| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: pkcs1.c,v 1.3 2000/10/08 12:07:04 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 1.3 2000/10/08 12:07:04 mdw |
| 34 | * Don't do arithmetic on @void *@ pointers. |
| 35 | * |
| 36 | * Revision 1.2 2000/07/05 17:49:48 mdw |
| 37 | * Fix decoding functions, so that they don't run off the end of the |
| 38 | * buffer. |
| 39 | * |
| 40 | * Revision 1.1 2000/07/01 11:17:38 mdw |
| 41 | * New support for PKCS#1 message encoding. |
| 42 | * |
| 43 | */ |
| 44 | |
| 45 | /*----- Header files ------------------------------------------------------*/ |
| 46 | |
| 47 | #include <string.h> |
| 48 | |
| 49 | #include <mLib/bits.h> |
| 50 | #include <mLib/dstr.h> |
| 51 | |
| 52 | #include "grand.h" |
| 53 | #include "pkcs1.h" |
| 54 | |
| 55 | /*----- Main code ---------------------------------------------------------*/ |
| 56 | |
| 57 | /* --- @pkcs1_cryptencode@ --- * |
| 58 | * |
| 59 | * Arguments: @const void *msg@ = pointer to message data |
| 60 | * @size_t msz@ = size of message data |
| 61 | * @void *buf@ = pointer to output buffer |
| 62 | * @size_t sz@ = size of the output buffer |
| 63 | * @void *p@ = pointer to PKCS1 parameter block |
| 64 | * |
| 65 | * Returns: Zero if all went well, negative on failure. |
| 66 | * |
| 67 | * Use: Implements the operation @EME-PKCS1-V1_5-ENCODE@, as defined |
| 68 | * in PKCS#1 v. 2.0 (RFC2437). |
| 69 | */ |
| 70 | |
| 71 | int pkcs1_cryptencode(const void *msg, size_t msz, void *buf, size_t sz, |
| 72 | void *p) |
| 73 | { |
| 74 | pkcs1 *pp = p; |
| 75 | grand *r = pp->r; |
| 76 | octet *q, *qq; |
| 77 | size_t i, n; |
| 78 | |
| 79 | /* --- Ensure that the buffer is sensibly sized --- */ |
| 80 | |
| 81 | if (pp->epsz + msz + 11 > sz) |
| 82 | return (-1); |
| 83 | |
| 84 | /* --- Fill in the buffer --- */ |
| 85 | |
| 86 | q = buf; |
| 87 | qq = q + sz; |
| 88 | *q++ = 0; |
| 89 | *q++ = 2; |
| 90 | n = sz - msz - pp->epsz - 3; |
| 91 | r->ops->fill(r, q, n); |
| 92 | for (i = 0; i < n; i++) { |
| 93 | if (*q == 0) |
| 94 | *q = r->ops->range(r, 255) + 1; |
| 95 | q++; |
| 96 | } |
| 97 | *q++ = 0; |
| 98 | memcpy(q, pp->ep, pp->epsz); |
| 99 | q += pp->epsz; |
| 100 | memcpy(q, msg, msz); |
| 101 | return (0); |
| 102 | } |
| 103 | |
| 104 | /* --- @pkcs1_cryptdecode@ --- * |
| 105 | * |
| 106 | * Arguments: @const void *buf@ = pointer to encoded buffer |
| 107 | * @size_t sz@ = size of the encoded buffer |
| 108 | * @dstr *d@ = pointer to destination string |
| 109 | * @void *p@ = pointer to PKCS1 parameter block |
| 110 | * |
| 111 | * Returns: The length of the output string if successful, negative on |
| 112 | * failure. |
| 113 | * |
| 114 | * Use: Implements the operation @EME-PKCS1-V1_5-DECODE@, as defined |
| 115 | * in PKCS#1 v. 2.0 (RFC2437). |
| 116 | */ |
| 117 | |
| 118 | int pkcs1_cryptdecode(const void *buf, size_t sz, dstr *d, void *p) |
| 119 | { |
| 120 | pkcs1 *pp = p; |
| 121 | const octet *q, *qq; |
| 122 | size_t n, i; |
| 123 | |
| 124 | /* --- Check the size of the block looks sane --- */ |
| 125 | |
| 126 | if (pp->epsz + 11 > sz) |
| 127 | return (-1); |
| 128 | q = buf; |
| 129 | qq = q + sz; |
| 130 | |
| 131 | /* --- Ensure that the block looks OK --- */ |
| 132 | |
| 133 | if (*q++ != 0 || *q++ != 2) |
| 134 | return (-1); |
| 135 | |
| 136 | /* --- Check the nonzero padding --- */ |
| 137 | |
| 138 | i = 0; |
| 139 | while (*q != 0 && q < qq) |
| 140 | i++, q++; |
| 141 | if (i < 8 || qq - q < pp->epsz + 1) |
| 142 | return (-1); |
| 143 | q++; |
| 144 | |
| 145 | /* --- Check the encoding parameters --- */ |
| 146 | |
| 147 | if (memcmp(q, pp->ep, pp->epsz) != 0) |
| 148 | return (-1); |
| 149 | q += pp->epsz; |
| 150 | |
| 151 | /* --- Done --- */ |
| 152 | |
| 153 | n = qq - q; |
| 154 | dstr_putm(d, q, n); |
| 155 | return (n); |
| 156 | } |
| 157 | |
| 158 | /* --- @pkcs1_sigencode@ --- * |
| 159 | * |
| 160 | * Arguments: @const void *msg@ = pointer to message data |
| 161 | * @size_t msz@ = size of message data |
| 162 | * @void *buf@ = pointer to output buffer |
| 163 | * @size_t sz@ = size of the output buffer |
| 164 | * @void *p@ = pointer to PKCS1 parameter block |
| 165 | * |
| 166 | * Returns: Zero if all went well, negative on failure. |
| 167 | * |
| 168 | * Use: Implements the operation @EMSA-PKCS1-V1_5-ENCODE@, as defined |
| 169 | * in PKCS#1 v. 2.0 (RFC2437). |
| 170 | */ |
| 171 | |
| 172 | int pkcs1_sigencode(const void *msg, size_t msz, void *buf, size_t sz, |
| 173 | void *p) |
| 174 | { |
| 175 | pkcs1 *pp = p; |
| 176 | octet *q, *qq; |
| 177 | size_t n; |
| 178 | |
| 179 | /* --- Ensure that the buffer is sensibly sized --- */ |
| 180 | |
| 181 | if (pp->epsz + msz + 11 > sz) |
| 182 | return (-1); |
| 183 | |
| 184 | /* --- Fill in the buffer --- */ |
| 185 | |
| 186 | q = buf; |
| 187 | qq = q + sz; |
| 188 | *q++ = 0; |
| 189 | *q++ = 1; |
| 190 | n = sz - msz - pp->epsz - 3; |
| 191 | memset(q, 0xff, n); |
| 192 | q += n; |
| 193 | *q++ = 0; |
| 194 | memcpy(q, pp->ep, pp->epsz); |
| 195 | q += pp->epsz; |
| 196 | memcpy(q, msg, msz); |
| 197 | return (0); |
| 198 | } |
| 199 | |
| 200 | /* --- @pkcs1_sigdecode@ --- * |
| 201 | * |
| 202 | * Arguments: @const void *buf@ = pointer to encoded buffer |
| 203 | * @size_t sz@ = size of the encoded buffer |
| 204 | * @dstr *d@ = pointer to destination string |
| 205 | * @void *p@ = pointer to PKCS1 parameter block |
| 206 | * |
| 207 | * Returns: The length of the output string if successful, negative on |
| 208 | * failure. |
| 209 | * |
| 210 | * Use: Implements the operation @EMSA-PKCS1-V1_5-DECODE@, as defined |
| 211 | * in PKCS#1 v. 2.0 (RFC2437). |
| 212 | */ |
| 213 | |
| 214 | int pkcs1_sigdecode(const void *buf, size_t sz, dstr *d, void *p) |
| 215 | { |
| 216 | pkcs1 *pp = p; |
| 217 | const octet *q, *qq; |
| 218 | size_t i, n; |
| 219 | |
| 220 | /* --- Check the size of the block looks sane --- */ |
| 221 | |
| 222 | if (pp->epsz + 10 > sz) |
| 223 | return (-1); |
| 224 | q = buf; |
| 225 | qq = q + sz; |
| 226 | |
| 227 | /* --- Ensure that the block looks OK --- */ |
| 228 | |
| 229 | if (*q++ != 0 || *q++ != 1) |
| 230 | return (-1); |
| 231 | |
| 232 | /* --- Check the padding --- */ |
| 233 | |
| 234 | i = 0; |
| 235 | while (*q == 0xff && q < qq) |
| 236 | i++, q++; |
| 237 | if (i < 8 || qq - q < pp->epsz + 1 || *q++ != 0) |
| 238 | return (-1); |
| 239 | |
| 240 | /* --- Check the encoding parameters --- */ |
| 241 | |
| 242 | if (memcmp(q, pp->ep, pp->epsz) != 0) |
| 243 | return (-1); |
| 244 | q += pp->epsz; |
| 245 | |
| 246 | /* --- Done --- */ |
| 247 | |
| 248 | n = qq - q; |
| 249 | dstr_putm(d, q, n); |
| 250 | return (n); |
| 251 | } |
| 252 | |
| 253 | /*----- That's all, folks -------------------------------------------------*/ |