ct.c, ct.h: New constant-time operations.
[u/mdw/catacomb] / sha256.h
1 /* -*-c-*-
2 *
3 * $Id$
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 /*----- Notes on the SHA-256 hash function --------------------------------*
31 *
32 * SHA-1 (Secure Hash Algorithm) was designed by the NSA, for use with the
33 * Digital Signature Algorithm. This is an evolution with a larger output
34 * size, intended to provide security commensurate with 128-bit AES. At the
35 * time of writing, SHA-256 is very new, and can't be trusted too far.
36 */
37
38 #ifndef CATACOMB_SHA256_H
39 #define CATACOMB_SHA256_H
40 #define CATACOMB_SHA224_H
41
42 #ifdef __cplusplus
43 extern "C" {
44 #endif
45
46 /*----- Header files ------------------------------------------------------*/
47
48 #include <mLib/bits.h>
49
50 #ifndef CATACOMB_GHASH_H
51 # include "ghash.h"
52 #endif
53
54 /*----- Magic numbers -----------------------------------------------------*/
55
56 #define SHA256_BUFSZ 64
57 #define SHA256_HASHSZ 32
58 #define SHA256_STATESZ 32
59
60 #define SHA224_BUFSZ 64
61 #define SHA224_HASHSZ 28
62 #define SHA224_STATESZ 32
63
64 /*----- Data structures ---------------------------------------------------*/
65
66 typedef struct sha256_ctx {
67 uint32 a, b, c, d, e, f, g, h; /* Chaining variables */
68 uint32 nl, nh; /* Byte count so far */
69 unsigned off; /* Offset into buffer */
70 octet buf[SHA256_BUFSZ]; /* Accumulation buffer */
71 } sha256_ctx, sha224_ctx;
72
73 /*----- Functions provided ------------------------------------------------*/
74
75 /* --- @sha256_compress@, @sha224_compress@ --- *
76 *
77 * Arguments: @sha256_ctx *ctx@ = pointer to context block
78 * @const void *sbuf@ = pointer to buffer of appropriate size
79 *
80 * Returns: ---
81 *
82 * Use: SHA-256 compression function.
83 */
84
85 extern void sha256_compress(sha256_ctx */*ctx*/, const void */*sbuf*/);
86 #define sha224_compress sha256_compress
87
88 /* --- @sha256_init@, @sha224_init@ --- *
89 *
90 * Arguments: @sha256_ctx *ctx@ = pointer to context block to initialize
91 *
92 * Returns: ---
93 *
94 * Use: Initializes a context block ready for hashing.
95 */
96
97 extern void sha256_init(sha256_ctx */*ctx*/);
98 extern void sha224_init(sha256_ctx */*ctx*/);
99
100 /* --- @sha256_set@, @sha224_set@ --- *
101 *
102 * Arguments: @sha256_ctx *ctx@ = pointer to context block
103 * @const void *buf@ = pointer to state buffer
104 * @unsigned long count@ = current count of bytes processed
105 *
106 * Returns: ---
107 *
108 * Use: Initializes a context block from a given state. This is
109 * useful in cases where the initial hash state is meant to be
110 * secret, e.g., for NMAC and HMAC support.
111 */
112
113 extern void sha256_set(sha256_ctx */*ctx*/, const void */*buf*/,
114 unsigned long /*count*/);
115 #define sha224_set sha256_set
116
117 /* --- @sha256_hash@, @sha224_hash@ --- *
118 *
119 * Arguments: @sha256_ctx *ctx@ = pointer to context block
120 * @const void *buf@ = buffer of data to hash
121 * @size_t sz@ = size of buffer to hash
122 *
123 * Returns: ---
124 *
125 * Use: Hashes a buffer of data. The buffer may be of any size and
126 * alignment.
127 */
128
129 extern void sha256_hash(sha256_ctx */*ctx*/,
130 const void */*buf*/, size_t /*sz*/);
131 #define sha224_hash sha256_hash
132
133 /* --- @sha256_done@, @sha224_done@ --- *
134 *
135 * Arguments: @sha256_ctx *ctx@ = pointer to context block
136 * @void *hash@ = pointer to output buffer
137 *
138 * Returns: ---
139 *
140 * Use: Returns the hash of the data read so far.
141 */
142
143 extern void sha256_done(sha256_ctx */*ctx*/, void */*hash*/);
144 extern void sha224_done(sha256_ctx */*ctx*/, void */*hash*/);
145
146 /* --- @sha256_state@, @sha224_state@ --- *
147 *
148 * Arguments: @sha256_ctx *ctx@ = pointer to context
149 * @void *state@ = pointer to buffer for current state
150 *
151 * Returns: Number of bytes written to the hash function so far.
152 *
153 * Use: Returns the current state of the hash function such that
154 * it can be passed to @sha256_set@.
155 */
156
157 extern unsigned long sha256_state(sha256_ctx */*ctx*/, void */*state*/);
158 #define sha224_state sha256_state
159
160 /*----- Generic hash interface --------------------------------------------*/
161
162 extern const gchash sha256;
163 extern const gchash sha224;
164
165 /*----- That's all, folks -------------------------------------------------*/
166
167 #ifdef __cplusplus
168 }
169 #endif
170
171 #endif