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   1 /* -*-c-*-
   2  *
   3  * $Id: hmac.h,v 1.2 1999/12/10 23:17:39 mdw Exp $
   4  *
   5  * Generic code for HMAC and NMAC
   6  *
   7  * (c) 1998 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: hmac.h,v $
  33  * Revision 1.2  1999/12/10 23:17:39  mdw
  34  * Split mode macros into interface and implementation.
  35  *
  36  * Revision 1.1  1999/09/03 08:41:12  mdw
  37  * Initial import.
  38  *
  39  */
  40
  41 /*----- Notes on the HMAC and NMAC constructions --------------------------*
  42  *
  43  * Designed by Mihir Bellare, Ran Canetti and Hugo Krawczyk, NMAC is a method
  44  * for constructing keyed message authentication algorithms from unkeyed hash
  45  * functions.  It has been proven to provide useful security given reasonable
  46  * assumptions about the underlying hash function.  HMAC is an alternative
  47  * formulation which doesn't require low-level access to the hash function's
  48  * implementation.  NMAC was designed to allow MD5 has a suitable underlying
  49  * hash function, even though doubts were already being raised about its
  50  * collision resistance.
  51  */
  52
  53 #ifndef CATACOMB_HMAC_H
  54 #define CATACOMB_HMAC_H
  55
  56 #ifdef __cplusplus
  57   extern "C" {
  58 #endif
  59
  60 /*----- Header files ------------------------------------------------------*/
  61
  62 #include <stddef.h>
  63
  64 #include <mLib/bits.h>
  65
  66 #ifndef CATACOMB_GMAC_H
  67 #  include "gmac.h"
  68 #endif
  69
  70 /*----- Macros ------------------------------------------------------------*/
  71
  72 /* --- @HMAC_DECL@ --- *
  73  *
  74  * Arguments:   @PRE@, @pre@ = prefixes for the underlying hash function
  75  *
  76  * Use:         Creates declarations for the HMAC and NMAC functions.
  77  */
  78
  79 #define HMAC_DECL(PRE, pre)                                             \
  80                                                                         \
  81 /* --- An HMAC or NMAC key --- */                                       \
  82                                                                         \
  83 typedef struct pre##_mackey {                                           \
  84   octet ochain[PRE##_HASHSZ];           /* Chaining for outer hash */   \
  85   unsigned ocount;                      /* Byte count for outer hash */ \
  86   octet ichain[PRE##_HASHSZ];           /* Chaining for inner hash */   \
  87   unsigned icount;                      /* Byte count for inner hash */ \
  88 } pre##_mackey;                                                         \
  89                                                                         \
  90 /* --- An HMAC or NMAC hashing context --- */                           \
  91                                                                         \
  92 typedef struct pre##_macctx {                                           \
  93   pre##_ctx ctx;                        /* Context for main hashing */  \
  94   octet chain[PRE##_HASHSZ];            /* Chaining for outer hash */   \
  95   unsigned count;                       /* Byte count for outer hash */ \
  96 } pre##_macctx;                                                         \
  97                                                                         \
  98 /* --- @pre_nmacinit@ --- *                                             \
  99  *                                                                      \
 100  * Arguments:   @pre_macctx *key@ = pointer to a MAC key object         \
 101  *              @const void *ok@ = pointer to outer hash init vector    \
 102  *              @const void *ik@ = pointer to inner hash init vector    \
 103  *                                                                      \
 104  * Returns:     ---                                                     \
 105  *                                                                      \
 106  * Use:         Initializes a MAC key for doing NMAC hashing.           \
 107  */                                                                     \
 108                                                                         \
 109 extern void pre##_nmacinit(pre##_mackey */*key*/,                       \
 110                            const void */*ok*/, const void */*ik*/);     \
 111                                                                         \
 112 /* --- @pre_hmacinit@ --- *                                             \
 113  *                                                                      \
 114  * Arguments:   @pre_mackey *key@ = pointer to MAC key object           \
 115  *              @const void *k@ = pointer to key to use                 \
 116  *              @size_t sz@ = size of key data                          \
 117  *                                                                      \
 118  * Returns:     ---                                                     \
 119  *                                                                      \
 120  * Use:         Initializes a MAC key for doing HMAC hashing.  Keys     \
 121  *              longer than the hash function's output size aren't very \
 122  *              useful, but are accepted.  Keys longer than the hash's  \
 123  *              block size are also accepted; they are hashed before    \
 124  *              use, as specified in RFC2104.                           \
 125  */                                                                     \
 126                                                                         \
 127 extern void pre##_hmacinit(pre##_mackey */*key*/,                       \
 128                            const void */*k*/, size_t /*sz*/);           \
 129                                                                         \
 130 /* --- @pre_macinit@ --- *                                              \
 131  *                                                                      \
 132  * Arguments:   @pre_macctx *ctx@ = pointer to MAC context block        \
 133  *              @const pre_mackey *key@ = pointer to MAC key block      \
 134  *                                                                      \
 135  * Returns:     ---                                                     \
 136  *                                                                      \
 137  * Use:         Instantiates a MAC context from a key block.            \
 138  */                                                                     \
 139                                                                         \
 140 extern void pre##_macinit(pre##_macctx */*ctx*/,                        \
 141                           const pre##_mackey */*key*/);                 \
 142                                                                         \
 143 /* --- @pre_machash@ --- *                                              \
 144  *                                                                      \
 145  * Arguments:   @pre_macctx *ctx@ = pointer to MAC context block        \
 146  *              @const void *buf@ = pointer to buffer                   \
 147  *              @size_t sz@ = size of the buffer                        \
 148  *                                                                      \
 149  * Returns:     ---                                                     \
 150  *                                                                      \
 151  * Use:         Hashes a buffer.                                        \
 152  */                                                                     \
 153                                                                         \
 154 extern void pre##_machash(pre##_macctx */*ctx*/,                        \
 155                           const void */*buf*/, size_t /*sz*/);          \
 156                                                                         \
 157 /* --- @pre_macdone@ --- *                                              \
 158  *                                                                      \
 159  * Arguments:   @pre_macctx *ctx@ = pointer to MAC context block        \
 160  *              @void *mac@ = pointer to buffer to receive MAC          \
 161  *                                                                      \
 162  * Returns:     ---                                                     \
 163  *                                                                      \
 164  * Use:         Returns the result of a MAC computation.                \
 165  */                                                                     \
 166                                                                         \
 167 extern void pre##_macdone(pre##_macctx */*ctx*/, void */*mac*/);        \
 168                                                                         \
 169 /* --- Generic MAC interface --- */                                     \
 170                                                                         \
 171 extern const gcmac pre##_hmac;
 172
 173 /*----- That's all, folks -------------------------------------------------*/
 174
 175 #ifdef __cplusplus
 176   }
 177 #endif
 178
 179 #endif