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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: key-binary.c,v 1.5 2004/04/01 12:50:09 mdw Exp $ |
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4 | * |
5 | * Key binary encoding |
6 | * |
7 | * (c) 1999 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: key-binary.c,v $ |
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33 | * Revision 1.5 2004/04/01 12:50:09 mdw |
34 | * Add cyclic group abstraction, with test code. Separate off exponentation |
35 | * functions for better static linking. Fix a buttload of bugs on the way. |
36 | * Generally ensure that negative exponents do inversion correctly. Add |
37 | * table of standard prime-field subgroups. (Binary field subgroups are |
38 | * currently unimplemented but easy to add if anyone ever finds a good one.) |
39 | * |
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40 | * Revision 1.4 2004/03/28 01:58:47 mdw |
41 | * Generate, store and retreive elliptic curve keys. |
42 | * |
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43 | * Revision 1.3 2001/02/03 11:57:00 mdw |
44 | * Track mLib change: symbols no longer need to include a terminating |
45 | * null. |
46 | * |
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47 | * Revision 1.2 2000/06/17 11:25:20 mdw |
48 | * Use secure memory interface from MP library. |
49 | * |
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50 | * Revision 1.1 2000/02/12 18:21:02 mdw |
51 | * Overhaul of key management (again). |
52 | * |
53 | */ |
54 | |
55 | /*----- Header files ------------------------------------------------------*/ |
56 | |
57 | #include <stdlib.h> |
58 | #include <string.h> |
59 | |
60 | #include <mLib/bits.h> |
61 | #include <mLib/dstr.h> |
62 | #include <mLib/sub.h> |
63 | #include <mLib/sym.h> |
64 | |
65 | #include "key-data.h" |
66 | #include "mp.h" |
67 | #include "mptext.h" |
68 | |
69 | /*----- Main code ---------------------------------------------------------*/ |
70 | |
71 | /* --- @key_decode@ --- * |
72 | * |
73 | * Arguments: @const void *p@ = pointer to buffer to read |
74 | * @size_t sz@ = size of the buffer |
75 | * @key_data *k@ = pointer to key data block to write to |
76 | * |
77 | * Returns: Zero if everything worked, nonzero otherwise. |
78 | * |
79 | * Use: Decodes a binary representation of a key. |
80 | */ |
81 | |
82 | int key_decode(const void *p, size_t sz, key_data *k) |
83 | { |
84 | const octet *q = p; |
85 | size_t psz; |
86 | unsigned e; |
87 | |
88 | /* --- Parse the header information --- * |
89 | * |
90 | * Make sure the size matches external reality. Security holes have been |
91 | * known to creep in without this sort of check. (No, this isn't an after- |
92 | * the-fact patch-up.) |
93 | */ |
94 | |
95 | e = LOAD16(q); |
96 | psz = LOAD16(q + 2); |
97 | if (psz + 4 > sz) |
98 | return (-1); |
99 | k->e = e; |
100 | |
101 | /* --- Now decide what to do --- */ |
102 | |
103 | switch (e & KF_ENCMASK) { |
104 | |
105 | /* --- Plain binary data --- */ |
106 | |
107 | case KENC_BINARY: |
108 | case KENC_ENCRYPT: |
109 | k->u.k.k = sub_alloc(psz); |
110 | memcpy(k->u.k.k, q + 4, psz); |
111 | k->u.k.sz = psz; |
112 | break; |
113 | |
114 | /* --- Multiprecision integer data --- */ |
115 | |
116 | case KENC_MP: |
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117 | k->u.m = mp_loadb(k->e & KF_BURN ? MP_NEWSEC : MP_NEW, q + 4, psz); |
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118 | break; |
119 | |
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120 | /* --- String data --- */ |
121 | |
122 | case KENC_STRING: |
123 | k->u.p = xmalloc(sz + 1); |
124 | memcpy(k->u.p, q + 4, sz); |
125 | k->u.p[sz] = 0; |
126 | break; |
127 | |
128 | /* --- Elliptic curve point data --- */ |
129 | |
130 | case KENC_EC: { |
131 | size_t xsz, ysz; |
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132 | EC_CREATE(&k->u.e); |
133 | if (!sz) break; |
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134 | if (sz < 2) return (-1); |
135 | xsz = LOAD16(q + 4); |
136 | if (sz < xsz + 4) return (-1); |
137 | ysz = LOAD16(q + 6 + xsz); |
138 | if (sz < xsz + ysz + 4) return (-1); |
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139 | k->u.e.x = mp_loadb(MP_NEW, q + 6, xsz); |
140 | k->u.e.y = mp_loadb(MP_NEW, q + 6 + xsz, ysz); |
141 | } break; |
142 | |
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143 | /* --- Structured key data --- */ |
144 | |
145 | case KENC_STRUCT: { |
146 | dstr d = DSTR_INIT; |
147 | key_struct *ks; |
148 | unsigned f; |
149 | |
150 | if ((k->e & ~KF_ENCMASK) || (psz & 3)) |
151 | return (-1); |
152 | q += 4; |
153 | sym_create(&k->u.s); |
154 | |
155 | while (psz) { |
156 | |
157 | /* --- Read the tag string --- */ |
158 | |
159 | DRESET(&d); |
160 | sz = LOAD8(q); |
161 | if (sz >= psz) |
162 | goto fail; |
163 | DPUTM(&d, q + 1, sz); |
164 | DPUTZ(&d); |
165 | sz = (sz + 4) & ~3; |
166 | q += sz; psz -= sz; |
167 | |
168 | /* --- Read the encoding and size --- */ |
169 | |
170 | e = LOAD16(q); |
171 | sz = (LOAD16(q + 2) + 7) & ~3; |
172 | if (sz > psz) |
173 | goto fail; |
174 | |
175 | /* --- Create a table node and fill it in --- */ |
176 | |
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177 | ks = sym_find(&k->u.s, d.buf, d.len, sizeof(*ks), &f); |
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178 | if (f) |
179 | goto fail; |
180 | if (key_decode(q, sz, &ks->k)) { |
181 | sym_remove(&k->u.s, ks); |
182 | goto fail; |
183 | } |
184 | psz -= sz; |
185 | q += sz; |
186 | } |
187 | dstr_destroy(&d); |
188 | break; |
189 | |
190 | /* --- Tidy up after a failure --- */ |
191 | |
192 | fail: |
193 | dstr_destroy(&d); |
194 | key_destroy(k); |
195 | return (-1); |
196 | } break; |
197 | |
198 | /* --- Everything else --- */ |
199 | |
200 | default: |
201 | return (-1); |
202 | } |
203 | |
204 | /* --- OK, that was good --- */ |
205 | |
206 | return (0); |
207 | } |
208 | |
209 | /* --- @key_encode@ --- * |
210 | * |
211 | * Arguments: @key_data *k@ = pointer to key data block |
212 | * @dstr *d@ = pointer to destination string |
213 | * @const key_filter *kf@ = pointer to key selection block |
214 | * |
215 | * Returns: Nonzero if an item was actually written. |
216 | * |
217 | * Use: Encodes a key block as binary data. |
218 | */ |
219 | |
220 | int key_encode(key_data *k, dstr *d, const key_filter *kf) |
221 | { |
222 | int rc = 0; |
223 | if (!KEY_MATCH(k, kf)) |
224 | return (0); |
225 | switch (k->e & KF_ENCMASK) { |
226 | case KENC_BINARY: |
227 | case KENC_ENCRYPT: { |
228 | char *p; |
229 | |
230 | DENSURE(d, (k->u.k.sz + 7) & ~3); |
231 | p = d->buf + d->len; |
232 | STORE16(p, k->e); |
233 | STORE16(p + 2, k->u.k.sz); |
234 | d->len += 4; |
235 | DPUTM(d, k->u.k.k, k->u.k.sz); |
236 | rc = 1; |
237 | } break; |
238 | |
239 | case KENC_MP: { |
240 | char *p; |
241 | size_t sz = mp_octets(k->u.m); |
242 | |
243 | DENSURE(d, (sz + 7) & ~3); |
244 | p = d->buf + d->len; |
245 | STORE16(p, k->e); |
246 | STORE16(p + 2, sz); |
247 | mp_storeb(k->u.m, p + 4, sz); |
248 | d->len += sz + 4; |
249 | rc = 1; |
250 | } break; |
251 | |
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252 | case KENC_STRING: { |
253 | char *p; |
254 | size_t sz = strlen(k->u.p); |
255 | |
256 | DENSURE(d, (sz + 7) & ~3); |
257 | p = d->buf + d->len; |
258 | STORE16(p, k->e); |
259 | STORE16(p + 2, sz); |
260 | memcpy(p + 4, k->u.p, sz); |
261 | d->len += sz + 4; |
262 | rc = 1; |
263 | } break; |
264 | |
265 | case KENC_EC: { |
266 | char *p; |
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267 | size_t xsz, ysz; |
268 | size_t sz; |
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269 | |
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270 | if (EC_ATINF(&k->u.e)) |
271 | sz = 0; |
272 | else { |
273 | xsz = mp_octets(k->u.e.x); |
274 | ysz = mp_octets(k->u.e.y); |
275 | sz = xsz + ysz + 4; |
276 | } |
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277 | DENSURE(d, (sz + 7) & ~3); |
278 | p = d->buf + d->len; |
279 | STORE16(p, k->e); |
280 | STORE16(p + 2, sz); |
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281 | if (!EC_ATINF(&k->u.e)) { |
282 | STORE16(p + 4, xsz); |
283 | mp_storeb(k->u.e.x, p + 6, xsz); |
284 | STORE16(p + 6 + xsz, ysz); |
285 | mp_storeb(k->u.e.y, p + 8 + xsz, ysz); |
286 | } |
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287 | d->len += sz + 4; |
288 | rc = 1; |
289 | } break; |
290 | |
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291 | case KENC_STRUCT: { |
292 | size_t n; |
293 | char *p; |
294 | key_struct *ks; |
295 | sym_iter i; |
296 | |
297 | n = d->len; |
298 | DENSURE(d, 4); |
299 | p = d->buf + n; |
300 | STORE16(p, k->e & KF_ENCMASK); |
301 | d->len += 4; |
302 | for (sym_mkiter(&i, &k->u.s); (ks = sym_next(&i)) != 0; ) { |
303 | size_t o = d->len; |
304 | DENSURE(d, 1); |
305 | *(octet *)(d->buf + d->len++) = strlen(SYM_NAME(ks)); |
306 | DPUTS(d, SYM_NAME(ks)); |
307 | while (d->len & 3) |
308 | DPUTC(d, 0); |
309 | if (key_encode(&ks->k, d, kf)) |
310 | rc = 1; |
311 | else |
312 | d->len = o; |
313 | } |
314 | if (!rc) |
315 | d->len = n; |
316 | else { |
317 | p = d->buf + n + 2; |
318 | n = d->len - n - 4; |
319 | STORE16(p, n); |
320 | } |
321 | } break; |
322 | } |
323 | while (d->len & 3) |
324 | DPUTC(d, 0); |
325 | return (rc); |
326 | } |
327 | |
328 | /*----- That's all, folks -------------------------------------------------*/ |