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