1c42b462 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: pgen-safe.c,v 1.1 1999/12/22 16:01:34 mdw Exp $ |
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 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: pgen-safe.c,v $ |
33 | * Revision 1.1 1999/12/22 16:01:34 mdw |
34 | * Find `safe' primes (i.e., %$p = 2q + 1$%). |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include "mp.h" |
41 | #include "mprand.h" |
42 | #include "pgen.h" |
43 | |
44 | /*----- Main code ---------------------------------------------------------*/ |
45 | |
46 | /* --- @pgen_safestep@ --- * |
47 | * |
48 | * Steps two numbers, %$q$% and %$p = 2q + 1$%, such that neither has any |
49 | * small factors. %$p$% is put in the event block. |
50 | */ |
51 | |
52 | int pgen_safestep(int rq, pgen_event *ev, void *p) |
53 | { |
54 | pgen_safestepctx *c = p; |
55 | int prc = PGEN_ABORT, qrc; |
56 | |
57 | switch (rq) { |
58 | case PGEN_BEGIN: { |
59 | mp *p = mp_split(MP_COPY(ev->m)); |
60 | mp *q; |
61 | p->v[0] |= 3; |
62 | q = mp_lsr(MP_NEW, p, 1); |
63 | qrc = pfilt_create(&c->q, q); |
64 | prc = pfilt_create(&c->p, p); |
65 | mp_drop(p); |
66 | mp_drop(q); |
67 | } goto step; |
68 | case PGEN_TRY: |
69 | again: |
70 | qrc = pfilt_step(&c->q, 2); |
71 | prc = pfilt_step(&c->p, 4); |
72 | step: |
73 | if (qrc == PGEN_FAIL || prc == PGEN_FAIL) |
74 | goto again; |
75 | mp_drop(ev->m); |
76 | ev->m = MP_COPY(c->p.m); |
77 | if (qrc == PGEN_TRY) |
78 | prc = PGEN_TRY; |
79 | break; |
80 | case PGEN_DONE: |
81 | pfilt_destroy(&c->q); |
82 | pfilt_destroy(&c->p); |
83 | break; |
84 | } |
85 | return (prc); |
86 | } |
87 | |
88 | /* --- @pgen_safetest@ --- * |
89 | * |
90 | * Applies Rabin-Miller tests to %$p$% and %$q$%. |
91 | */ |
92 | |
93 | int pgen_safetest(int rq, pgen_event *ev, void *p) |
94 | { |
95 | pgen_safetestctx *c = p; |
96 | int rc = PGEN_ABORT; |
97 | |
98 | switch (rq) { |
99 | case PGEN_BEGIN: |
100 | rabin_create(&c->q, c->c.q.m); |
101 | rabin_create(&c->p, c->c.p.m); |
102 | rc = PGEN_TRY; |
103 | break; |
104 | case PGEN_TRY: { |
105 | mp *m = mprand_range(MP_NEW, c->c.q.m, ev->r, 0); |
106 | rc = rabin_test(&c->p, m); |
107 | if (rc == PGEN_PASS) |
108 | rc = rabin_test(&c->q, m); |
109 | mp_drop(m); |
110 | } break; |
111 | case PGEN_DONE: |
112 | rabin_destroy(&c->q); |
113 | rabin_destroy(&c->p); |
114 | break; |
115 | } |
116 | return (rc); |
117 | } |
118 | |
119 | /*----- That's all, folks -------------------------------------------------*/ |