8b810a45 |
1 | /* -*-c-*- |
2 | * |
b04a7659 |
3 | * $Id: dsa.h,v 1.4 1999/12/22 15:52:44 mdw Exp $ |
8b810a45 |
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 $ |
b04a7659 |
33 | * Revision 1.4 1999/12/22 15:52:44 mdw |
34 | * Reworking for new prime-search system. |
35 | * |
b3f05084 |
36 | * Revision 1.3 1999/12/10 23:29:48 mdw |
37 | * Change header file guard names. |
38 | * |
987bb691 |
39 | * Revision 1.2 1999/11/20 22:23:48 mdw |
40 | * Allow event handler to abort the search process. |
41 | * |
8b810a45 |
42 | * Revision 1.1 1999/11/19 19:28:00 mdw |
43 | * Implementation of the Digital Signature Algorithm. |
44 | * |
45 | */ |
46 | |
b3f05084 |
47 | #ifndef CATACOMB_DSA_H |
48 | #define CATACOMB_DSA_H |
8b810a45 |
49 | |
50 | #ifdef __cplusplus |
51 | extern "C" { |
52 | #endif |
53 | |
54 | /*----- Notes on the Digital Signature Algorithm --------------------------* |
55 | * |
56 | * The Digital Signature Algorithm was designed by the NSA for US Government |
57 | * use. It's defined in FIPS 186-1. Whether it's covered by patents is |
58 | * under dispute, although it looks relatively clear. It produces compact |
59 | * signatures, and is relatively easy to compute. It seems strong, if |
60 | * appropriate parameters are chosen. |
61 | */ |
62 | |
63 | /*----- Header files ------------------------------------------------------*/ |
64 | |
b3f05084 |
65 | #ifndef CATACOMB_MP_H |
8b810a45 |
66 | # include "mp.h" |
67 | #endif |
b04a7659 |
68 | |
69 | #ifndef CATACOMB_PGEN_H |
70 | # include "pgen.h" |
71 | #endif |
8b810a45 |
72 | |
73 | /*----- Data structures ---------------------------------------------------*/ |
74 | |
75 | /* --- DSA parameter structure --- * |
76 | * |
77 | * These parameters can, and probably should, be shared among a group of |
78 | * users. |
79 | */ |
80 | |
81 | typedef struct dsa_param { |
82 | mp *p, *q; /* Prime numbers %$p$% and %$q$% */ |
83 | mp *g; /* Generates order-%$q$% subgroup */ |
84 | } dsa_param; |
85 | |
86 | /* --- DSA signature structure --- * |
87 | * |
88 | * This is the recommended structure for a DSA signature. The actual signing |
89 | * function can cope with arbitrary-sized objects given appropriate |
90 | * parameters, however. |
91 | */ |
92 | |
93 | #define DSA_SIGLEN 20 |
94 | |
95 | typedef struct dsa_sig { |
96 | octet r[DSA_SIGLEN]; /* 160-bit @r@ value */ |
97 | octet s[DSA_SIGLEN]; /* 160-bit @s@ value */ |
98 | } dsa_sig; |
99 | |
b04a7659 |
100 | /*----- DSA stepper -------------------------------------------------------*/ |
101 | |
102 | typedef struct dsa_stepctx { |
103 | |
104 | /* --- To be initialized by the client --- */ |
105 | |
106 | grand *r; /* Random number generator */ |
107 | mp *q; /* Force @p@ to be a multiple */ |
108 | size_t bits; /* Number of bits in the result */ |
109 | unsigned or; /* OR mask for low order bits */ |
110 | } dsa_stepctx; |
111 | |
112 | /* --- @dsa_step@ --- * |
113 | * |
114 | * The stepper chooses random integers, ensures that they are a multiple of |
115 | * @q@ (if specified), sets the low-order bits, and then tests for |
116 | * divisibility by small primes. |
117 | */ |
118 | |
119 | extern int dsa_step(int /*rq*/, pgen_event */*ev*/, void */*p*/); |
120 | |
8b810a45 |
121 | /*----- Functions provided ------------------------------------------------*/ |
122 | |
123 | /* --- @dsa_seed@ --- * |
124 | * |
125 | * Arguments: @dsa_param *dp@ = where to store parameters |
b04a7659 |
126 | * @unsigned ql@ = length of @q@ in bits |
127 | * @unsigned pl@ = length of @p@ in bits |
128 | * @unsigned steps@ = number of steps to find @q@ |
8b810a45 |
129 | * @const void *k@ = pointer to key material |
130 | * @size_t sz@ = size of key material |
b04a7659 |
131 | * @pgen_proc *event@ = event handler function |
132 | * @void *ectx@ = argument for event handler |
8b810a45 |
133 | * |
b04a7659 |
134 | * Returns: @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise. |
8b810a45 |
135 | * |
136 | * Use: Generates the DSA shared parameters from a given seed value. |
b04a7659 |
137 | * This can take quite a long time. |
138 | * |
139 | * The algorithm used is a compatible extension of the method |
140 | * described in the DSA standard, FIPS 186. The standard |
141 | * requires that %$q$% be 160 bits in size (i.e., @ql == 160@) |
142 | * and that the length of %$p$% be %$L = 512 + 64l$% for some |
143 | * %$l$%. Neither limitation applies to this implementation. |
8b810a45 |
144 | */ |
145 | |
b04a7659 |
146 | extern int dsa_seed(dsa_param */*dp*/, unsigned /*ql*/, unsigned /*pl*/, |
147 | unsigned /*steps*/, const void */*k*/, size_t /*sz*/, |
148 | pgen_proc */*event*/, void */*ectx*/); |
8b810a45 |
149 | |
150 | /* --- @dsa_mksig@ --- * |
151 | * |
152 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
b3f05084 |
153 | * @mp *a@ = secret signing key |
154 | * @mp *m@ = message to be signed |
155 | * @mp *k@ = random data |
8b810a45 |
156 | * @mp **rr, **ss@ = where to put output parameters |
157 | * |
158 | * Returns: --- |
159 | * |
160 | * Use: Computes a DSA signature of a message. |
161 | */ |
162 | |
b3f05084 |
163 | extern void dsa_mksig(const dsa_param */*dp*/, mp */*a*/, |
164 | mp */*m*/, mp */*k*/, |
8b810a45 |
165 | mp **/*rr*/, mp **/*ss*/); |
166 | |
167 | /* --- @dsa_sign@ --- * |
168 | * |
169 | * Arguments: @dsa_param *dp@ = pointer to DSA parameters |
170 | * @mp *a@ = pointer to secret signing key |
171 | * @const void *m@ = pointer to message |
172 | * @size_t msz@ = size of the message |
173 | * @const void *k@ = secret random data for securing signature |
174 | * @size_t ksz@ = size of secret data |
175 | * @void *r@ = pointer to output space for @r@ |
176 | * @size_t rsz@ = size of output space for @r@ |
177 | * @void *s@ = pointer to output space for @s@ |
178 | * @size_t ssz@ = size of output space for @s@ |
179 | * |
180 | * Returns: --- |
181 | * |
182 | * Use: Signs a message, storing the results in a big-endian binary |
183 | * form. |
184 | */ |
185 | |
186 | extern void dsa_sign(dsa_param */*dp*/, mp */*a*/, |
187 | const void */*m*/, size_t /*msz*/, |
188 | const void */*k*/, size_t /*ksz*/, |
189 | void */*r*/, size_t /*rsz*/, |
190 | void */*s*/, size_t /*ssz*/); |
191 | |
192 | /* --- @dsa_vrfy@ --- * |
193 | * |
194 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
b3f05084 |
195 | * @mp *y@ = public verification key |
196 | * @mp *m@ = message which was signed |
197 | * @mp *r, *s@ = the signature |
8b810a45 |
198 | * |
199 | * Returns: Zero if the signature is a forgery, nonzero if it's valid. |
200 | * |
201 | * Use: Verifies a DSA digital signature. |
202 | */ |
203 | |
b3f05084 |
204 | extern int dsa_vrfy(const dsa_param */*dp*/, mp */*y*/, |
205 | mp */*m*/, mp */*r*/, mp */*s*/); |
8b810a45 |
206 | |
207 | /* --- @dsa_verify@ --- * |
208 | * |
209 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
b3f05084 |
210 | * @mp *y@ = public verification key |
8b810a45 |
211 | * @const void *m@ = pointer to message block |
212 | * @size_t msz@ = size of message block |
213 | * @const void *r@ = pointer to @r@ signature half |
214 | * @size_t rsz@ = size of @r@ |
215 | * @const void *s@ = pointer to @s@ signature half |
216 | * @size_t ssz@ = size of @s@ |
217 | * |
218 | * Returns: Zero if the signature is a forgery, nonzero if it's valid. |
219 | * |
220 | * Use: Verifies a DSA digital signature. |
221 | */ |
222 | |
b3f05084 |
223 | extern int dsa_verify(const dsa_param */*dp*/, mp */*y*/, |
8b810a45 |
224 | const void */*m*/, size_t /*msz*/, |
225 | const void */*r*/, size_t /*rsz*/, |
226 | const void */*s*/, size_t /*ssz*/); |
227 | |
228 | /*----- That's all, folks -------------------------------------------------*/ |
229 | |
230 | #ifdef __cplusplus |
231 | } |
232 | #endif |
233 | |
234 | #endif |