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1 | /* -*-c-*- |
2 | * |
3 | * $Id: dsa-check.c,v 1.1 2001/02/03 16:08:24 mdw Exp $ |
4 | * |
5 | * Consistency checking for DSA keys |
6 | * |
7 | * (c) 2001 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: dsa-check.c,v $ |
33 | * Revision 1.1 2001/02/03 16:08:24 mdw |
34 | * Add consistency checking for public keys. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include "dh.h" |
41 | #include "dsa.h" |
42 | #include "dsarand.h" |
43 | #include "grand.h" |
44 | #include "keycheck.h" |
45 | #include "mp.h" |
46 | #include "mprand.h" |
47 | |
48 | /*----- Main code ---------------------------------------------------------*/ |
49 | |
50 | /* --- @dsa_checkparam@ --- * |
51 | * |
52 | * Arguments: @keycheck *kc@ = keycheck state |
53 | * @const dsa_param *dp@ = pointer to the parameter set |
54 | * @const dsa_seed *ds@ = pointer to seed information |
55 | * |
56 | * Returns: Zero if all OK, or return status from function. |
57 | * |
58 | * Use: Checks a set of DSA parameters for consistency and security. |
59 | */ |
60 | |
61 | int dsa_checkparam(keycheck *kc, const dsa_param *dp, const dsa_seed *ds) |
62 | { |
63 | if (ds) { |
64 | grand *r = dsarand_create(ds->p, ds->sz); |
65 | mp *p = MP_NEW, *q = MP_NEW; |
66 | int rc = 0; |
67 | unsigned i; |
68 | unsigned long n; |
69 | |
70 | r->ops->misc(r, DSARAND_PASSES, 2); |
71 | q = mprand(q, mp_bits(dp->q), r, 1); |
72 | if (!mp_eq(q, dp->q) && |
73 | keycheck_report(kc, KCSEV_ERR, "q doesn't match seed provided")) |
74 | rc = -1; |
75 | else { |
76 | n = mp_bits(dp->p); |
77 | r->ops->misc(r, DSARAND_PASSES, 1); |
78 | for (i = 0; i <= ds->count; i++) |
79 | p = mprand(p, n, r, 0); |
80 | q = mp_lsl(q, q, 1); |
81 | mp_div(0, &q, p, q); |
82 | p = mp_sub(p, p, q); |
83 | p->v[0] |= 1; |
84 | if (!mp_eq(p, dp->p) && |
85 | keycheck_report(kc, KCSEV_ERR, "p doesn't match seed provided")) |
86 | rc = -1; |
87 | } |
88 | mp_drop(p); |
89 | mp_drop(q); |
90 | r->ops->destroy(r); |
91 | if (rc) |
92 | return (rc); |
93 | } |
94 | return (dh_checkparam(kc, dp, 0, 0)); |
95 | } |
96 | |
97 | /*----- That's all, folks -------------------------------------------------*/ |