sexp2dsa.c

   1 /* sexp2dsa.c
   2
   3    Copyright (C) 2002 Niels Möller
   4
   5    This file is part of GNU Nettle.
   6
   7    GNU Nettle is free software: you can redistribute it and/or
   8    modify it under the terms of either:
   9
  10      * the GNU Lesser General Public License as published by the Free
  11        Software Foundation; either version 3 of the License, or (at your
  12        option) any later version.
  13
  14    or
  15
  16      * the GNU General Public License as published by the Free
  17        Software Foundation; either version 2 of the License, or (at your
  18        option) any later version.
  19
  20    or both in parallel, as here.
  21
  22    GNU Nettle is distributed in the hope that it will be useful,
  23    but WITHOUT ANY WARRANTY; without even the implied warranty of
  24    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  25    General Public License for more details.
  26
  27    You should have received copies of the GNU General Public License and
  28    the GNU Lesser General Public License along with this program.  If
  29    not, see http://www.gnu.org/licenses/.
  30 */
  31
  32 #if HAVE_CONFIG_H
  33 # include "config.h"
  34 #endif
  35
  36 #include <string.h>
  37
  38 #include "dsa.h"
  39
  40 #include "bignum.h"
  41 #include "sexp.h"
  42
  43 #define GET(x, l, v)                            \
  44 do {                                            \
  45   if (!nettle_mpz_set_sexp((x), (l), (v))       \
  46       || mpz_sgn(x) <= 0)                       \
  47     return 0;                                   \
  48 } while(0)
  49
  50 /* Iterator should point past the algorithm tag, e.g.
  51  *
  52  *   (public-key (dsa (p |xxxx|) ...)
  53  *                    ^ here
  54  */
  55
  56 int
  57 dsa_keypair_from_sexp_alist(struct dsa_params *params,
  58                             mpz_t pub,
  59                             mpz_t priv,
  60                             unsigned p_max_bits,
  61                             unsigned q_bits,
  62                             struct sexp_iterator *i)
  63 {
  64   static const char * const names[5]
  65     = { "p", "q", "g", "y", "x" };
  66   struct sexp_iterator values[5];
  67   unsigned nvalues = priv ? 5 : 4;
  68   unsigned p_bits;
  69
  70   if (!sexp_iterator_assoc(i, nvalues, names, values))
  71     return 0;
  72
  73   GET(params->p, p_max_bits, &values[0]);
  74   p_bits = mpz_sizeinbase (params->p, 2);
  75   GET(params->q, q_bits ? q_bits : p_bits, &values[1]);
  76   if (q_bits > 0 && mpz_sizeinbase(params->q, 2) != q_bits)
  77     return 0;
  78   if (mpz_cmp (params->q, params->p) >= 0)
  79     return 0;
  80   GET(params->g, p_bits, &values[2]);
  81   if (mpz_cmp (params->g, params->p) >= 0)
  82     return 0;
  83   GET(pub, p_bits, &values[3]);
  84   if (mpz_cmp (pub, params->p) >= 0)
  85     return 0;
  86
  87   if (priv)
  88     {
  89       GET(priv, mpz_sizeinbase (params->q, 2), &values[4]);
  90       if (mpz_cmp (priv, params->q) >= 0)
  91         return 0;
  92     }
  93
  94   return 1;
  95 }
  96
  97 int
  98 dsa_sha1_keypair_from_sexp(struct dsa_params *params,
  99                            mpz_t pub,
 100                            mpz_t priv,
 101                            unsigned p_max_bits,
 102                            size_t length, const uint8_t *expr)
 103 {
 104   struct sexp_iterator i;
 105
 106   return sexp_iterator_first(&i, length, expr)
 107     && sexp_iterator_check_type(&i, priv ? "private-key" : "public-key")
 108     && sexp_iterator_check_type(&i, "dsa")
 109     && dsa_keypair_from_sexp_alist(params, pub, priv,
 110                                    p_max_bits, DSA_SHA1_Q_BITS, &i);
 111 }
 112
 113 int
 114 dsa_sha256_keypair_from_sexp(struct dsa_params *params,
 115                              mpz_t pub,
 116                              mpz_t priv,
 117                              unsigned p_max_bits,
 118                              size_t length, const uint8_t *expr)
 119 {
 120   struct sexp_iterator i;
 121
 122   return sexp_iterator_first(&i, length, expr)
 123     && sexp_iterator_check_type(&i, priv ? "private-key" : "public-key")
 124     && sexp_iterator_check_type(&i, "dsa-sha256")
 125     && dsa_keypair_from_sexp_alist(params, pub, priv,
 126                                    p_max_bits, DSA_SHA256_Q_BITS, &i);
 127 }
 128
 129 int
 130 dsa_signature_from_sexp(struct dsa_signature *rs,
 131                         struct sexp_iterator *i,
 132                         unsigned q_bits)
 133 {
 134   static const char * const names[2] = { "r", "s" };
 135   struct sexp_iterator values[2];
 136
 137   if (!sexp_iterator_assoc(i, 2, names, values))
 138     return 0;
 139
 140   GET(rs->r, q_bits, &values[0]);
 141   GET(rs->s, q_bits, &values[1]);
 142
 143   return 1;
 144 }