crypto/dsa/dsa_key.c

   1 /*
   2  * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include <time.h>
  12 #include "internal/cryptlib.h"
  13 #include <openssl/bn.h>
  14 #include "dsa_locl.h"
  15 #include <openssl/rand.h>
  16
  17 static int dsa_builtin_keygen(DSA *dsa);
  18
  19 int DSA_generate_key(DSA *dsa)
  20 {
  21     if (dsa->meth->dsa_keygen)
  22         return dsa->meth->dsa_keygen(dsa);
  23     return dsa_builtin_keygen(dsa);
  24 }
  25
  26 static int dsa_builtin_keygen(DSA *dsa)
  27 {
  28     int ok = 0;
  29     BN_CTX *ctx = NULL;
  30     BIGNUM *pub_key = NULL, *priv_key = NULL;
  31
  32     if ((ctx = BN_CTX_new()) == NULL)
  33         goto err;
  34
  35     if (dsa->priv_key == NULL) {
  36         if ((priv_key = BN_secure_new()) == NULL)
  37             goto err;
  38     } else
  39         priv_key = dsa->priv_key;
  40
  41     do
  42         if (!BN_rand_range(priv_key, dsa->q))
  43             goto err;
  44     while (BN_is_zero(priv_key)) ;
  45
  46     if (dsa->pub_key == NULL) {
  47         if ((pub_key = BN_new()) == NULL)
  48             goto err;
  49     } else
  50         pub_key = dsa->pub_key;
  51
  52     {
  53         BIGNUM *prk = BN_new();
  54
  55         if (prk == NULL)
  56             goto err;
  57         BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME);
  58
  59         if (!BN_mod_exp(pub_key, dsa->g, prk, dsa->p, ctx)) {
  60             BN_free(prk);
  61             goto err;
  62         }
  63         /* We MUST free prk before any further use of priv_key */
  64         BN_free(prk);
  65     }
  66
  67     dsa->priv_key = priv_key;
  68     dsa->pub_key = pub_key;
  69     ok = 1;
  70
  71  err:
  72     if (pub_key != dsa->pub_key)
  73         BN_free(pub_key);
  74     if (priv_key != dsa->priv_key)
  75         BN_free(priv_key);
  76     BN_CTX_free(ctx);
  77     return (ok);
  78 }