); | |
127 | return (PGEN_ABORT); | |
128 | } | |
129 | mp_drop(g); | |
052b36d0 | 130 | rc = pfilt_create(&j->p, p); |
131 | pfilt_muladd(&j->jp, &j->jq, 2, 0); | |
052b36d0 | 132 | qrc = pfilt_create(&j->q, q); |
133 | mp_drop(p); | |
134 | mp_drop(q); | |
135 | } break; | |
136 | ||
137 | /* --- Step on one place --- */ | |
138 | ||
139 | case PGEN_TRY: | |
140 | mp_drop(ev->m); | |
141 | rc = pfilt_jump(&j->p, &j->jp); | |
142 | qrc = pfilt_jump(&j->q, &j->jq); | |
1c42b462 | 143 | break; |
052b36d0 | 144 | |
145 | /* --- Tidy everything up --- */ | |
146 | ||
147 | case PGEN_DONE: | |
148 | pfilt_destroy(&j->jp); | |
149 | pfilt_destroy(&j->p); | |
150 | pfilt_destroy(&j->q); | |
151 | return (PGEN_DONE); | |
1c42b462 | 152 | } |
052b36d0 | 153 | |
154 | /* --- Step on while @p@ or @q@ have small factors --- */ | |
155 | ||
156 | while (rc == PGEN_FAIL || qrc == PGEN_FAIL) { | |
157 | rc = pfilt_jump(&j->p, &j->jp); | |
158 | qrc = pfilt_jump(&j->q, &j->jq); | |
159 | } | |
160 | ev->m = MP_COPY(j->p.m); | |
161 | if (qrc == PGEN_TRY) | |
162 | rc = PGEN_TRY; | |
163 | return (rc); | |
1c42b462 | 164 | } |
165 | ||
166 | /* --- @pgen_safetest@ --- * | |
167 | * | |
168 | * Applies Rabin-Miller tests to %$p$% and %$q$%. | |
169 | */ | |
170 | ||
171 | int pgen_safetest(int rq, pgen_event *ev, void *p) | |
172 | { | |
173 | pgen_safetestctx *c = p; | |
174 | int rc = PGEN_ABORT; | |
175 | ||
176 | switch (rq) { | |
177 | case PGEN_BEGIN: | |
178 | rabin_create(&c->q, c->c.q.m); | |
179 | rabin_create(&c->p, c->c.p.m); | |
180 | rc = PGEN_TRY; | |
181 | break; | |
182 | case PGEN_TRY: { | |
191f16d5 | 183 | mp *m = mprand_range(MP_NEW, c->c.p.m, ev->r, 0); |
1c42b462 | 184 | rc = rabin_test(&c->p, m); |
191f16d5 MW |
185 | if (rc == PGEN_PASS) { |
186 | m = mprand_range(m, c->c.q.m, ev->r, 0); | |
1c42b462 | 187 | rc = rabin_test(&c->q, m); |
191f16d5 | 188 | } |
1c42b462 | 189 | mp_drop(m); |
190 | } break; | |
191 | case PGEN_DONE: | |
192 | rabin_destroy(&c->q); | |
193 | rabin_destroy(&c->p); | |
194 | break; | |
195 | } | |
196 | return (rc); | |
197 | } | |
198 | ||
199 | /*----- That's all, folks -------------------------------------------------*/ |