git.distorted.org.uk Git - u/mdw/catacomb/blob - key-binary.c

   1 /* -*-c-*-
   2  *
   3  * $Id: key-binary.c,v 1.4 2004/03/28 01:58:47 mdw Exp $
   4  *
   5  * Key binary encoding
   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: key-binary.c,v $
  33  * Revision 1.4  2004/03/28 01:58:47  mdw
  34  * Generate, store and retreive elliptic curve keys.
  35  *
  36  * Revision 1.3  2001/02/03 11:57:00  mdw
  37  * Track mLib change: symbols no longer need to include a terminating
  38  * null.
  39  *
  40  * Revision 1.2  2000/06/17 11:25:20  mdw
  41  * Use secure memory interface from MP library.
  42  *
  43  * Revision 1.1  2000/02/12 18:21:02  mdw
  44  * Overhaul of key management (again).
  45  *
  46  */
  47
  48 /*----- Header files ------------------------------------------------------*/
  49
  50 #include <stdlib.h>
  51 #include <string.h>
  52
  53 #include <mLib/bits.h>
  54 #include <mLib/dstr.h>
  55 #include <mLib/sub.h>
  56 #include <mLib/sym.h>
  57
  58 #include "key-data.h"
  59 #include "mp.h"
  60 #include "mptext.h"
  61
  62 /*----- Main code ---------------------------------------------------------*/
  63
  64 /* --- @key_decode@ --- *
  65  *
  66  * Arguments:   @const void *p@ = pointer to buffer to read
  67  *              @size_t sz@ = size of the buffer
  68  *              @key_data *k@ = pointer to key data block to write to
  69  *
  70  * Returns:     Zero if everything worked, nonzero otherwise.
  71  *
  72  * Use:         Decodes a binary representation of a key.
  73  */
  74
  75 int key_decode(const void *p, size_t sz, key_data *k)
  76 {
  77   const octet *q = p;
  78   size_t psz;
  79   unsigned e;
  80
  81   /* --- Parse the header information --- *
  82    *
  83    * Make sure the size matches external reality.  Security holes have been
  84    * known to creep in without this sort of check.  (No, this isn't an after-
  85    * the-fact patch-up.)
  86    */
  87
  88   e = LOAD16(q);
  89   psz = LOAD16(q + 2);
  90   if (psz + 4 > sz)
  91     return (-1);
  92   k->e = e;
  93
  94   /* --- Now decide what to do --- */
  95
  96   switch (e & KF_ENCMASK) {
  97
  98     /* --- Plain binary data --- */
  99
 100     case KENC_BINARY:
 101     case KENC_ENCRYPT:
 102       k->u.k.k = sub_alloc(psz);
 103       memcpy(k->u.k.k, q + 4, psz);
 104       k->u.k.sz = psz;
 105       break;
 106
 107     /* --- Multiprecision integer data --- */
 108
 109     case KENC_MP:
 110       k->u.m = mp_loadb(k->e & KF_BURN ? MP_NEWSEC : MP_NEW, q + 4, psz);
 111       break;
 112
 113     /* --- String data --- */
 114
 115     case KENC_STRING:
 116       k->u.p = xmalloc(sz + 1);
 117       memcpy(k->u.p, q + 4, sz);
 118       k->u.p[sz] = 0;
 119       break;
 120
 121     /* --- Elliptic curve point data --- */
 122
 123     case KENC_EC: {
 124       size_t xsz, ysz;
 125       if (sz < 2) return (-1);
 126       xsz = LOAD16(q + 4);
 127       if (sz < xsz + 4) return (-1);
 128       ysz = LOAD16(q + 6 + xsz);
 129       if (sz < xsz + ysz + 4) return (-1);
 130       EC_CREATE(&k->u.e);
 131       k->u.e.x = mp_loadb(MP_NEW, q + 6, xsz);
 132       k->u.e.y = mp_loadb(MP_NEW, q + 6 + xsz, ysz);
 133     } break;
 134
 135     /* --- Structured key data --- */
 136
 137     case KENC_STRUCT: {
 138       dstr d = DSTR_INIT;
 139       key_struct *ks;
 140       unsigned f;
 141
 142       if ((k->e & ~KF_ENCMASK) || (psz & 3))
 143         return (-1);
 144       q += 4;
 145       sym_create(&k->u.s);
 146
 147       while (psz) {
 148
 149         /* --- Read the tag string --- */
 150
 151         DRESET(&d);
 152         sz = LOAD8(q);
 153         if (sz >= psz)
 154           goto fail;
 155         DPUTM(&d, q + 1, sz);
 156         DPUTZ(&d);
 157         sz = (sz + 4) & ~3;
 158         q += sz; psz -= sz;
 159
 160         /* --- Read the encoding and size --- */
 161
 162         e = LOAD16(q);
 163         sz = (LOAD16(q + 2) + 7) & ~3;
 164         if (sz > psz)
 165           goto fail;
 166
 167         /* --- Create a table node and fill it in --- */
 168
 169         ks = sym_find(&k->u.s, d.buf, d.len, sizeof(*ks), &f);
 170         if (f)
 171           goto fail;
 172         if (key_decode(q, sz, &ks->k)) {
 173           sym_remove(&k->u.s, ks);
 174           goto fail;
 175         }
 176         psz -= sz;
 177         q += sz;
 178       }
 179       dstr_destroy(&d);
 180       break;
 181
 182       /* --- Tidy up after a failure --- */
 183
 184     fail:
 185       dstr_destroy(&d);
 186       key_destroy(k);
 187       return (-1);
 188     } break;
 189
 190     /* --- Everything else --- */
 191
 192     default:
 193       return (-1);
 194   }
 195
 196   /* --- OK, that was good --- */
 197
 198   return (0);
 199 }
 200
 201 /* --- @key_encode@ --- *
 202  *
 203  * Arguments:   @key_data *k@ = pointer to key data block
 204  *              @dstr *d@ = pointer to destination string
 205  *              @const key_filter *kf@ = pointer to key selection block
 206  *
 207  * Returns:     Nonzero if an item was actually written.
 208  *
 209  * Use:         Encodes a key block as binary data.
 210  */
 211
 212 int key_encode(key_data *k, dstr *d, const key_filter *kf)
 213 {
 214   int rc = 0;
 215   if (!KEY_MATCH(k, kf))
 216     return (0);
 217   switch (k->e & KF_ENCMASK) {
 218     case KENC_BINARY:
 219     case KENC_ENCRYPT: {
 220       char *p;
 221
 222       DENSURE(d, (k->u.k.sz + 7) & ~3);
 223       p = d->buf + d->len;
 224       STORE16(p, k->e);
 225       STORE16(p + 2, k->u.k.sz);
 226       d->len += 4;
 227       DPUTM(d, k->u.k.k, k->u.k.sz);
 228       rc = 1;
 229     } break;
 230
 231     case KENC_MP: {
 232       char *p;
 233       size_t sz = mp_octets(k->u.m);
 234
 235       DENSURE(d, (sz + 7) & ~3);
 236       p = d->buf + d->len;
 237       STORE16(p, k->e);
 238       STORE16(p + 2, sz);
 239       mp_storeb(k->u.m, p + 4, sz);
 240       d->len += sz + 4;
 241       rc = 1;
 242     } break;
 243
 244     case KENC_STRING: {
 245       char *p;
 246       size_t sz = strlen(k->u.p);
 247
 248       DENSURE(d, (sz + 7) & ~3);
 249       p = d->buf + d->len;
 250       STORE16(p, k->e);
 251       STORE16(p + 2, sz);
 252       memcpy(p + 4, k->u.p, sz);
 253       d->len += sz + 4;
 254       rc = 1;
 255     } break;
 256
 257     case KENC_EC: {
 258       char *p;
 259       size_t xsz = mp_octets(k->u.e.x), ysz = mp_octets(k->u.e.y);
 260       size_t sz = xsz + ysz + 4;
 261
 262       DENSURE(d, (sz + 7) & ~3);
 263       p = d->buf + d->len;
 264       STORE16(p, k->e);
 265       STORE16(p + 2, sz);
 266       STORE16(p + 4, xsz);
 267       mp_storeb(k->u.e.x, p + 6, xsz);
 268       STORE16(p + 6 + xsz, ysz);
 269       mp_storeb(k->u.e.y, p + 8 + xsz, ysz);
 270       d->len += sz + 4;
 271       rc = 1;
 272     } break;
 273
 274     case KENC_STRUCT: {
 275       size_t n;
 276       char *p;
 277       key_struct *ks;
 278       sym_iter i;
 279
 280       n = d->len;
 281       DENSURE(d, 4);
 282       p = d->buf + n;
 283       STORE16(p, k->e & KF_ENCMASK);
 284       d->len += 4;
 285       for (sym_mkiter(&i, &k->u.s); (ks = sym_next(&i)) != 0; ) {
 286         size_t o = d->len;
 287         DENSURE(d, 1);
 288         *(octet *)(d->buf + d->len++) = strlen(SYM_NAME(ks));
 289         DPUTS(d, SYM_NAME(ks));
 290         while (d->len & 3)
 291           DPUTC(d, 0);
 292         if (key_encode(&ks->k, d, kf))
 293           rc = 1;
 294         else
 295           d->len = o;
 296       }
 297       if (!rc)
 298         d->len = n;
 299       else {
 300         p = d->buf + n + 2;
 301         n = d->len - n - 4;
 302         STORE16(p,  n);
 303       }
 304     } break;
 305   }
 306   while (d->len & 3)
 307     DPUTC(d, 0);
 308   return (rc);
 309 }
 310
 311 /*----- That's all, folks -------------------------------------------------*/