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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: dsa.h,v 1.9 2004/04/08 01:36:15 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 | |
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30 | #ifndef CATACOMB_DSA_H |
31 | #define CATACOMB_DSA_H |
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32 | |
33 | #ifdef __cplusplus |
34 | extern "C" { |
35 | #endif |
36 | |
37 | /*----- Notes on the Digital Signature Algorithm --------------------------* |
38 | * |
39 | * The Digital Signature Algorithm was designed by the NSA for US Government |
40 | * use. It's defined in FIPS 186-1. Whether it's covered by patents is |
41 | * under dispute, although it looks relatively clear. It produces compact |
42 | * signatures, and is relatively easy to compute. It seems strong, if |
43 | * appropriate parameters are chosen. |
44 | */ |
45 | |
46 | /*----- Header files ------------------------------------------------------*/ |
47 | |
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48 | #ifndef CATACOMB_DH_H |
49 | # include "dh.h" |
50 | #endif |
51 | |
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52 | #ifndef CATACOMB_KEY_H |
53 | # include "key.h" |
54 | #endif |
55 | |
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56 | #ifndef CATACOMB_KEYCHECK_H |
57 | # include "keycheck.h" |
58 | #endif |
59 | |
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60 | #ifndef CATACOMB_MP_H |
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61 | # include "mp.h" |
62 | #endif |
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63 | |
64 | #ifndef CATACOMB_PGEN_H |
65 | # include "pgen.h" |
66 | #endif |
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67 | |
68 | /*----- Data structures ---------------------------------------------------*/ |
69 | |
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70 | /* --- The parameters and keys are the same as for Diffie-Hellman --- */ |
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71 | |
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72 | typedef dh_param dsa_param; |
73 | typedef dh_pub dsa_pub; |
74 | typedef dh_priv dsa_priv; |
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75 | |
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76 | /* --- DSA key seed structure --- */ |
77 | |
78 | typedef struct dsa_seed { |
79 | void *p; /* Pointer to seed material */ |
80 | size_t sz; /* Size of seed material */ |
81 | unsigned count; /* Iterations to find @p@ */ |
82 | } dsa_seed; |
83 | |
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84 | /* --- DSA signature structure --- * |
85 | * |
86 | * This is the recommended structure for a DSA signature. The actual signing |
87 | * function can cope with arbitrary-sized objects given appropriate |
88 | * parameters, however. |
89 | */ |
90 | |
91 | #define DSA_SIGLEN 20 |
92 | |
93 | typedef struct dsa_sig { |
94 | octet r[DSA_SIGLEN]; /* 160-bit @r@ value */ |
95 | octet s[DSA_SIGLEN]; /* 160-bit @s@ value */ |
96 | } dsa_sig; |
97 | |
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98 | /*----- Key fetching ------------------------------------------------------*/ |
99 | |
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100 | #define dsa_paramfetch dh_paramfetch |
101 | #define dsa_pubfetch dh_pubfetch |
102 | #define dsa_privfetch dh_privfetch |
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103 | |
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104 | #define DSA_PARAMFETCHSZ DH_PARAMFETCHSZ |
105 | #define DSA_PUBFETCHSZ DH_PUBFETCHSZ |
106 | #define DSA_PRIVFETCHSZ DH_PRIVFETCHSZ |
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107 | |
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108 | #define dsa_paramfree dh_paramfree |
109 | #define dsa_pubfree dh_pubfree |
110 | #define dsa_privfree dh_privfree |
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111 | |
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112 | /*----- DSA stepper -------------------------------------------------------*/ |
113 | |
114 | typedef struct dsa_stepctx { |
115 | |
116 | /* --- To be initialized by the client --- */ |
117 | |
118 | grand *r; /* Random number generator */ |
119 | mp *q; /* Force @p@ to be a multiple */ |
120 | size_t bits; /* Number of bits in the result */ |
121 | unsigned or; /* OR mask for low order bits */ |
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122 | unsigned count; /* Counts the number of steps made */ |
123 | void *seedbuf; /* Pointer to seed buffer */ |
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124 | } dsa_stepctx; |
125 | |
126 | /* --- @dsa_step@ --- * |
127 | * |
128 | * The stepper chooses random integers, ensures that they are a multiple of |
129 | * @q@ (if specified), sets the low-order bits, and then tests for |
130 | * divisibility by small primes. |
131 | */ |
132 | |
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133 | extern pgen_proc dsa_step; |
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134 | |
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135 | /*----- Functions provided ------------------------------------------------*/ |
136 | |
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137 | /* --- @dsa_gen@ --- * |
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138 | * |
139 | * Arguments: @dsa_param *dp@ = where to store parameters |
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140 | * @unsigned ql@ = length of @q@ in bits |
141 | * @unsigned pl@ = length of @p@ in bits |
142 | * @unsigned steps@ = number of steps to find @q@ |
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143 | * @const void *k@ = pointer to key material |
144 | * @size_t sz@ = size of key material |
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145 | * @dsa_seed *sd@ = optional pointer for output seed information |
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146 | * @pgen_proc *event@ = event handler function |
147 | * @void *ectx@ = argument for event handler |
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148 | * |
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149 | * Returns: @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise. |
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150 | * |
151 | * Use: Generates the DSA shared parameters from a given seed value. |
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152 | * This can take quite a long time. |
153 | * |
154 | * The algorithm used is a compatible extension of the method |
155 | * described in the DSA standard, FIPS 186. The standard |
156 | * requires that %$q$% be 160 bits in size (i.e., @ql == 160@) |
157 | * and that the length of %$p$% be %$L = 512 + 64l$% for some |
158 | * %$l$%. Neither limitation applies to this implementation. |
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159 | */ |
160 | |
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161 | extern int dsa_gen(dsa_param */*dp*/, unsigned /*ql*/, unsigned /*pl*/, |
162 | unsigned /*steps*/, const void */*k*/, size_t /*sz*/, |
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163 | dsa_seed */*sd*/, pgen_proc */*event*/, void */*ectx*/); |
164 | |
165 | /* --- @dsa_checkparam@ --- * |
166 | * |
167 | * Arguments: @keycheck *kc@ = keycheck state |
168 | * @const dsa_param *dp@ = pointer to the parameter set |
169 | * @const dsa_seed *ds@ = pointer to seed information |
170 | * |
171 | * Returns: Zero if all OK, or return status from function. |
172 | * |
173 | * Use: Checks a set of DSA parameters for consistency and security. |
174 | */ |
175 | |
176 | extern int dsa_checkparam(keycheck */*kc*/, const dsa_param */*dp*/, |
177 | const dsa_seed */*ds*/); |
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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*/); |
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256 | |
257 | /*----- That's all, folks -------------------------------------------------*/ |
258 | |
259 | #ifdef __cplusplus |
260 | } |
261 | #endif |
262 | |
263 | #endif |