| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: oaep.c,v 1.4 2002/01/13 13:50:21 mdw Exp $ |
| 4 | * |
| 5 | * Optimal asymmetric encryption 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: oaep.c,v $ |
| 33 | * Revision 1.4 2002/01/13 13:50:21 mdw |
| 34 | * Allow only one error return, to frustrate Manger's attack against OAEP. |
| 35 | * |
| 36 | * Revision 1.3 2001/02/22 09:04:39 mdw |
| 37 | * Fix memory leaks. |
| 38 | * |
| 39 | * Revision 1.2 2000/07/15 10:01:48 mdw |
| 40 | * Test rig added, based on RIPEMD160-MGF1 test vectors. |
| 41 | * |
| 42 | * Revision 1.1 2000/07/01 11:18:30 mdw |
| 43 | * Support for Optimal Asymmetric Encryption Padding. |
| 44 | * |
| 45 | */ |
| 46 | |
| 47 | /*----- Header files ------------------------------------------------------*/ |
| 48 | |
| 49 | #include <string.h> |
| 50 | |
| 51 | #include <mLib/alloc.h> |
| 52 | #include <mLib/bits.h> |
| 53 | #include <mLib/dstr.h> |
| 54 | |
| 55 | #include "gcipher.h" |
| 56 | #include "ghash.h" |
| 57 | #include "grand.h" |
| 58 | #include "oaep.h" |
| 59 | |
| 60 | /*----- Main code ---------------------------------------------------------*/ |
| 61 | |
| 62 | /* --- @oaep_encode@ --- * |
| 63 | * |
| 64 | * Arguments: @const void *msg@ = pointer to message data |
| 65 | * @size_t msz@ = size of message data |
| 66 | * @void *buf@ = pointer to output buffer |
| 67 | * @size_t sz@ = size of the output buffer |
| 68 | * @void *p@ = pointer to OAEP parameter block |
| 69 | * |
| 70 | * Returns: Zero if all went well, negative on failure. |
| 71 | * |
| 72 | * Use: Implements the operation @EME-OAEP-ENCODE@, as defined in |
| 73 | * PKCS#1 v. 2.0 (RFC2437). |
| 74 | */ |
| 75 | |
| 76 | int oaep_encode(const void *msg, size_t msz, void *buf, size_t sz, void *p) |
| 77 | { |
| 78 | oaep *o = p; |
| 79 | size_t hsz = o->ch->hashsz; |
| 80 | ghash *h; |
| 81 | octet *q, *mq, *qq; |
| 82 | octet *pp; |
| 83 | gcipher *c; |
| 84 | size_t n; |
| 85 | |
| 86 | /* --- Ensure that everything is sensibly sized --- */ |
| 87 | |
| 88 | if (2 * hsz + 2 + msz > sz) |
| 89 | return (-1); |
| 90 | |
| 91 | /* --- Make the `seed' value --- */ |
| 92 | |
| 93 | q = buf; |
| 94 | *q++ = 0; sz--; |
| 95 | mq = q + hsz; |
| 96 | qq = q + sz; |
| 97 | o->r->ops->fill(o->r, q, hsz); |
| 98 | |
| 99 | /* --- Fill in the rest of the buffer --- */ |
| 100 | |
| 101 | h = o->ch->init(); |
| 102 | h->ops->hash(h, o->ep, o->epsz); |
| 103 | h->ops->done(h, mq); |
| 104 | h->ops->destroy(h); |
| 105 | pp = mq + hsz; |
| 106 | n = sz - 2 * hsz - msz - 1; |
| 107 | memset(pp, 0, n); |
| 108 | pp += n; |
| 109 | *pp++ = 1; |
| 110 | memcpy(pp, msg, msz); |
| 111 | |
| 112 | /* --- Do the packing --- */ |
| 113 | |
| 114 | n = sz - hsz; |
| 115 | c = o->cc->init(q, hsz); |
| 116 | c->ops->encrypt(c, mq, mq, n); |
| 117 | c->ops->destroy(c); |
| 118 | |
| 119 | c = o->cc->init(mq, n); |
| 120 | c->ops->encrypt(c, q, q, hsz); |
| 121 | c->ops->destroy(c); |
| 122 | |
| 123 | /* --- Done --- */ |
| 124 | |
| 125 | return (0); |
| 126 | } |
| 127 | |
| 128 | /* --- @oaep_decode@ --- * |
| 129 | * |
| 130 | * Arguments: @const void *buf@ = pointer to encoded buffer |
| 131 | * @size_t sz@ = size of the encoded buffer |
| 132 | * @dstr *d@ = pointer to destination string |
| 133 | * @void *p@ = pointer to OAEP parameter block |
| 134 | * |
| 135 | * Returns: The length of the output string if successful, negative on |
| 136 | * failure. |
| 137 | * |
| 138 | * Use: Implements the operation @EME-OAEP-DECODE@, as defined in |
| 139 | * PKCS#1 v. 2.0 (RFC2437). |
| 140 | */ |
| 141 | |
| 142 | int oaep_decode(const void *buf, size_t sz, dstr *d, void *p) |
| 143 | { |
| 144 | oaep *o = p; |
| 145 | gcipher *c; |
| 146 | ghash *h; |
| 147 | octet *q, *mq, *qq; |
| 148 | octet *pp; |
| 149 | size_t n; |
| 150 | size_t hsz = o->ch->hashsz; |
| 151 | int rc = -1; |
| 152 | |
| 153 | /* --- Ensure that the block is large enough --- */ |
| 154 | |
| 155 | if (sz < 2 * hsz) |
| 156 | return (-1); |
| 157 | |
| 158 | q = x_alloc(d->a, sz); |
| 159 | memcpy(q, buf, sz); |
| 160 | |
| 161 | /* --- Decrypt the message --- */ |
| 162 | |
| 163 | q++; sz--; |
| 164 | mq = q + hsz; |
| 165 | qq = q + sz; |
| 166 | n = sz - hsz; |
| 167 | c = o->cc->init(mq, n); |
| 168 | c->ops->decrypt(c, q, q, hsz); |
| 169 | c->ops->destroy(c); |
| 170 | |
| 171 | c = o->cc->init(q, hsz); |
| 172 | c->ops->decrypt(c, mq, mq, n); |
| 173 | c->ops->destroy(c); |
| 174 | q--; |
| 175 | |
| 176 | /* --- Check the hash on the encoding parameters --- */ |
| 177 | |
| 178 | h = o->ch->init(); |
| 179 | h->ops->hash(h, o->ep, o->epsz); |
| 180 | h->ops->done(h, q); |
| 181 | h->ops->destroy(h); |
| 182 | if ((memcmp(q, mq, hsz) != 0) || (*q != 0)) |
| 183 | goto fail; |
| 184 | |
| 185 | /* --- Now find the start of the actual message --- */ |
| 186 | |
| 187 | pp = mq + hsz; |
| 188 | while (*pp == 0 && pp < qq) |
| 189 | pp++; |
| 190 | if (pp >= qq || *pp++ != 1) |
| 191 | return (-1); |
| 192 | n = qq - pp; |
| 193 | dstr_putm(d, pp, n); |
| 194 | rc = n; |
| 195 | |
| 196 | fail: |
| 197 | x_free(d->a, q); |
| 198 | return (rc); |
| 199 | } |
| 200 | |
| 201 | /*----- Test rig ----------------------------------------------------------*/ |
| 202 | |
| 203 | #ifdef TEST_RIG |
| 204 | |
| 205 | #include <mLib/testrig.h> |
| 206 | |
| 207 | #include "rmd160.h" |
| 208 | #include "rmd160-mgf.h" |
| 209 | |
| 210 | typedef struct gctx { |
| 211 | grand r; |
| 212 | octet *buf; |
| 213 | } gctx; |
| 214 | |
| 215 | static void rfill(grand *r, void *buf, size_t sz) |
| 216 | { |
| 217 | gctx *g = (gctx *)r; |
| 218 | memcpy(buf, g->buf, sz); |
| 219 | } |
| 220 | |
| 221 | static const grand_ops gops = { |
| 222 | "const", 0, 0, |
| 223 | 0, 0, |
| 224 | 0, 0, 0, 0, rfill |
| 225 | }; |
| 226 | |
| 227 | static int verify(dstr *v) |
| 228 | { |
| 229 | gctx gr; |
| 230 | dstr d = DSTR_INIT; |
| 231 | oaep o; |
| 232 | int ok = 1; |
| 233 | |
| 234 | dstr_ensure(&d, v[3].len); |
| 235 | d.len = v[3].len; |
| 236 | gr.r.ops = &gops; |
| 237 | gr.buf = (octet *)v[2].buf; |
| 238 | |
| 239 | o.cc = &rmd160_mgf; |
| 240 | o.ch = &rmd160; |
| 241 | o.r = &gr.r; |
| 242 | o.ep = v[1].buf; |
| 243 | o.epsz = v[1].len; |
| 244 | |
| 245 | if (oaep_encode(v[0].buf, v[0].len, d.buf, d.len, &o) || |
| 246 | memcmp(d.buf, v[3].buf, d.len) != 0) { |
| 247 | ok = 0; |
| 248 | fputs("\nfailure in oaep_encode", stderr); |
| 249 | fputs("\n message = ", stderr); type_hex.dump(&v[0], stderr); |
| 250 | fputs("\n params = ", stderr); type_hex.dump(&v[1], stderr); |
| 251 | fputs("\n salt = ", stderr); type_hex.dump(&v[2], stderr); |
| 252 | fputs("\nexpected = ", stderr); type_hex.dump(&v[3], stderr); |
| 253 | fputs("\n output = ", stderr); type_hex.dump(&d, stderr); |
| 254 | fputc('\n', stderr); |
| 255 | } |
| 256 | |
| 257 | DRESET(&d); |
| 258 | if (oaep_decode(v[3].buf, v[3].len, &d, &o) < 0 || |
| 259 | d.len != v[0].len || memcmp(d.buf, v[0].buf, d.len) != 0) { |
| 260 | ok = 0; |
| 261 | fputs("\nfailure in oaep_decode", stderr); |
| 262 | fputs("\n goop = ", stderr); type_hex.dump(&v[3], stderr); |
| 263 | fputs("\n params = ", stderr); type_hex.dump(&v[1], stderr); |
| 264 | fputs("\n salt = ", stderr); type_hex.dump(&v[2], stderr); |
| 265 | fputs("\nexpected = ", stderr); type_hex.dump(&v[0], stderr); |
| 266 | fputs("\n output = ", stderr); type_hex.dump(&d, stderr); |
| 267 | fputc('\n', stderr); |
| 268 | } |
| 269 | |
| 270 | dstr_destroy(&d); |
| 271 | return (ok); |
| 272 | } |
| 273 | |
| 274 | static test_chunk tests[] = { |
| 275 | { "oaep", verify, { &type_hex, &type_hex, &type_hex, &type_hex, 0 } }, |
| 276 | { 0, 0, { 0 } } |
| 277 | }; |
| 278 | |
| 279 | int main(int argc, char *argv[]) |
| 280 | { |
| 281 | test_run(argc, argv, tests, SRCDIR "/tests/oaep"); |
| 282 | return (0); |
| 283 | } |
| 284 | |
| 285 | #endif |
| 286 | |
| 287 | /*----- That's all, folks -------------------------------------------------*/ |