50d61fadcc70bd9b62e283a969750b8f86d71dce
[u/mdw/catacomb] / sha256.h
1 /* -*-c-*-
2 *
3 * $Id: sha256.h,v 1.2 2000/10/15 19:09:20 mdw Exp $
4 *
5 * Implementation of the SHA-256 hash function
6 *
7 * (c) 2000 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: sha256.h,v $
33 * Revision 1.2 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.
36 *
37 * Revision 1.1 2000/10/15 17:48:15 mdw
38 * New SHA variants with longer outputs.
39 *
40 */
41
42 /*----- Notes on the SHA-256 hash function ----------------------------------*
43 *
44 * SHA-1 (Secure Hash Algorithm) was designed by the NSA, for use with the
45 * Digital Signature Algorithm. This is an evolution with a larger output
46 * size, intended to provide security commensurate with 128-bit AES. At the
47 * time of writing, SHA-256 is very new, and can't be trusted too far.
48 */
49
50 #ifndef CATACOMB_SHA256_H
51 #define CATACOMB_SHA256_H
52
53 #ifdef __cplusplus
54 extern "C" {
55 #endif
56
57 /*----- Header files ------------------------------------------------------*/
58
59 #include <mLib/bits.h>
60
61 #ifndef CATACOMB_GHASH_H
62 # include "ghash.h"
63 #endif
64
65 /*----- Magic numbers -----------------------------------------------------*/
66
67 #define SHA256_BUFSZ 64
68 #define SHA256_HASHSZ 32
69 #define SHA256_STATESZ 32
70
71 /*----- Data structures ---------------------------------------------------*/
72
73 typedef struct sha256_ctx {
74 uint32 a, b, c, d, e, f, g, h; /* Chaining variables */
75 uint32 nl, nh; /* Byte count so far */
76 unsigned off; /* Offset into buffer */
77 octet buf[SHA256_BUFSZ]; /* Accumulation buffer */
78 } sha256_ctx;
79
80 /*----- Functions provided ------------------------------------------------*/
81
82 /* --- @sha256_compress@ --- *
83 *
84 * Arguments: @sha256_ctx *ctx@ = pointer to context block
85 * @const void *sbuf@ = pointer to buffer of appropriate size
86 *
87 * Returns: ---
88 *
89 * Use: SHA-256 compression function.
90 */
91
92 extern void sha256_compress(sha256_ctx */*ctx*/, const void */*sbuf*/);
93
94 /* --- @sha256_init@ --- *
95 *
96 * Arguments: @sha256_ctx *ctx@ = pointer to context block to initialize
97 *
98 * Returns: ---
99 *
100 * Use: Initializes a context block ready for hashing.
101 */
102
103 extern void sha256_init(sha256_ctx */*ctx*/);
104
105 /* --- @sha256_set@ --- *
106 *
107 * Arguments: @sha256_ctx *ctx@ = pointer to context block
108 * @const void *buf@ = pointer to state buffer
109 * @unsigned long count@ = current count of bytes processed
110 *
111 * Returns: ---
112 *
113 * Use: Initializes a context block from a given state. This is
114 * useful in cases where the initial hash state is meant to be
115 * secret, e.g., for NMAC and HMAC support.
116 */
117
118 extern void sha256_set(sha256_ctx */*ctx*/, const void */*buf*/,
119 unsigned long /*count*/);
120
121 /* --- @sha256_hash@ --- *
122 *
123 * Arguments: @sha256_ctx *ctx@ = pointer to context block
124 * @const void *buf@ = buffer of data to hash
125 * @size_t sz@ = size of buffer to hash
126 *
127 * Returns: ---
128 *
129 * Use: Hashes a buffer of data. The buffer may be of any size and
130 * alignment.
131 */
132
133 extern void sha256_hash(sha256_ctx */*ctx*/,
134 const void */*buf*/, size_t /*sz*/);
135
136 /* --- @sha256_done@ --- *
137 *
138 * Arguments: @sha256_ctx *ctx@ = pointer to context block
139 * @void *hash@ = pointer to output buffer
140 *
141 * Returns: ---
142 *
143 * Use: Returns the hash of the data read so far.
144 */
145
146 extern void sha256_done(sha256_ctx */*ctx*/, void */*hash*/);
147
148 /* --- @sha256_state@ --- *
149 *
150 * Arguments: @sha256_ctx *ctx@ = pointer to context
151 * @void *state@ = pointer to buffer for current state
152 *
153 * Returns: Number of bytes written to the hash function so far.
154 *
155 * Use: Returns the current state of the hash function such that
156 * it can be passed to @sha256_set@.
157 */
158
159 extern unsigned long sha256_state(sha256_ctx */*ctx*/, void */*state*/);
160
161 /*----- Generic hash interface --------------------------------------------*/
162
163 extern const gchash sha256;
164
165 /*----- That's all, folks -------------------------------------------------*/
166
167 #ifdef __cplusplus
168 }
169 #endif
170
171 #endif