3 * $Id: hmac.h,v 1.4 2000/10/15 19:09:20 mdw Exp $
5 * Generic code for HMAC and NMAC
7 * (c) 1998 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.4 2000/10/15 19:09:20 mdw
34 * Support HMAC mode for hash functions which need to store more state than
35 * the hash output size.
37 * Revision 1.3 2000/06/17 11:23:57 mdw
38 * New key size interface.
40 * Revision 1.2 1999/12/10 23:17:39 mdw
41 * Split mode macros into interface and implementation.
43 * Revision 1.1 1999/09/03 08:41:12 mdw
48 /*----- Notes on the HMAC and NMAC constructions --------------------------*
50 * Designed by Mihir Bellare, Ran Canetti and Hugo Krawczyk, NMAC is a method
51 * for constructing keyed message authentication algorithms from unkeyed hash
52 * functions. It has been proven to provide useful security given reasonable
53 * assumptions about the underlying hash function. HMAC is an alternative
54 * formulation which doesn't require low-level access to the hash function's
55 * implementation. NMAC was designed to allow MD5 has a suitable underlying
56 * hash function, even though doubts were already being raised about its
57 * collision resistance.
60 #ifndef CATACOMB_HMAC_H
61 #define CATACOMB_HMAC_H
67 /*----- Header files ------------------------------------------------------*/
71 #include <mLib/bits.h>
73 #ifndef CATACOMB_GMAC_H
77 /*----- Macros ------------------------------------------------------------*/
79 /* --- @HMAC_DECL@ --- *
81 * Arguments: @PRE@, @pre@ = prefixes for the underlying hash function
83 * Use: Creates declarations for the HMAC and NMAC functions.
86 #define HMAC_DECL(PRE, pre) \
88 /* --- An HMAC or NMAC key --- */ \
90 typedef struct pre##_mackey { \
91 octet ochain[PRE##_STATESZ]; /* Chaining for outer hash */ \
92 unsigned ocount; /* Byte count for outer hash */ \
93 octet ichain[PRE##_STATESZ]; /* Chaining for inner hash */ \
94 unsigned icount; /* Byte count for inner hash */ \
97 /* --- An HMAC or NMAC hashing context --- */ \
99 typedef struct pre##_macctx { \
100 pre##_ctx ctx; /* Context for main hashing */ \
101 octet chain[PRE##_STATESZ]; /* Chaining for outer hash */ \
102 unsigned count; /* Byte count for outer hash */ \
105 /* --- Other useful constants --- */ \
107 extern const octet pre##_mackeysz[]; \
109 /* --- @pre_nmacinit@ --- * \
111 * Arguments: @pre_macctx *key@ = pointer to a MAC key object \
112 * @const void *ok@ = pointer to outer hash init vector \
113 * @const void *ik@ = pointer to inner hash init vector \
117 * Use: Initializes a MAC key for doing NMAC hashing. \
120 extern void pre##_nmacinit(pre##_mackey */*key*/, \
121 const void */*ok*/, const void */*ik*/); \
123 /* --- @pre_hmacinit@ --- * \
125 * Arguments: @pre_mackey *key@ = pointer to MAC key object \
126 * @const void *k@ = pointer to key to use \
127 * @size_t sz@ = size of key data \
131 * Use: Initializes a MAC key for doing HMAC hashing. Keys \
132 * longer than the hash function's output size aren't very \
133 * useful, but are accepted. Keys longer than the hash's \
134 * block size are also accepted; they are hashed before \
135 * use, as specified in RFC2104. \
138 extern void pre##_hmacinit(pre##_mackey */*key*/, \
139 const void */*k*/, size_t /*sz*/); \
141 /* --- @pre_macinit@ --- * \
143 * Arguments: @pre_macctx *ctx@ = pointer to MAC context block \
144 * @const pre_mackey *key@ = pointer to MAC key block \
148 * Use: Instantiates a MAC context from a key block. \
151 extern void pre##_macinit(pre##_macctx */*ctx*/, \
152 const pre##_mackey */*key*/); \
154 /* --- @pre_machash@ --- * \
156 * Arguments: @pre_macctx *ctx@ = pointer to MAC context block \
157 * @const void *buf@ = pointer to buffer \
158 * @size_t sz@ = size of the buffer \
162 * Use: Hashes a buffer. \
165 extern void pre##_machash(pre##_macctx */*ctx*/, \
166 const void */*buf*/, size_t /*sz*/); \
168 /* --- @pre_macdone@ --- * \
170 * Arguments: @pre_macctx *ctx@ = pointer to MAC context block \
171 * @void *mac@ = pointer to buffer to receive MAC \
175 * Use: Returns the result of a MAC computation. \
178 extern void pre##_macdone(pre##_macctx */*ctx*/, void */*mac*/); \
180 /* --- Generic MAC interface --- */ \
182 extern const gcmac pre##_hmac;
184 /*----- That's all, folks -------------------------------------------------*/