git.distorted.org.uk Git - u/mdw/catacomb/blob - pkcs1.c

   1 /* -*-c-*-
   2  *
   3  * $Id: pkcs1.c,v 1.1 2000/07/01 11:17:38 mdw Exp $
   4  *
   5  * PKCS#1 1.5 packing
   6  *
   7  * (c) 2000 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: pkcs1.c,v $
  33  * Revision 1.1  2000/07/01 11:17:38  mdw
  34  * New support for PKCS#1 message encoding.
  35  *
  36  */
  37
  38 /*----- Header files ------------------------------------------------------*/
  39
  40 #include <string.h>
  41
  42 #include <mLib/bits.h>
  43 #include <mLib/dstr.h>
  44
  45 #include "grand.h"
  46 #include "pkcs1.h"
  47
  48 /*----- Main code ---------------------------------------------------------*/
  49
  50 /* --- @pkcs1_cryptencode@ --- *
  51  *
  52  * Arguments:   @const void *msg@ = pointer to message data
  53  *              @size_t msz@ = size of message data
  54  *              @void *buf@ = pointer to output buffer
  55  *              @size_t sz@ = size of the output buffer
  56  *              @void *p@ = pointer to PKCS1 parameter block
  57  *
  58  * Returns:     Zero if all went well, negative on failure.
  59  *
  60  * Use:         Implements the operation @EME-PKCS1-V1_5-ENCODE@, as defined
  61  *              in PKCS#1 v. 2.0 (RFC2437).
  62  */
  63
  64 int pkcs1_cryptencode(const void *msg, size_t msz, void *buf, size_t sz,
  65                       void *p)
  66 {
  67   pkcs1 *pp = p;
  68   grand *r = pp->r;
  69   octet *q, *qq;
  70   size_t i, n;
  71
  72   /* --- Ensure that the buffer is sensibly sized --- */
  73
  74   if (pp->epsz + msz + 11 > sz)
  75     return (-1);
  76
  77   /* --- Fill in the buffer --- */
  78
  79   q = buf;
  80   qq = q + sz;
  81   *q++ = 0;
  82   *q++ = 2;
  83   n = sz - msz - pp->epsz - 3;
  84   r->ops->fill(r, q, n);
  85   for (i = 0; i < n; i++) {
  86     if (*q == 0)
  87       *q = r->ops->range(r, 255) + 1;
  88     q++;
  89   }
  90   *q++ = 0;
  91   memcpy(q, pp->ep, pp->epsz);
  92   q += pp->epsz;
  93   memcpy(q, msg, msz);
  94   return (0);
  95 }
  96
  97 /* --- @pkcs1_cryptdecode@ --- *
  98  *
  99  * Arguments:   @const void *buf@ = pointer to encoded buffer
 100  *              @size_t sz@ = size of the encoded buffer
 101  *              @dstr *d@ = pointer to destination string
 102  *              @void *p@ = pointer to PKCS1 parameter block
 103  *
 104  * Returns:     The length of the output string if successful, negative on
 105  *              failure.
 106  *
 107  * Use:         Implements the operation @EME-PKCS1-V1_5-DECODE@, as defined
 108  *              in PKCS#1 v. 2.0 (RFC2437).
 109  */
 110
 111 int pkcs1_cryptdecode(const void *buf, size_t sz, dstr *d, void *p)
 112 {
 113   pkcs1 *pp = p;
 114   const octet *q, *qq;
 115   size_t n, i;
 116
 117   /* --- Check the size of the block looks sane --- */
 118
 119   if (pp->epsz + 11 > sz)
 120     return (-1);
 121   q = buf;
 122   qq = buf + sz;
 123
 124   /* --- Ensure that the block looks OK --- */
 125
 126   if (*q++ != 0 || *q++ != 2)
 127     return (-1);
 128
 129   /* --- Check the nonzero padding --- */
 130
 131   i = 0;
 132   while (*q != 0 && q < qq)
 133     i++, q++;
 134   if (i < 8 || q == qq)
 135     return (-1);
 136   q++;
 137
 138   /* --- Check the encoding parameters --- */
 139
 140   if (memcmp(q, pp->ep, pp->epsz) != 0)
 141     return (-1);
 142   q += pp->epsz;
 143
 144   /* --- Done --- */
 145
 146   n = qq - q;
 147   dstr_putm(d, q, n);
 148   return (n);
 149 }
 150
 151 /* --- @pkcs1_sigencode@ --- *
 152  *
 153  * Arguments:   @const void *msg@ = pointer to message data
 154  *              @size_t msz@ = size of message data
 155  *              @void *buf@ = pointer to output buffer
 156  *              @size_t sz@ = size of the output buffer
 157  *              @void *p@ = pointer to PKCS1 parameter block
 158  *
 159  * Returns:     Zero if all went well, negative on failure.
 160  *
 161  * Use:         Implements the operation @EMSA-PKCS1-V1_5-ENCODE@, as defined
 162  *              in PKCS#1 v. 2.0 (RFC2437).
 163  */
 164
 165 int pkcs1_sigencode(const void *msg, size_t msz, void *buf, size_t sz,
 166                       void *p)
 167 {
 168   pkcs1 *pp = p;
 169   octet *q, *qq;
 170   size_t n;
 171
 172   /* --- Ensure that the buffer is sensibly sized --- */
 173
 174   if (pp->epsz + msz + 11 > sz)
 175     return (-1);
 176
 177   /* --- Fill in the buffer --- */
 178
 179   q = buf;
 180   qq = q + sz;
 181   *q++ = 0;
 182   *q++ = 1;
 183   n = sz - msz - pp->epsz - 3;
 184   memset(q, 0xff, n);
 185   q += n;
 186   *q++ = 0;
 187   memcpy(q, pp->ep, pp->epsz);
 188   q += pp->epsz;
 189   memcpy(q, msg, msz);
 190   return (0);
 191 }
 192
 193 /* --- @pkcs1_sigdecode@ --- *
 194  *
 195  * Arguments:   @const void *buf@ = pointer to encoded buffer
 196  *              @size_t sz@ = size of the encoded buffer
 197  *              @dstr *d@ = pointer to destination string
 198  *              @void *p@ = pointer to PKCS1 parameter block
 199  *
 200  * Returns:     The length of the output string if successful, negative on
 201  *              failure.
 202  *
 203  * Use:         Implements the operation @EMSA-PKCS1-V1_5-DECODE@, as defined
 204  *              in PKCS#1 v. 2.0 (RFC2437).
 205  */
 206
 207 int pkcs1_sigdecode(const void *buf, size_t sz, dstr *d, void *p)
 208 {
 209   pkcs1 *pp = p;
 210   const octet *q, *qq;
 211   size_t i, n;
 212
 213   /* --- Check the size of the block looks sane --- */
 214
 215   if (pp->epsz + 10 > sz)
 216     return (-1);
 217   q = buf;
 218   qq = buf + sz;
 219
 220   /* --- Ensure that the block looks OK --- */
 221
 222   if (*q++ != 0 || *q++ != 1)
 223     return (-1);
 224
 225   /* --- Check the padding --- */
 226
 227   i = 0;
 228   while (*q == 0xff && q < qq)
 229     i++, q++;
 230   if (i < 8 || q == qq)
 231     return (-1);
 232   if (*q != 0)
 233     return (-1);
 234   q++;
 235
 236   /* --- Check the encoding parameters --- */
 237
 238   if (memcmp(q, pp->ep, pp->epsz) != 0)
 239     return (-1);
 240   q += pp->epsz;
 241
 242   /* --- Done --- */
 243
 244   n = qq - q;
 245   dstr_putm(d, q, n);
 246   return (n);
 247 }
 248
 249 /*----- That's all, folks -------------------------------------------------*/