3 * $Id: hmac.h,v 1.2 1999/12/10 23:17:39 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 1.2 1999/12/10 23:17:39 mdw
34 * Split mode macros into interface and implementation.
36 * Revision 1.1 1999/09/03 08:41:12 mdw
41 /*----- Notes on the HMAC and NMAC constructions --------------------------*
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.
53 #ifndef CATACOMB_HMAC_H
54 #define CATACOMB_HMAC_H
60 /*----- Header files ------------------------------------------------------*/
64 #include <mLib/bits.h>
66 #ifndef CATACOMB_GMAC_H
70 /*----- Macros ------------------------------------------------------------*/
72 /* --- @HMAC_DECL@ --- *
74 * Arguments: @PRE@, @pre@ = prefixes for the underlying hash function
76 * Use: Creates declarations for the HMAC and NMAC functions.
79 #define HMAC_DECL(PRE, pre) \
81 /* --- An HMAC or NMAC key --- */ \
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 */ \
90 /* --- An HMAC or NMAC hashing context --- */ \
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 */ \
98 /* --- @pre_nmacinit@ --- * \
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 \
106 * Use: Initializes a MAC key for doing NMAC hashing. \
109 extern void pre##_nmacinit(pre##_mackey */*key*/, \
110 const void */*ok*/, const void */*ik*/); \
112 /* --- @pre_hmacinit@ --- * \
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 \
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. \
127 extern void pre##_hmacinit(pre##_mackey */*key*/, \
128 const void */*k*/, size_t /*sz*/); \
130 /* --- @pre_macinit@ --- * \
132 * Arguments: @pre_macctx *ctx@ = pointer to MAC context block \
133 * @const pre_mackey *key@ = pointer to MAC key block \
137 * Use: Instantiates a MAC context from a key block. \
140 extern void pre##_macinit(pre##_macctx */*ctx*/, \
141 const pre##_mackey */*key*/); \
143 /* --- @pre_machash@ --- * \
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 \
151 * Use: Hashes a buffer. \
154 extern void pre##_machash(pre##_macctx */*ctx*/, \
155 const void */*buf*/, size_t /*sz*/); \
157 /* --- @pre_macdone@ --- * \
159 * Arguments: @pre_macctx *ctx@ = pointer to MAC context block \
160 * @void *mac@ = pointer to buffer to receive MAC \
164 * Use: Returns the result of a MAC computation. \
167 extern void pre##_macdone(pre##_macctx */*ctx*/, void */*mac*/); \
169 /* --- Generic MAC interface --- */ \
171 extern const gcmac pre##_hmac;
173 /*----- That's all, folks -------------------------------------------------*/