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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: dsa.h,v 1.2 1999/11/20 22:23:48 mdw Exp $ |
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4 | * |
5 | * Digital Signature Algorithm |
6 | * |
7 | * (c) 1999 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: dsa.h,v $ |
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33 | * Revision 1.2 1999/11/20 22:23:48 mdw |
34 | * Allow event handler to abort the search process. |
35 | * |
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36 | * Revision 1.1 1999/11/19 19:28:00 mdw |
37 | * Implementation of the Digital Signature Algorithm. |
38 | * |
39 | */ |
40 | |
41 | #ifndef DSA_H |
42 | #define DSA_H |
43 | |
44 | #ifdef __cplusplus |
45 | extern "C" { |
46 | #endif |
47 | |
48 | /*----- Notes on the Digital Signature Algorithm --------------------------* |
49 | * |
50 | * The Digital Signature Algorithm was designed by the NSA for US Government |
51 | * use. It's defined in FIPS 186-1. Whether it's covered by patents is |
52 | * under dispute, although it looks relatively clear. It produces compact |
53 | * signatures, and is relatively easy to compute. It seems strong, if |
54 | * appropriate parameters are chosen. |
55 | */ |
56 | |
57 | /*----- Header files ------------------------------------------------------*/ |
58 | |
59 | #ifndef MP_H |
60 | # include "mp.h" |
61 | #endif |
62 | |
63 | /*----- Event codes -------------------------------------------------------*/ |
64 | |
65 | enum { |
66 | DSAEV_OK, /* Everything is fine */ |
67 | |
68 | DSAEV_FAILQ, /* @q@ failed primality test */ |
69 | DSAEV_PASSQ, /* @q@ passeed one iteration */ |
70 | DSAEV_GOODQ, /* Found good prime @q@ */ |
71 | |
72 | DSAEV_TRYP, /* Try prospective @p@ */ |
73 | DSAEV_FAILP, /* @p@ failed primality test */ |
74 | DSAEV_PASSP, /* @p@ passed one iteration */ |
75 | DSAEV_GOODP, /* @p@ accepted as being prime */ |
76 | |
77 | DSAEV_TRYH, /* Try prospective @h@ */ |
78 | DSAEV_FAILH, /* @h@ failed */ |
79 | DSAEV_GOODG /* @g@ accepted as a generator */ |
80 | }; |
81 | |
82 | /*----- Data structures ---------------------------------------------------*/ |
83 | |
84 | /* --- DSA parameter structure --- * |
85 | * |
86 | * These parameters can, and probably should, be shared among a group of |
87 | * users. |
88 | */ |
89 | |
90 | typedef struct dsa_param { |
91 | mp *p, *q; /* Prime numbers %$p$% and %$q$% */ |
92 | mp *g; /* Generates order-%$q$% subgroup */ |
93 | } dsa_param; |
94 | |
95 | /* --- DSA signature structure --- * |
96 | * |
97 | * This is the recommended structure for a DSA signature. The actual signing |
98 | * function can cope with arbitrary-sized objects given appropriate |
99 | * parameters, however. |
100 | */ |
101 | |
102 | #define DSA_SIGLEN 20 |
103 | |
104 | typedef struct dsa_sig { |
105 | octet r[DSA_SIGLEN]; /* 160-bit @r@ value */ |
106 | octet s[DSA_SIGLEN]; /* 160-bit @s@ value */ |
107 | } dsa_sig; |
108 | |
109 | /*----- Functions provided ------------------------------------------------*/ |
110 | |
111 | /* --- @dsa_seed@ --- * |
112 | * |
113 | * Arguments: @dsa_param *dp@ = where to store parameters |
114 | * @unsigned l@ = bitlength of @p@ in bits |
115 | * @const void *k@ = pointer to key material |
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116 | * @int (*proc)(int ev, mp *m, void *p)@ = event procedure |
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117 | * @size_t sz@ = size of key material |
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118 | * |
119 | * Returns: Zero if all went well, nonzero if key material was |
120 | * unsuitable (one of the @DSAEV@ codes). |
121 | * |
122 | * Use: Generates the DSA shared parameters from a given seed value. |
123 | * This can take quite a long time. The size of @p@ in bits is |
124 | * %$l = 512 + 64l'$%. The DSA standard, FIPS 186, only allows |
125 | * %$0 \le l' \le 8$%. This implementation has no such limit, |
126 | * although @l@ must be a multiple of 8. |
127 | * |
128 | * The event procedure is informed of various happenings during |
129 | * generation. It is passed an event code describing what |
130 | * happened, and a multiprecision number which pertains to the |
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131 | * event code. It may abort the search at any time by returning |
132 | * a nonzero value, which is returned as the result of the |
133 | * function. |
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134 | */ |
135 | |
136 | extern int dsa_seed(dsa_param */*dp*/, unsigned /*l*/, |
137 | const void */*k*/, size_t /*sz*/, |
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138 | int (*proc)(int /*ev*/, mp */*m*/, void */*p*/), |
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139 | void */*p*/); |
140 | |
141 | /* --- @dsa_mksig@ --- * |
142 | * |
143 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
144 | * @const mp *a@ = secret signing key |
145 | * @const mp *m@ = message to be signed |
146 | * @const mp *k@ = random data |
147 | * @mp **rr, **ss@ = where to put output parameters |
148 | * |
149 | * Returns: --- |
150 | * |
151 | * Use: Computes a DSA signature of a message. |
152 | */ |
153 | |
154 | extern void dsa_mksig(const dsa_param */*dp*/, const mp */*a*/, |
155 | const mp */*m*/, const mp */*k*/, |
156 | mp **/*rr*/, mp **/*ss*/); |
157 | |
158 | /* --- @dsa_sign@ --- * |
159 | * |
160 | * Arguments: @dsa_param *dp@ = pointer to DSA parameters |
161 | * @mp *a@ = pointer to secret signing key |
162 | * @const void *m@ = pointer to message |
163 | * @size_t msz@ = size of the message |
164 | * @const void *k@ = secret random data for securing signature |
165 | * @size_t ksz@ = size of secret data |
166 | * @void *r@ = pointer to output space for @r@ |
167 | * @size_t rsz@ = size of output space for @r@ |
168 | * @void *s@ = pointer to output space for @s@ |
169 | * @size_t ssz@ = size of output space for @s@ |
170 | * |
171 | * Returns: --- |
172 | * |
173 | * Use: Signs a message, storing the results in a big-endian binary |
174 | * form. |
175 | */ |
176 | |
177 | extern void dsa_sign(dsa_param */*dp*/, mp */*a*/, |
178 | const void */*m*/, size_t /*msz*/, |
179 | const void */*k*/, size_t /*ksz*/, |
180 | void */*r*/, size_t /*rsz*/, |
181 | void */*s*/, size_t /*ssz*/); |
182 | |
183 | /* --- @dsa_vrfy@ --- * |
184 | * |
185 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
186 | * @const mp *y@ = public verification key |
187 | * @const mp *m@ = message which was signed |
188 | * @const mp *r, *s@ = the signature |
189 | * |
190 | * Returns: Zero if the signature is a forgery, nonzero if it's valid. |
191 | * |
192 | * Use: Verifies a DSA digital signature. |
193 | */ |
194 | |
195 | extern int dsa_vrfy(const dsa_param */*dp*/, const mp */*y*/, |
196 | const mp */*m*/, const mp */*r*/, const mp */*s*/); |
197 | |
198 | /* --- @dsa_verify@ --- * |
199 | * |
200 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
201 | * @const mp *y@ = public verification key |
202 | * @const void *m@ = pointer to message block |
203 | * @size_t msz@ = size of message block |
204 | * @const void *r@ = pointer to @r@ signature half |
205 | * @size_t rsz@ = size of @r@ |
206 | * @const void *s@ = pointer to @s@ signature half |
207 | * @size_t ssz@ = size of @s@ |
208 | * |
209 | * Returns: Zero if the signature is a forgery, nonzero if it's valid. |
210 | * |
211 | * Use: Verifies a DSA digital signature. |
212 | */ |
213 | |
214 | extern int dsa_verify(const dsa_param */*dp*/, const mp */*y*/, |
215 | const void */*m*/, size_t /*msz*/, |
216 | const void */*r*/, size_t /*rsz*/, |
217 | const void */*s*/, size_t /*ssz*/); |
218 | |
219 | /*----- That's all, folks -------------------------------------------------*/ |
220 | |
221 | #ifdef __cplusplus |
222 | } |
223 | #endif |
224 | |
225 | #endif |