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1/* -*-c-*-
2 *
6b2d9d76 3 * $Id: dsarand.h,v 1.2 2000/07/02 15:21:20 mdw Exp $
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4 *
5 * Random number generator for DSA
6 *
7 * (c) 1999 Straylight/Edgeware
8 * (c) 2000 Mark Wooding
9 */
10
11/*----- Licensing notice --------------------------------------------------*
12 *
13 * Copyright (c) 2000 Mark Wooding
14 * All rights reserved.
15 *
16 * Redistribution and use in source and binary forms, with or without
17 * modification, are permitted provided that the following conditions are
18 * met:
19 *
20 * 1. Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 *
23 * 2, Redistributions in binary form must reproduce the above copyright
24 * notice, this list of conditions and the following disclaimer in the
25 * documentation and/or other materials provided with the distribution.
26 *
27 * 3. The name of the authors may not be used to endorse or promote
28 * products derived from this software without specific prior written
29 * permission.
30 *
31 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
32 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
33 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
6b2d9d76 34 * NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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35 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
36 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
37 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
38 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
39 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
40 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
41 * POSSIBILITY OF SUCH DAMAGE.
42 *
43 * Instead of accepting the above terms, you may redistribute and/or modify
44 * this software under the terms of either the GNU General Public License,
45 * or the GNU Library General Public License, published by the Free
46 * Software Foundation; either version 2 of the License, or (at your
47 * option) any later version.
48 */
49
50/*----- Revision history --------------------------------------------------*
51 *
52 * $Log: dsarand.h,v $
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53 * Revision 1.2 2000/07/02 15:21:20 mdw
54 * Fix licence text.
55 *
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56 * Revision 1.1 2000/05/21 11:28:30 mdw
57 * Initial check-in.
58 *
59 * --- Past lives (Catacomb) --- *
60 *
61 * Revision 1.1 1999/12/22 15:53:12 mdw
62 * Random number generator for finding DSA parameters.
63 *
64 */
65
66#ifndef DSARAND_H
67#define DSARAND_H
68
69#ifdef __cplusplus
70 extern "C" {
71#endif
72
73/*----- Header files ------------------------------------------------------*/
74
75#ifndef BITS_H
76# include "bits.h"
77#endif
78
79#ifndef SHA_H
80# include "sha.h"
81#endif
82
83/*----- Data structures ---------------------------------------------------*/
84
85typedef struct dsarand {
86 octet *p; /* Pointer to seed (modified) */
87 size_t sz; /* Size of the seed buffer */
88 unsigned passes; /* Number of passes to make */
89} dsarand;
90
91/*----- Functions provided ------------------------------------------------*/
92
93/* --- @dsarand_init@ --- *
94 *
95 * Arguments: @dsarand *d@ = pointer to context
96 * @const void *p@ = pointer to seed buffer
97 * @size_t sz@ = size of the buffer
98 *
99 * Returns: ---
100 *
101 * Use: Initializes a DSA random number generator.
102 */
103
104extern void dsarand_init(dsarand */*d*/, const void */*p*/, size_t /*sz*/);
105
106/* --- @dsarand_reseed@ --- *
107 *
108 * Arguments: @dsarand *d@ = pointer to context
109 * @const void *p@ = pointer to seed buffer
110 * @size_t sz@ = size of the buffer
111 *
112 * Returns: ---
113 *
114 * Use: Initializes a DSA random number generator.
115 */
116
117extern void dsarand_reseed(dsarand */*d*/, const void */*p*/, size_t /*sz*/);
118
119/* --- @dsarand_destroy@ --- *
120 *
121 * Arguments: @dsarand *d@ = pointer to context
122 *
123 * Returns: ---
124 *
125 * Use: Disposes of a DSA random number generation context.
126 */
127
128extern void dsarand_destroy(dsarand */*d*/);
129
130/* --- @dsarand_fill@ --- *
131 *
132 * Arguments: @dsarand *d@ = pointer to context
133 * @void *p@ = pointer to output buffer
134 * @size_t sz@ = size of output buffer
135 *
136 * Returns: ---
137 *
138 * Use: Fills an output buffer with pseudorandom data.
139 *
140 * Let %$p$% be the numerical value of the input buffer, and let
141 * %$b$% be the number of bytes required. Let
142 * %$z = \lceil b / 20 \rceil$% be the number of SHA outputs
143 * required. Then the output of pass %$n$% is
144 *
145 * %$P_n = \sum_{0 \le i < z} 2^{160i} SHA(p + nz + i)$%
146 * %${} \bmod 2^{8b}$%
147 *
148 * and the actual result in the output buffer is the XOR of all
149 * of the output passes.
150 *
151 * The DSA procedure for choosing @q@ involves two passes with
152 * %$z = 1$%; the procedure for choosing @p@ involves one pass
153 * with larger %$z$%. This generalization of the DSA generation
154 * procedure is my own invention but it seems relatively sound.
155 */
156
157extern void dsarand_fill(dsarand */*d*/, void */*p*/, size_t /*sz*/);
158
159/*----- That's all, folks -------------------------------------------------*/
160
161#ifdef __cplusplus
162 }
163#endif
164
165#endif