| 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 | /** @brief DisOrder algorithm name */ |
| 32 | const char *name; |
| 33 | |
| 34 | /** @brief gcrypt algorithm ID */ |
| 35 | int id; |
| 36 | }; |
| 37 | |
| 38 | /** @brief Algorithm lookup table |
| 39 | * |
| 40 | * We don't use gcry_md_map_name() since that would import gcrypt's API into |
| 41 | * the disorder protocol. |
| 42 | */ |
| 43 | static const struct algorithm algorithms[] = { |
| 44 | { "SHA1", GCRY_MD_SHA1 }, |
| 45 | { "sha1", GCRY_MD_SHA1 }, |
| 46 | { "SHA256", GCRY_MD_SHA256 }, |
| 47 | { "sha256", GCRY_MD_SHA256 }, |
| 48 | { "SHA384", GCRY_MD_SHA384 }, |
| 49 | { "sha384", GCRY_MD_SHA384 }, |
| 50 | { "SHA512", GCRY_MD_SHA512 }, |
| 51 | { "sha512", GCRY_MD_SHA512 }, |
| 52 | }; |
| 53 | |
| 54 | /** @brief Number of supported algorithms */ |
| 55 | #define NALGORITHMS (sizeof algorithms / sizeof *algorithms) |
| 56 | |
| 57 | /** @brief Perform the authorization hash function |
| 58 | * @param challenge Pointer to challange |
| 59 | * @param nchallenge Size of challenge |
| 60 | * @param password Password |
| 61 | * @param algo Algorithm to use |
| 62 | * @return Hex string or NULL on error |
| 63 | * |
| 64 | * Computes H(challenge|password) and returns it as a newly allocated hex |
| 65 | * string, or returns NULL on error. |
| 66 | */ |
| 67 | const char *authhash(const void *challenge, size_t nchallenge, |
| 68 | const char *password, const char *algo) { |
| 69 | gcrypt_hash_handle h; |
| 70 | const char *res; |
| 71 | size_t n; |
| 72 | int id; |
| 73 | |
| 74 | assert(challenge != 0); |
| 75 | assert(password != 0); |
| 76 | assert(algo != 0); |
| 77 | for(n = 0; n < NALGORITHMS; ++n) |
| 78 | if(!strcmp(algo, algorithms[n].name)) |
| 79 | break; |
| 80 | if(n >= NALGORITHMS) |
| 81 | return NULL; |
| 82 | id = algorithms[n].id; |
| 83 | #if HAVE_GCRY_ERROR_T |
| 84 | { |
| 85 | gcry_error_t e; |
| 86 | |
| 87 | if((e = gcry_md_open(&h, id, 0))) { |
| 88 | disorder_error(0, "gcry_md_open: %s", gcry_strerror(e)); |
| 89 | return 0; |
| 90 | } |
| 91 | } |
| 92 | #else |
| 93 | h = gcry_md_open(id, 0); |
| 94 | #endif |
| 95 | gcry_md_write(h, password, strlen(password)); |
| 96 | gcry_md_write(h, challenge, nchallenge); |
| 97 | res = hex(gcry_md_read(h, id), gcry_md_get_algo_dlen(id)); |
| 98 | gcry_md_close(h); |
| 99 | return res; |
| 100 | } |
| 101 | |
| 102 | /** @brief Return non-zero if @p algo is a valid algorithm */ |
| 103 | int valid_authhash(const char *algo) { |
| 104 | size_t n; |
| 105 | |
| 106 | for(n = 0; n < NALGORITHMS; ++n) |
| 107 | if(!strcmp(algo, algorithms[n].name)) |
| 108 | return 1; |
| 109 | return 0; |
| 110 | } |
| 111 | |
| 112 | /* |
| 113 | Local Variables: |
| 114 | c-basic-offset:2 |
| 115 | comment-column:40 |
| 116 | fill-column:79 |
| 117 | End: |
| 118 | */ |