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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: dsa.h,v 1.5 2000/06/17 10:53:42 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 1.5 2000/06/17 10:53:42 mdw |
34 | * Minor changes for key fetching. Typesetting fixes. |
35 | * |
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36 | * Revision 1.4 1999/12/22 15:52:44 mdw |
37 | * Reworking for new prime-search system. |
38 | * |
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39 | * Revision 1.3 1999/12/10 23:29:48 mdw |
40 | * Change header file guard names. |
41 | * |
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42 | * Revision 1.2 1999/11/20 22:23:48 mdw |
43 | * Allow event handler to abort the search process. |
44 | * |
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45 | * Revision 1.1 1999/11/19 19:28:00 mdw |
46 | * Implementation of the Digital Signature Algorithm. |
47 | * |
48 | */ |
49 | |
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50 | #ifndef CATACOMB_DSA_H |
51 | #define CATACOMB_DSA_H |
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52 | |
53 | #ifdef __cplusplus |
54 | extern "C" { |
55 | #endif |
56 | |
57 | /*----- Notes on the Digital Signature Algorithm --------------------------* |
58 | * |
59 | * The Digital Signature Algorithm was designed by the NSA for US Government |
60 | * use. It's defined in FIPS 186-1. Whether it's covered by patents is |
61 | * under dispute, although it looks relatively clear. It produces compact |
62 | * signatures, and is relatively easy to compute. It seems strong, if |
63 | * appropriate parameters are chosen. |
64 | */ |
65 | |
66 | /*----- Header files ------------------------------------------------------*/ |
67 | |
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68 | #ifndef CATACOMB_KEY_H |
69 | # include "key.h" |
70 | #endif |
71 | |
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72 | #ifndef CATACOMB_MP_H |
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73 | # include "mp.h" |
74 | #endif |
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75 | |
76 | #ifndef CATACOMB_PGEN_H |
77 | # include "pgen.h" |
78 | #endif |
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79 | |
80 | /*----- Data structures ---------------------------------------------------*/ |
81 | |
82 | /* --- DSA parameter structure --- * |
83 | * |
84 | * These parameters can, and probably should, be shared among a group of |
85 | * users. |
86 | */ |
87 | |
88 | typedef struct dsa_param { |
89 | mp *p, *q; /* Prime numbers %$p$% and %$q$% */ |
90 | mp *g; /* Generates order-%$q$% subgroup */ |
91 | } dsa_param; |
92 | |
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93 | typedef struct dsa_pub { |
94 | dsa_param dp; /* Shared parameters */ |
95 | mp *y; /* Public key */ |
96 | } dsa_pub; |
97 | |
98 | typedef struct dsa_priv { |
99 | dsa_param dp; /* Shared parameters */ |
100 | mp *x; /* Private key */ |
101 | mp *y; /* %$y \equiv g^x \pmod{p}$% */ |
102 | } dsa_priv; |
103 | |
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104 | /* --- DSA signature structure --- * |
105 | * |
106 | * This is the recommended structure for a DSA signature. The actual signing |
107 | * function can cope with arbitrary-sized objects given appropriate |
108 | * parameters, however. |
109 | */ |
110 | |
111 | #define DSA_SIGLEN 20 |
112 | |
113 | typedef struct dsa_sig { |
114 | octet r[DSA_SIGLEN]; /* 160-bit @r@ value */ |
115 | octet s[DSA_SIGLEN]; /* 160-bit @s@ value */ |
116 | } dsa_sig; |
117 | |
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118 | /*----- Key fetching ------------------------------------------------------*/ |
119 | |
120 | extern const key_fetchdef dsa_paramfetch[]; |
121 | #define DSA_PARAMFETCHSZ 5 |
122 | |
123 | extern const key_fetchdef dsa_pubfetch[]; |
124 | #define DSA_PUBFETCHSZ 6 |
125 | |
126 | extern const key_fetchdef dsa_privfetch[]; |
127 | #define DSA_PRIVFETCHSZ 9 |
128 | |
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129 | /*----- DSA stepper -------------------------------------------------------*/ |
130 | |
131 | typedef struct dsa_stepctx { |
132 | |
133 | /* --- To be initialized by the client --- */ |
134 | |
135 | grand *r; /* Random number generator */ |
136 | mp *q; /* Force @p@ to be a multiple */ |
137 | size_t bits; /* Number of bits in the result */ |
138 | unsigned or; /* OR mask for low order bits */ |
139 | } dsa_stepctx; |
140 | |
141 | /* --- @dsa_step@ --- * |
142 | * |
143 | * The stepper chooses random integers, ensures that they are a multiple of |
144 | * @q@ (if specified), sets the low-order bits, and then tests for |
145 | * divisibility by small primes. |
146 | */ |
147 | |
148 | extern int dsa_step(int /*rq*/, pgen_event */*ev*/, void */*p*/); |
149 | |
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150 | /*----- Functions provided ------------------------------------------------*/ |
151 | |
152 | /* --- @dsa_seed@ --- * |
153 | * |
154 | * Arguments: @dsa_param *dp@ = where to store parameters |
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155 | * @unsigned ql@ = length of @q@ in bits |
156 | * @unsigned pl@ = length of @p@ in bits |
157 | * @unsigned steps@ = number of steps to find @q@ |
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158 | * @const void *k@ = pointer to key material |
159 | * @size_t sz@ = size of key material |
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160 | * @pgen_proc *event@ = event handler function |
161 | * @void *ectx@ = argument for event handler |
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162 | * |
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163 | * Returns: @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise. |
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164 | * |
165 | * Use: Generates the DSA shared parameters from a given seed value. |
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166 | * This can take quite a long time. |
167 | * |
168 | * The algorithm used is a compatible extension of the method |
169 | * described in the DSA standard, FIPS 186. The standard |
170 | * requires that %$q$% be 160 bits in size (i.e., @ql == 160@) |
171 | * and that the length of %$p$% be %$L = 512 + 64l$% for some |
172 | * %$l$%. Neither limitation applies to this implementation. |
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173 | */ |
174 | |
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175 | extern int dsa_seed(dsa_param */*dp*/, unsigned /*ql*/, unsigned /*pl*/, |
176 | unsigned /*steps*/, const void */*k*/, size_t /*sz*/, |
177 | pgen_proc */*event*/, void */*ectx*/); |
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178 | |
179 | /* --- @dsa_mksig@ --- * |
180 | * |
181 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
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182 | * @mp *a@ = secret signing key |
183 | * @mp *m@ = message to be signed |
184 | * @mp *k@ = random data |
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185 | * @mp **rr, **ss@ = where to put output parameters |
186 | * |
187 | * Returns: --- |
188 | * |
189 | * Use: Computes a DSA signature of a message. |
190 | */ |
191 | |
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192 | extern void dsa_mksig(const dsa_param */*dp*/, mp */*a*/, |
193 | mp */*m*/, mp */*k*/, |
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194 | mp **/*rr*/, mp **/*ss*/); |
195 | |
196 | /* --- @dsa_sign@ --- * |
197 | * |
198 | * Arguments: @dsa_param *dp@ = pointer to DSA parameters |
199 | * @mp *a@ = pointer to secret signing key |
200 | * @const void *m@ = pointer to message |
201 | * @size_t msz@ = size of the message |
202 | * @const void *k@ = secret random data for securing signature |
203 | * @size_t ksz@ = size of secret data |
204 | * @void *r@ = pointer to output space for @r@ |
205 | * @size_t rsz@ = size of output space for @r@ |
206 | * @void *s@ = pointer to output space for @s@ |
207 | * @size_t ssz@ = size of output space for @s@ |
208 | * |
209 | * Returns: --- |
210 | * |
211 | * Use: Signs a message, storing the results in a big-endian binary |
212 | * form. |
213 | */ |
214 | |
215 | extern void dsa_sign(dsa_param */*dp*/, mp */*a*/, |
216 | const void */*m*/, size_t /*msz*/, |
217 | const void */*k*/, size_t /*ksz*/, |
218 | void */*r*/, size_t /*rsz*/, |
219 | void */*s*/, size_t /*ssz*/); |
220 | |
221 | /* --- @dsa_vrfy@ --- * |
222 | * |
223 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
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224 | * @mp *y@ = public verification key |
225 | * @mp *m@ = message which was signed |
226 | * @mp *r, *s@ = the signature |
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227 | * |
228 | * Returns: Zero if the signature is a forgery, nonzero if it's valid. |
229 | * |
230 | * Use: Verifies a DSA digital signature. |
231 | */ |
232 | |
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233 | extern int dsa_vrfy(const dsa_param */*dp*/, mp */*y*/, |
234 | mp */*m*/, mp */*r*/, mp */*s*/); |
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235 | |
236 | /* --- @dsa_verify@ --- * |
237 | * |
238 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
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239 | * @mp *y@ = public verification key |
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240 | * @const void *m@ = pointer to message block |
241 | * @size_t msz@ = size of message block |
242 | * @const void *r@ = pointer to @r@ signature half |
243 | * @size_t rsz@ = size of @r@ |
244 | * @const void *s@ = pointer to @s@ signature half |
245 | * @size_t ssz@ = size of @s@ |
246 | * |
247 | * Returns: Zero if the signature is a forgery, nonzero if it's valid. |
248 | * |
249 | * Use: Verifies a DSA digital signature. |
250 | */ |
251 | |
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252 | extern int dsa_verify(const dsa_param */*dp*/, mp */*y*/, |
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253 | const void */*m*/, size_t /*msz*/, |
254 | const void */*r*/, size_t /*rsz*/, |
255 | const void */*s*/, size_t /*ssz*/); |
256 | |
257 | /*----- That's all, folks -------------------------------------------------*/ |
258 | |
259 | #ifdef __cplusplus |
260 | } |
261 | #endif |
262 | |
263 | #endif |