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1 | /* -*-c-*- |
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2 | * |
3 | * Random number generator for DSA |
4 | * |
5 | * (c) 1999 Straylight/Edgeware |
6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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9 | * |
10 | * This file is part of Catacomb. |
11 | * |
12 | * Catacomb is free software; you can redistribute it and/or modify |
13 | * it under the terms of the GNU Library General Public License as |
14 | * published by the Free Software Foundation; either version 2 of the |
15 | * License, or (at your option) any later version. |
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16 | * |
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17 | * Catacomb is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU Library General Public License for more details. |
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21 | * |
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22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with Catacomb; if not, write to the Free |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
25 | * MA 02111-1307, USA. |
26 | */ |
27 | |
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28 | #ifndef CATACOMB_DSARAND_H |
29 | #define CATACOMB_DSARAND_H |
30 | |
31 | #ifdef __cplusplus |
32 | extern "C" { |
33 | #endif |
34 | |
35 | /*----- Header files ------------------------------------------------------*/ |
36 | |
37 | #include <mLib/bits.h> |
38 | |
39 | #ifndef CATACOMB_GRAND_H |
40 | # include "grand.h" |
41 | #endif |
42 | |
43 | #ifndef CATACOMB_SHA_H |
44 | # include "sha.h" |
45 | #endif |
46 | |
47 | /*----- Data structures ---------------------------------------------------*/ |
48 | |
49 | typedef struct dsarand { |
50 | octet *p; /* Pointer to seed (modified) */ |
51 | size_t sz; /* Size of the seed buffer */ |
52 | unsigned passes; /* Number of passes to make */ |
53 | } dsarand; |
54 | |
55 | /*----- Functions provided ------------------------------------------------*/ |
56 | |
57 | /* --- @dsarand_init@ --- * |
58 | * |
59 | * Arguments: @dsarand *d@ = pointer to context |
60 | * @const void *p@ = pointer to seed buffer |
61 | * @size_t sz@ = size of the buffer |
62 | * |
63 | * Returns: --- |
64 | * |
65 | * Use: Initializes a DSA random number generator. |
66 | */ |
67 | |
68 | extern void dsarand_init(dsarand */*d*/, const void */*p*/, size_t /*sz*/); |
69 | |
70 | /* --- @dsarand_reseed@ --- * |
71 | * |
72 | * Arguments: @dsarand *d@ = pointer to context |
73 | * @const void *p@ = pointer to seed buffer |
74 | * @size_t sz@ = size of the buffer |
75 | * |
76 | * Returns: --- |
77 | * |
78 | * Use: Initializes a DSA random number generator. |
79 | */ |
80 | |
81 | extern void dsarand_reseed(dsarand */*d*/, const void */*p*/, size_t /*sz*/); |
82 | |
83 | /* --- @dsarand_destroy@ --- * |
84 | * |
85 | * Arguments: @dsarand *d@ = pointer to context |
86 | * |
87 | * Returns: --- |
88 | * |
89 | * Use: Disposes of a DSA random number generation context. |
90 | */ |
91 | |
92 | extern void dsarand_destroy(dsarand */*d*/); |
93 | |
94 | /* --- @dsarand_fill@ --- * |
95 | * |
96 | * Arguments: @dsarand *d@ = pointer to context |
97 | * @void *p@ = pointer to output buffer |
98 | * @size_t sz@ = size of output buffer |
99 | * |
100 | * Returns: --- |
101 | * |
102 | * Use: Fills an output buffer with pseudorandom data. |
103 | * |
104 | * Let %$p$% be the numerical value of the input buffer, and let |
105 | * %$b$% be the number of bytes required. Let |
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106 | * %$z = \lceil b / 20 \rceil$% be the number of SHA outputs |
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107 | * required. Then the output of pass %$n$% is |
108 | * |
109 | * %$P_n = \sum_{0 \le i < z} 2^{160i} SHA(p + nz + i)$% |
110 | * %${} \bmod 2^{8b}$% |
111 | * |
112 | * and the actual result in the output buffer is the XOR of all |
113 | * of the output passes. |
114 | * |
115 | * The DSA procedure for choosing @q@ involves two passes with |
116 | * %$z = 1$%; the procedure for choosing @p@ involves one pass |
117 | * with larger %$z$%. This generalization of the DSA generation |
118 | * procedure is my own invention but it seems relatively sound. |
119 | */ |
120 | |
121 | extern void dsarand_fill(dsarand */*d*/, void */*p*/, size_t /*sz*/); |
122 | |
123 | /*----- Generic pseudorandom-number generator interface -------------------*/ |
124 | |
125 | /* --- Miscellaneous operations --- */ |
126 | |
127 | enum { |
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128 | DSARAND_PASSES = GRAND_SPECIFIC('D'), /* @unsigned n@ */ |
129 | DSARAND_SEEDSZ, /* No args */ |
130 | DSARAND_GETSEED /* @void *buf@ */ |
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131 | }; |
132 | |
133 | /* --- @dsarand_create@ --- * |
134 | * |
135 | * Arguments: @const void *p@ = pointer to seed buffer |
136 | * @size_t sz@ = size of seed buffer |
137 | * |
138 | * Returns: Pointer to a generic generator. |
139 | * |
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140 | * Use: Constructs a generic generator interface to a DSA generator. |
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141 | */ |
142 | |
143 | extern grand *dsarand_create(const void */*p*/, size_t /*sz*/); |
144 | |
145 | /*----- That's all, folks -------------------------------------------------*/ |
146 | |
147 | #ifdef __cplusplus |
148 | } |
149 | #endif |
150 | |
151 | #endif |