mdw@git.distorted.org.uk Git - disorder/blob - lib/authhash.c

   1 /*
   2  * This file is part of DisOrder
   3  * Copyright (C) 2004, 2006, 2007 Richard Kettlewell
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation, either version 3 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18 /** @file lib/authhash.c @brief The authorization hash */
  19
  20 #include "common.h"
  21
  22 #include <stddef.h>
  23 #include <gcrypt.h>
  24
  25 #include "hex.h"
  26 #include "log.h"
  27 #include "authhash.h"
  28
  29 /** @brief Structure of algorithm lookup table */
  30 struct algorithm {
  31   const char *name;
  32   int id;
  33 };
  34
  35 /** @brief Algorithm lookup table
  36  *
  37  * We don't use gcry_md_map_name() since that would import gcrypt's API into
  38  * the disorder protocol.
  39  */
  40 static const struct algorithm algorithms[] = {
  41   { "SHA1", GCRY_MD_SHA1 },
  42   { "sha1", GCRY_MD_SHA1 },
  43   { "SHA256", GCRY_MD_SHA256 },
  44   { "sha256", GCRY_MD_SHA256 },
  45   { "SHA384", GCRY_MD_SHA384 },
  46   { "sha384", GCRY_MD_SHA384 },
  47   { "SHA512", GCRY_MD_SHA512 },
  48   { "sha512", GCRY_MD_SHA512 },
  49 };
  50
  51 /** @brief Number of supported algorithms */
  52 #define NALGORITHMS (sizeof algorithms / sizeof *algorithms)
  53
  54 /** @brief Perform the authorization hash function
  55  * @param challenge Pointer to challange
  56  * @param nchallenge Size of challenge
  57  * @param password Password
  58  * @param algo Algorithm to use
  59  *
  60  * Computes H(challenge|password) and returns it as a newly allocated hex
  61  * string, or returns NULL on error.
  62  */
  63 const char *authhash(const void *challenge, size_t nchallenge,
  64                      const char *password, const char *algo) {
  65   gcrypt_hash_handle h;
  66   const char *res;
  67   size_t n;
  68   int id;
  69
  70   assert(challenge != 0);
  71   assert(password != 0);
  72   assert(algo != 0);
  73   for(n = 0; n < NALGORITHMS; ++n)
  74     if(!strcmp(algo, algorithms[n].name))
  75       break;
  76   if(n >= NALGORITHMS)
  77     return NULL;
  78   id = algorithms[n].id;
  79 #if HAVE_GCRY_ERROR_T
  80   {
  81     gcry_error_t e;
  82
  83     if((e = gcry_md_open(&h, id, 0))) {
  84       error(0, "gcry_md_open: %s", gcry_strerror(e));
  85       return 0;
  86     }
  87   }
  88 #else
  89   h = gcry_md_open(id, 0);
  90 #endif
  91   gcry_md_write(h, password, strlen(password));
  92   gcry_md_write(h, challenge, nchallenge);
  93   res = hex(gcry_md_read(h, id), gcry_md_get_algo_dlen(id));
  94   gcry_md_close(h);
  95   return res;
  96 }
  97
  98 /** @brief Return non-zero if @p algo is a valid algorithm */
  99 int valid_authhash(const char *algo) {
 100   size_t n;
 101
 102   for(n = 0; n < NALGORITHMS; ++n)
 103     if(!strcmp(algo, algorithms[n].name))
 104       return 1;
 105   return 0;
 106 }
 107
 108 /*
 109 Local Variables:
 110 c-basic-offset:2
 111 comment-column:40
 112 fill-column:79
 113 End:
 114 */