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

   1 /* -*-c-*-
   2  *
   3  * $Id: pkcs1.c,v 1.2 2000/07/05 17:49:48 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 1.2  2000/07/05 17:49:48  mdw
  34  * Fix decoding functions, so that they don't run off the end of the
  35  * buffer.
  36  *
  37  * Revision 1.1  2000/07/01 11:17:38  mdw
  38  * New support for PKCS#1 message encoding.
  39  *
  40  */
  41
  42 /*----- Header files ------------------------------------------------------*/
  43
  44 #include <string.h>
  45
  46 #include <mLib/bits.h>
  47 #include <mLib/dstr.h>
  48
  49 #include "grand.h"
  50 #include "pkcs1.h"
  51
  52 /*----- Main code ---------------------------------------------------------*/
  53
  54 /* --- @pkcs1_cryptencode@ --- *
  55  *
  56  * Arguments:   @const void *msg@ = pointer to message data
  57  *              @size_t msz@ = size of message data
  58  *              @void *buf@ = pointer to output buffer
  59  *              @size_t sz@ = size of the output buffer
  60  *              @void *p@ = pointer to PKCS1 parameter block
  61  *
  62  * Returns:     Zero if all went well, negative on failure.
  63  *
  64  * Use:         Implements the operation @EME-PKCS1-V1_5-ENCODE@, as defined
  65  *              in PKCS#1 v. 2.0 (RFC2437).
  66  */
  67
  68 int pkcs1_cryptencode(const void *msg, size_t msz, void *buf, size_t sz,
  69                       void *p)
  70 {
  71   pkcs1 *pp = p;
  72   grand *r = pp->r;
  73   octet *q, *qq;
  74   size_t i, n;
  75
  76   /* --- Ensure that the buffer is sensibly sized --- */
  77
  78   if (pp->epsz + msz + 11 > sz)
  79     return (-1);
  80
  81   /* --- Fill in the buffer --- */
  82
  83   q = buf;
  84   qq = q + sz;
  85   *q++ = 0;
  86   *q++ = 2;
  87   n = sz - msz - pp->epsz - 3;
  88   r->ops->fill(r, q, n);
  89   for (i = 0; i < n; i++) {
  90     if (*q == 0)
  91       *q = r->ops->range(r, 255) + 1;
  92     q++;
  93   }
  94   *q++ = 0;
  95   memcpy(q, pp->ep, pp->epsz);
  96   q += pp->epsz;
  97   memcpy(q, msg, msz);
  98   return (0);
  99 }
 100
 101 /* --- @pkcs1_cryptdecode@ --- *
 102  *
 103  * Arguments:   @const void *buf@ = pointer to encoded buffer
 104  *              @size_t sz@ = size of the encoded buffer
 105  *              @dstr *d@ = pointer to destination string
 106  *              @void *p@ = pointer to PKCS1 parameter block
 107  *
 108  * Returns:     The length of the output string if successful, negative on
 109  *              failure.
 110  *
 111  * Use:         Implements the operation @EME-PKCS1-V1_5-DECODE@, as defined
 112  *              in PKCS#1 v. 2.0 (RFC2437).
 113  */
 114
 115 int pkcs1_cryptdecode(const void *buf, size_t sz, dstr *d, void *p)
 116 {
 117   pkcs1 *pp = p;
 118   const octet *q, *qq;
 119   size_t n, i;
 120
 121   /* --- Check the size of the block looks sane --- */
 122
 123   if (pp->epsz + 11 > sz)
 124     return (-1);
 125   q = buf;
 126   qq = buf + sz;
 127
 128   /* --- Ensure that the block looks OK --- */
 129
 130   if (*q++ != 0 || *q++ != 2)
 131     return (-1);
 132
 133   /* --- Check the nonzero padding --- */
 134
 135   i = 0;
 136   while (*q != 0 && q < qq)
 137     i++, q++;
 138   if (i < 8 || qq - q < pp->epsz + 1)
 139     return (-1);
 140   q++;
 141
 142   /* --- Check the encoding parameters --- */
 143
 144   if (memcmp(q, pp->ep, pp->epsz) != 0)
 145     return (-1);
 146   q += pp->epsz;
 147
 148   /* --- Done --- */
 149
 150   n = qq - q;
 151   dstr_putm(d, q, n);
 152   return (n);
 153 }
 154
 155 /* --- @pkcs1_sigencode@ --- *
 156  *
 157  * Arguments:   @const void *msg@ = pointer to message data
 158  *              @size_t msz@ = size of message data
 159  *              @void *buf@ = pointer to output buffer
 160  *              @size_t sz@ = size of the output buffer
 161  *              @void *p@ = pointer to PKCS1 parameter block
 162  *
 163  * Returns:     Zero if all went well, negative on failure.
 164  *
 165  * Use:         Implements the operation @EMSA-PKCS1-V1_5-ENCODE@, as defined
 166  *              in PKCS#1 v. 2.0 (RFC2437).
 167  */
 168
 169 int pkcs1_sigencode(const void *msg, size_t msz, void *buf, size_t sz,
 170                       void *p)
 171 {
 172   pkcs1 *pp = p;
 173   octet *q, *qq;
 174   size_t n;
 175
 176   /* --- Ensure that the buffer is sensibly sized --- */
 177
 178   if (pp->epsz + msz + 11 > sz)
 179     return (-1);
 180
 181   /* --- Fill in the buffer --- */
 182
 183   q = buf;
 184   qq = q + sz;
 185   *q++ = 0;
 186   *q++ = 1;
 187   n = sz - msz - pp->epsz - 3;
 188   memset(q, 0xff, n);
 189   q += n;
 190   *q++ = 0;
 191   memcpy(q, pp->ep, pp->epsz);
 192   q += pp->epsz;
 193   memcpy(q, msg, msz);
 194   return (0);
 195 }
 196
 197 /* --- @pkcs1_sigdecode@ --- *
 198  *
 199  * Arguments:   @const void *buf@ = pointer to encoded buffer
 200  *              @size_t sz@ = size of the encoded buffer
 201  *              @dstr *d@ = pointer to destination string
 202  *              @void *p@ = pointer to PKCS1 parameter block
 203  *
 204  * Returns:     The length of the output string if successful, negative on
 205  *              failure.
 206  *
 207  * Use:         Implements the operation @EMSA-PKCS1-V1_5-DECODE@, as defined
 208  *              in PKCS#1 v. 2.0 (RFC2437).
 209  */
 210
 211 int pkcs1_sigdecode(const void *buf, size_t sz, dstr *d, void *p)
 212 {
 213   pkcs1 *pp = p;
 214   const octet *q, *qq;
 215   size_t i, n;
 216
 217   /* --- Check the size of the block looks sane --- */
 218
 219   if (pp->epsz + 10 > sz)
 220     return (-1);
 221   q = buf;
 222   qq = buf + sz;
 223
 224   /* --- Ensure that the block looks OK --- */
 225
 226   if (*q++ != 0 || *q++ != 1)
 227     return (-1);
 228
 229   /* --- Check the padding --- */
 230
 231   i = 0;
 232   while (*q == 0xff && q < qq)
 233     i++, q++;
 234   if (i < 8 || qq - q < pp->epsz + 1 || *q++ != 0)
 235     return (-1);
 236
 237   /* --- Check the encoding parameters --- */
 238
 239   if (memcmp(q, pp->ep, pp->epsz) != 0)
 240     return (-1);
 241   q += pp->epsz;
 242
 243   /* --- Done --- */
 244
 245   n = qq - q;
 246   dstr_putm(d, q, n);
 247   return (n);
 248 }
 249
 250 /*----- That's all, folks -------------------------------------------------*/