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, 2009, 2013 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 #if HAVE_GCRYPT_H
  24 # include <gcrypt.h>
  25 #else
  26 # error No crypto API available
  27 #endif
  28
  29 #include "hex.h"
  30 #include "log.h"
  31 #include "authhash.h"
  32
  33 /** @brief Structure of algorithm lookup table */
  34 struct algorithm {
  35   /** @brief DisOrder algorithm name */
  36   const char *name;
  37
  38 #if HAVE_GCRYPT_H
  39   /** @brief gcrypt algorithm ID */
  40   int id;
  41 #endif
  42
  43 };
  44
  45 /** @brief Algorithm lookup table
  46  *
  47  * We don't use gcry_md_map_name() since that would import gcrypt's API into
  48  * the disorder protocol.
  49  */
  50 static const struct algorithm algorithms[] = {
  51 #if HAVE_GCRYPT_H
  52   { "SHA1", GCRY_MD_SHA1 },
  53   { "sha1", GCRY_MD_SHA1 },
  54   { "SHA256", GCRY_MD_SHA256 },
  55   { "sha256", GCRY_MD_SHA256 },
  56   { "SHA384", GCRY_MD_SHA384 },
  57   { "sha384", GCRY_MD_SHA384 },
  58   { "SHA512", GCRY_MD_SHA512 },
  59   { "sha512", GCRY_MD_SHA512 },
  60 #endif
  61 };
  62
  63 /** @brief Number of supported algorithms */
  64 #define NALGORITHMS (sizeof algorithms / sizeof *algorithms)
  65
  66 /** @brief Perform the authorization hash function
  67  * @param challenge Pointer to challange
  68  * @param nchallenge Size of challenge
  69  * @param password Password
  70  * @param algo Algorithm to use
  71  * @return Hex string or NULL on error
  72  *
  73  * Computes H(challenge|password) and returns it as a newly allocated hex
  74  * string, or returns NULL on error.
  75  */
  76 char *authhash(const void *challenge, size_t nchallenge,
  77                const char *password, const char *algo) {
  78 #if HAVE_GCRYPT_H
  79   gcrypt_hash_handle h;
  80   int id;
  81 #endif
  82   char *res;
  83   size_t n;
  84
  85   assert(challenge != 0);
  86   assert(password != 0);
  87   assert(algo != 0);
  88   for(n = 0; n < NALGORITHMS; ++n)
  89     if(!strcmp(algo, algorithms[n].name))
  90       break;
  91   if(n >= NALGORITHMS)
  92     return NULL;
  93 #if HAVE_GCRYPT_H
  94   id = algorithms[n].id;
  95 #if HAVE_GCRY_ERROR_T
  96   {
  97     gcry_error_t e;
  98
  99     if((e = gcry_md_open(&h, id, 0))) {
 100       disorder_error(0, "gcry_md_open: %s", gcry_strerror(e));
 101       return 0;
 102     }
 103   }
 104 #else
 105   h = gcry_md_open(id, 0);
 106 #endif
 107   gcry_md_write(h, password, strlen(password));
 108   gcry_md_write(h, challenge, nchallenge);
 109   res = hex(gcry_md_read(h, id), gcry_md_get_algo_dlen(id));
 110   gcry_md_close(h);
 111 #endif
 112   return res;
 113 }
 114
 115 /** @brief Return non-zero if @p algo is a valid algorithm */
 116 int valid_authhash(const char *algo) {
 117   size_t n;
 118
 119   for(n = 0; n < NALGORITHMS; ++n)
 120     if(!strcmp(algo, algorithms[n].name))
 121       return 1;
 122   return 0;
 123 }
 124
 125 /*
 126 Local Variables:
 127 c-basic-offset:2
 128 comment-column:40
 129 fill-column:79
 130 End:
 131 */