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1 | /* -*-c-*- |
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2 | * |
3 | * Consistency checking for DSA keys |
4 | * |
5 | * (c) 2001 Straylight/Edgeware |
6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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9 | * |
10 | * This file is part of Catacomb. |
11 | * |
12 | * Catacomb is free software; you can redistribute it and/or modify |
13 | * it under the terms of the GNU Library General Public License as |
14 | * published by the Free Software Foundation; either version 2 of the |
15 | * License, or (at your option) any later version. |
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16 | * |
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17 | * Catacomb is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU Library General Public License for more details. |
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21 | * |
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22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with Catacomb; if not, write to the Free |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
25 | * MA 02111-1307, USA. |
26 | */ |
27 | |
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28 | /*----- Header files ------------------------------------------------------*/ |
29 | |
30 | #include "dh.h" |
31 | #include "dsa.h" |
32 | #include "dsarand.h" |
33 | #include "grand.h" |
34 | #include "keycheck.h" |
35 | #include "mp.h" |
36 | #include "mprand.h" |
37 | |
38 | /*----- Main code ---------------------------------------------------------*/ |
39 | |
40 | /* --- @dsa_checkparam@ --- * |
41 | * |
42 | * Arguments: @keycheck *kc@ = keycheck state |
43 | * @const dsa_param *dp@ = pointer to the parameter set |
44 | * @const dsa_seed *ds@ = pointer to seed information |
45 | * |
46 | * Returns: Zero if all OK, or return status from function. |
47 | * |
48 | * Use: Checks a set of DSA parameters for consistency and security. |
49 | */ |
50 | |
51 | int dsa_checkparam(keycheck *kc, const dsa_param *dp, const dsa_seed *ds) |
52 | { |
53 | if (ds) { |
54 | grand *r = dsarand_create(ds->p, ds->sz); |
55 | mp *p = MP_NEW, *q = MP_NEW; |
56 | int rc = 0; |
57 | unsigned i; |
58 | unsigned long n; |
59 | |
60 | r->ops->misc(r, DSARAND_PASSES, 2); |
61 | q = mprand(q, mp_bits(dp->q), r, 1); |
62 | if (!mp_eq(q, dp->q) && |
63 | keycheck_report(kc, KCSEV_ERR, "q doesn't match seed provided")) |
64 | rc = -1; |
65 | else { |
66 | n = mp_bits(dp->p); |
67 | r->ops->misc(r, DSARAND_PASSES, 1); |
68 | for (i = 0; i <= ds->count; i++) |
69 | p = mprand(p, n, r, 0); |
70 | q = mp_lsl(q, q, 1); |
71 | mp_div(0, &q, p, q); |
72 | p = mp_sub(p, p, q); |
73 | p->v[0] |= 1; |
74 | if (!mp_eq(p, dp->p) && |
75 | keycheck_report(kc, KCSEV_ERR, "p doesn't match seed provided")) |
76 | rc = -1; |
77 | } |
78 | mp_drop(p); |
79 | mp_drop(q); |
80 | r->ops->destroy(r); |
81 | if (rc) |
82 | return (rc); |
83 | } |
84 | return (dh_checkparam(kc, dp, 0, 0)); |
85 | } |
86 | |
87 | /*----- That's all, folks -------------------------------------------------*/ |