| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Consistency checking for DSA keys |
| 4 | * |
| 5 | * (c) 2001 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 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. |
| 16 | * |
| 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. |
| 21 | * |
| 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 | |
| 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 -------------------------------------------------*/ |