| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: dsa.h,v 1.5 2000/06/17 10:53:42 mdw Exp $ |
| 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 $ |
| 33 | * Revision 1.5 2000/06/17 10:53:42 mdw |
| 34 | * Minor changes for key fetching. Typesetting fixes. |
| 35 | * |
| 36 | * Revision 1.4 1999/12/22 15:52:44 mdw |
| 37 | * Reworking for new prime-search system. |
| 38 | * |
| 39 | * Revision 1.3 1999/12/10 23:29:48 mdw |
| 40 | * Change header file guard names. |
| 41 | * |
| 42 | * Revision 1.2 1999/11/20 22:23:48 mdw |
| 43 | * Allow event handler to abort the search process. |
| 44 | * |
| 45 | * Revision 1.1 1999/11/19 19:28:00 mdw |
| 46 | * Implementation of the Digital Signature Algorithm. |
| 47 | * |
| 48 | */ |
| 49 | |
| 50 | #ifndef CATACOMB_DSA_H |
| 51 | #define CATACOMB_DSA_H |
| 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 | |
| 68 | #ifndef CATACOMB_KEY_H |
| 69 | # include "key.h" |
| 70 | #endif |
| 71 | |
| 72 | #ifndef CATACOMB_MP_H |
| 73 | # include "mp.h" |
| 74 | #endif |
| 75 | |
| 76 | #ifndef CATACOMB_PGEN_H |
| 77 | # include "pgen.h" |
| 78 | #endif |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 150 | /*----- Functions provided ------------------------------------------------*/ |
| 151 | |
| 152 | /* --- @dsa_seed@ --- * |
| 153 | * |
| 154 | * Arguments: @dsa_param *dp@ = where to store parameters |
| 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@ |
| 158 | * @const void *k@ = pointer to key material |
| 159 | * @size_t sz@ = size of key material |
| 160 | * @pgen_proc *event@ = event handler function |
| 161 | * @void *ectx@ = argument for event handler |
| 162 | * |
| 163 | * Returns: @PGEN_DONE@ if everything worked ok; @PGEN_ABORT@ otherwise. |
| 164 | * |
| 165 | * Use: Generates the DSA shared parameters from a given seed value. |
| 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. |
| 173 | */ |
| 174 | |
| 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*/); |
| 178 | |
| 179 | /* --- @dsa_mksig@ --- * |
| 180 | * |
| 181 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
| 182 | * @mp *a@ = secret signing key |
| 183 | * @mp *m@ = message to be signed |
| 184 | * @mp *k@ = random data |
| 185 | * @mp **rr, **ss@ = where to put output parameters |
| 186 | * |
| 187 | * Returns: --- |
| 188 | * |
| 189 | * Use: Computes a DSA signature of a message. |
| 190 | */ |
| 191 | |
| 192 | extern void dsa_mksig(const dsa_param */*dp*/, mp */*a*/, |
| 193 | mp */*m*/, mp */*k*/, |
| 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 |
| 224 | * @mp *y@ = public verification key |
| 225 | * @mp *m@ = message which was signed |
| 226 | * @mp *r, *s@ = the signature |
| 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 | |
| 233 | extern int dsa_vrfy(const dsa_param */*dp*/, mp */*y*/, |
| 234 | mp */*m*/, mp */*r*/, mp */*s*/); |
| 235 | |
| 236 | /* --- @dsa_verify@ --- * |
| 237 | * |
| 238 | * Arguments: @const dsa_param *dp@ = pointer to DSA parameters |
| 239 | * @mp *y@ = public verification key |
| 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 | |
| 252 | extern int dsa_verify(const dsa_param */*dp*/, mp */*y*/, |
| 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 |