| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: dsa.h,v 1.2 1999/11/20 22:23:48 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 1.2 1999/11/20 22:23:48 mdw |
| 34 | * Allow event handler to abort the search process. |
| 35 | * |
| 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 |
| 116 | * @int (*proc)(int ev, mp *m, void *p)@ = event procedure |
| 117 | * @size_t sz@ = size of key material |
| 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 |
| 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. |
| 134 | */ |
| 135 | |
| 136 | extern int dsa_seed(dsa_param */*dp*/, unsigned /*l*/, |
| 137 | const void */*k*/, size_t /*sz*/, |
| 138 | int (*proc)(int /*ev*/, mp */*m*/, void */*p*/), |
| 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 |