3 * $Id: oaep.c,v 1.5 2002/01/13 20:20:39 mdw Exp $
5 * Optimal asymmetric encryption packing
7 * (c) 2000 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Revision history --------------------------------------------------*
33 * Revision 1.5 2002/01/13 20:20:39 mdw
34 * Hack the @oaep_decode@ code some more, to make it work again.
36 * Revision 1.4 2002/01/13 13:50:21 mdw
37 * Allow only one error return, to frustrate Manger's attack against OAEP.
39 * Revision 1.3 2001/02/22 09:04:39 mdw
42 * Revision 1.2 2000/07/15 10:01:48 mdw
43 * Test rig added, based on RIPEMD160-MGF1 test vectors.
45 * Revision 1.1 2000/07/01 11:18:30 mdw
46 * Support for Optimal Asymmetric Encryption Padding.
50 /*----- Header files ------------------------------------------------------*/
54 #include <mLib/alloc.h>
55 #include <mLib/bits.h>
56 #include <mLib/dstr.h>
63 /*----- Main code ---------------------------------------------------------*/
65 /* --- @oaep_encode@ --- *
67 * Arguments: @const void *msg@ = pointer to message data
68 * @size_t msz@ = size of message data
69 * @void *buf@ = pointer to output buffer
70 * @size_t sz@ = size of the output buffer
71 * @void *p@ = pointer to OAEP parameter block
73 * Returns: Zero if all went well, negative on failure.
75 * Use: Implements the operation @EME-OAEP-ENCODE@, as defined in
76 * PKCS#1 v. 2.0 (RFC2437).
79 int oaep_encode(const void *msg, size_t msz, void *buf, size_t sz, void *p)
82 size_t hsz = o->ch->hashsz;
89 /* --- Ensure that everything is sensibly sized --- */
91 if (2 * hsz + 2 + msz > sz)
94 /* --- Make the `seed' value --- */
100 o->r->ops->fill(o->r, q, hsz);
102 /* --- Fill in the rest of the buffer --- */
105 h->ops->hash(h, o->ep, o->epsz);
109 n = sz - 2 * hsz - msz - 1;
113 memcpy(pp, msg, msz);
115 /* --- Do the packing --- */
118 c = o->cc->init(q, hsz);
119 c->ops->encrypt(c, mq, mq, n);
122 c = o->cc->init(mq, n);
123 c->ops->encrypt(c, q, q, hsz);
131 /* --- @oaep_decode@ --- *
133 * Arguments: @const void *buf@ = pointer to encoded buffer
134 * @size_t sz@ = size of the encoded buffer
135 * @dstr *d@ = pointer to destination string
136 * @void *p@ = pointer to OAEP parameter block
138 * Returns: The length of the output string if successful, negative on
141 * Use: Implements the operation @EME-OAEP-DECODE@, as defined in
142 * PKCS#1 v. 2.0 (RFC2437).
145 int oaep_decode(const void *buf, size_t sz, dstr *d, void *p)
154 size_t hsz = o->ch->hashsz;
157 /* --- Ensure that the block is large enough --- */
162 q = x_alloc(d->a, sz);
165 /* --- Decrypt the message --- */
172 c = o->cc->init(mq, n);
173 c->ops->decrypt(c, q, q, hsz);
176 c = o->cc->init(q, hsz);
177 c->ops->decrypt(c, mq, mq, n);
181 /* --- Check the hash on the encoding parameters --- */
184 h->ops->hash(h, o->ep, o->epsz);
187 bad |= memcmp(q, mq, hsz);
189 /* --- Now find the start of the actual message --- */
192 while (*pp == 0 && pp < qq)
194 bad |= (pp >= qq) | (*pp++ != 1);
204 /*----- Test rig ----------------------------------------------------------*/
208 #include <mLib/testrig.h>
211 #include "rmd160-mgf.h"
213 typedef struct gctx {
218 static void rfill(grand *r, void *buf, size_t sz)
221 memcpy(buf, g->buf, sz);
224 static const grand_ops gops = {
230 static int verify(dstr *v)
237 dstr_ensure(&d, v[3].len);
240 gr.buf = (octet *)v[2].buf;
248 if (oaep_encode(v[0].buf, v[0].len, d.buf, d.len, &o) ||
249 memcmp(d.buf, v[3].buf, d.len) != 0) {
251 fputs("\nfailure in oaep_encode", stderr);
252 fputs("\n message = ", stderr); type_hex.dump(&v[0], stderr);
253 fputs("\n params = ", stderr); type_hex.dump(&v[1], stderr);
254 fputs("\n salt = ", stderr); type_hex.dump(&v[2], stderr);
255 fputs("\nexpected = ", stderr); type_hex.dump(&v[3], stderr);
256 fputs("\n output = ", stderr); type_hex.dump(&d, stderr);
261 if (oaep_decode(v[3].buf, v[3].len, &d, &o) < 0 ||
262 d.len != v[0].len || memcmp(d.buf, v[0].buf, d.len) != 0) {
264 fputs("\nfailure in oaep_decode", stderr);
265 fputs("\n goop = ", stderr); type_hex.dump(&v[3], stderr);
266 fputs("\n params = ", stderr); type_hex.dump(&v[1], stderr);
267 fputs("\n salt = ", stderr); type_hex.dump(&v[2], stderr);
268 fputs("\nexpected = ", stderr); type_hex.dump(&v[0], stderr);
269 fputs("\n output = ", stderr); type_hex.dump(&d, stderr);
277 static test_chunk tests[] = {
278 { "oaep", verify, { &type_hex, &type_hex, &type_hex, &type_hex, 0 } },
282 int main(int argc, char *argv[])
284 test_run(argc, argv, tests, SRCDIR "/tests/oaep");
290 /*----- That's all, folks -------------------------------------------------*/