lib/gnutls_psk_netconf.c

   1 /*
   2  * Copyright (C) 2008, 2010 Free Software Foundation, Inc.
   3  *
   4  * Author: Simon Josefsson
   5  *
   6  * This file is part of GNUTLS.
   7  *
   8  * The GNUTLS library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public License
  10  * as published by the Free Software Foundation; either version 2.1 of
  11  * the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful, but
  14  * WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
  21  * USA
  22  *
  23  */
  24
  25 /* Functions to support draft-ietf-netconf-tls-01.txt. */
  26
  27 #include <gnutls_int.h>
  28 #include <gnutls_hash_int.h>
  29 #include <gnutls_errors.h>
  30
  31 #ifdef ENABLE_PSK
  32
  33
  34 /**
  35  * gnutls_psk_netconf_derive_key:
  36  * @password: zero terminated string containing password.
  37  * @psk_identity: zero terminated string with PSK identity.
  38  * @psk_identity_hint: zero terminated string with PSK identity hint.
  39  * @output_key: output variable, contains newly allocated *data pointer.
  40  *
  41  * This function will derive a PSK key from a password, for use with
  42  * the Netconf protocol.
  43  *
  44  * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
  45  *
  46  * Since: 2.4.0
  47  **/
  48 int
  49 gnutls_psk_netconf_derive_key (const char *password,
  50                                const char *psk_identity,
  51                                const char *psk_identity_hint,
  52                                gnutls_datum_t * output_key)
  53 {
  54   const char netconf_key_pad[] = "Key Pad for Netconf";
  55   size_t sha1len = _gnutls_hash_get_algo_len (GNUTLS_DIG_SHA1);
  56   size_t hintlen = strlen (psk_identity_hint);
  57   digest_hd_st dig;
  58   char *inner;
  59   size_t innerlen;
  60   int rc;
  61
  62   /*
  63    * PSK = SHA-1(SHA-1(psk_identity + "Key Pad for Netconf" + password) +
  64    *             psk_identity_hint)
  65    *
  66    */
  67
  68   rc = _gnutls_hash_init (&dig, GNUTLS_DIG_SHA1);
  69   if (rc < 0)
  70     {
  71       gnutls_assert ();
  72       return rc;
  73     }
  74
  75   rc = _gnutls_hash (&dig, psk_identity, strlen (psk_identity));
  76   if (rc < 0)
  77     {
  78       gnutls_assert ();
  79       _gnutls_hash_deinit (&dig, NULL);
  80       return rc;
  81     }
  82
  83   rc = _gnutls_hash (&dig, netconf_key_pad, strlen (netconf_key_pad));
  84   if (rc < 0)
  85     {
  86       gnutls_assert ();
  87       _gnutls_hash_deinit (&dig, NULL);
  88       return rc;
  89     }
  90
  91   rc = _gnutls_hash (&dig, password, strlen (password));
  92   if (rc < 0)
  93     {
  94       gnutls_assert ();
  95       _gnutls_hash_deinit (&dig, NULL);
  96       return rc;
  97     }
  98
  99   innerlen = sha1len + hintlen;
 100   inner = gnutls_malloc (innerlen);
 101   _gnutls_hash_deinit (&dig, inner);
 102   if (inner == NULL)
 103     {
 104       gnutls_assert ();
 105       return GNUTLS_E_MEMORY_ERROR;
 106     }
 107
 108   memcpy (inner + sha1len, psk_identity_hint, hintlen);
 109
 110   rc = _gnutls_hash_init (&dig, GNUTLS_DIG_SHA1);
 111   if (rc < 0)
 112     {
 113       gnutls_assert ();
 114       gnutls_free (inner);
 115       return rc;
 116     }
 117
 118   rc = _gnutls_hash (&dig, inner, innerlen);
 119   gnutls_free (inner);
 120   if (rc < 0)
 121     {
 122       gnutls_assert ();
 123       _gnutls_hash_deinit (&dig, NULL);
 124       return rc;
 125     }
 126
 127   output_key->data = gnutls_malloc (sha1len);
 128   _gnutls_hash_deinit (&dig, output_key->data);
 129   if (output_key->data == NULL)
 130     {
 131       gnutls_assert ();
 132       return GNUTLS_E_MEMORY_ERROR;
 133     }
 134   output_key->size = sha1len;
 135
 136   return 0;
 137 }
 138
 139 #endif /* ENABLE_PSK */