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410c8acf | 1 | /* -*-c-*- |
2 | * | |
410c8acf | 3 | * Handling of symmetric keysets |
4 | * | |
5 | * (c) 2001 Straylight/Edgeware | |
6 | */ | |
7 | ||
e04c2d50 | 8 | /*----- Licensing notice --------------------------------------------------* |
410c8acf | 9 | * |
10 | * This file is part of Trivial IP Encryption (TrIPE). | |
11 | * | |
12 | * TrIPE is free software; you can redistribute it and/or modify | |
13 | * it under the terms of the GNU General Public License as published by | |
14 | * the Free Software Foundation; either version 2 of the License, or | |
15 | * (at your option) any later version. | |
e04c2d50 | 16 | * |
410c8acf | 17 | * TrIPE is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
e04c2d50 | 21 | * |
410c8acf | 22 | * You should have received a copy of the GNU General Public License |
23 | * along with TrIPE; if not, write to the Free Software Foundation, | |
24 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
25 | */ | |
26 | ||
410c8acf | 27 | /*----- Header files ------------------------------------------------------*/ |
28 | ||
29 | #include "tripe.h" | |
30 | ||
410c8acf | 31 | /*----- Handy macros ------------------------------------------------------*/ |
32 | ||
33 | #define KEYOK(ks, now) ((ks)->sz_exp > 0 && (ks)->t_exp > now) | |
34 | ||
b5c45da1 | 35 | #define SEQSZ 4 /* Size of sequence number packet */ |
36 | ||
426c0bc6 | 37 | /*----- Low-level packet encryption and decryption ------------------------*/ |
410c8acf | 38 | |
59d670e7 | 39 | /* --- Encrypted data format --- * |
40 | * | |
7ed14135 | 41 | * Let %$p_i$% be the %$i$%-th plaintext message, with type %$t$%. We first |
e04c2d50 | 42 | * compute |
59d670e7 | 43 | * |
44 | * %$c_i = \mathcal{E}\textrm{-CBC}_{K_{\text{E}}}(p_i)$% | |
45 | * | |
46 | * as the CBC-ciphertext of %$p_i$%, and then | |
47 | * | |
7ed14135 | 48 | * %$\sigma_i = \mathcal{T}_{K_{\text{M}}}(t, i, c_i)$% |
59d670e7 | 49 | * |
50 | * as a MAC on the %%\emph{ciphertext}%%. The message sent is then the pair | |
51 | * %$(\sigma_i, c_i)$%. This construction is provably secure in the NM-CCA | |
52 | * sense (assuming that the cipher is IND-CPA, and the MAC is SUF-CMA) | |
53 | * [Bellare and Namprempre]. | |
54 | * | |
55 | * This also ensures that, assuming the key is good, we have a secure channel | |
56 | * [Krawczyk]. Actually, [Krawczyk] shows that, if the cipher is either a | |
57 | * simple stream cipher or a block cipher in CBC mode, we can use the MAC- | |
58 | * then-encrypt scheme and still have a secure channel. However, I like the | |
59 | * NM-CCA guarantee from [Bellare and Namprempre]. I'm less worried about | |
60 | * the Horton Principle [Wagner and Schneier]. | |
61 | */ | |
62 | ||
426c0bc6 | 63 | /* --- @doencrypt@ --- * |
410c8acf | 64 | * |
426c0bc6 | 65 | * Arguments: @keyset *ks@ = pointer to keyset to use |
7ed14135 | 66 | * @unsigned ty@ = type of message this is |
426c0bc6 | 67 | * @buf *b@ = pointer to an input buffer |
68 | * @buf *bb@ = pointer to an output buffer | |
410c8acf | 69 | * |
a50f9a0e MW |
70 | * Returns: Zero if OK; @KSERR_REGEN@ if it's time to generate new keys. |
71 | * Also returns zero if there was insufficient buffer space, but | |
72 | * the buffer is broken in this case. | |
410c8acf | 73 | * |
426c0bc6 | 74 | * Use: Encrypts a message with the given key. We assume that the |
75 | * keyset is OK to use. | |
410c8acf | 76 | */ |
77 | ||
7ed14135 | 78 | static int doencrypt(keyset *ks, unsigned ty, buf *b, buf *bb) |
410c8acf | 79 | { |
426c0bc6 | 80 | ghash *h; |
b5c45da1 | 81 | gcipher *c = ks->cout; |
426c0bc6 | 82 | const octet *p = BCUR(b); |
83 | size_t sz = BLEFT(b); | |
59d670e7 | 84 | octet *qmac, *qseq, *qiv, *qpk; |
426c0bc6 | 85 | uint32 oseq; |
b5c45da1 | 86 | size_t ivsz = GC_CLASS(c)->blksz; |
87 | size_t tagsz = ks->tagsz; | |
426c0bc6 | 88 | size_t osz, nsz; |
7ed14135 | 89 | octet t[4]; |
426c0bc6 | 90 | int rc = 0; |
91 | ||
92 | /* --- Allocate the required buffer space --- */ | |
93 | ||
b5c45da1 | 94 | if (buf_ensure(bb, tagsz + SEQSZ + ivsz + sz)) |
426c0bc6 | 95 | return (0); /* Caution! */ |
b5c45da1 | 96 | qmac = BCUR(bb); qseq = qmac + tagsz; qiv = qseq + SEQSZ; qpk = qiv + ivsz; |
97 | BSTEP(bb, tagsz + SEQSZ + ivsz + sz); | |
7ed14135 | 98 | STORE32(t, ty); |
426c0bc6 | 99 | |
426c0bc6 | 100 | oseq = ks->oseq++; STORE32(qseq, oseq); |
426c0bc6 | 101 | IF_TRACING(T_KEYSET, { |
102 | trace(T_KEYSET, "keyset: encrypting packet %lu using keyset %u", | |
103 | (unsigned long)oseq, ks->seq); | |
b5c45da1 | 104 | trace_block(T_CRYPTO, "crypto: plaintext packet", p, sz); |
426c0bc6 | 105 | }) |
59d670e7 | 106 | |
b5c45da1 | 107 | /* --- Encrypt the packet --- */ |
59d670e7 | 108 | |
b5c45da1 | 109 | if (ivsz) { |
110 | rand_get(RAND_GLOBAL, qiv, ivsz); | |
111 | GC_SETIV(c, qiv); | |
112 | IF_TRACING(T_KEYSET, { | |
113 | trace_block(T_CRYPTO, "crypto: initialization vector", qiv, ivsz); | |
114 | }) | |
115 | } | |
116 | GC_ENCRYPT(c, p, qpk, sz); | |
426c0bc6 | 117 | IF_TRACING(T_KEYSET, { |
b5c45da1 | 118 | trace_block(T_CRYPTO, "crypto: encrypted packet", qpk, sz); |
426c0bc6 | 119 | }) |
120 | ||
b5c45da1 | 121 | /* --- Now compute the MAC --- */ |
122 | ||
123 | if (tagsz) { | |
124 | h = GM_INIT(ks->mout); | |
125 | GH_HASH(h, t, sizeof(t)); | |
126 | GH_HASH(h, qseq, SEQSZ + ivsz + sz); | |
127 | memcpy(qmac, GH_DONE(h, 0), tagsz); | |
128 | GH_DESTROY(h); | |
129 | IF_TRACING(T_KEYSET, { | |
130 | trace_block(T_CRYPTO, "crypto: computed MAC", qmac, tagsz); | |
131 | }) | |
132 | } | |
133 | ||
426c0bc6 | 134 | /* --- Deduct the packet size from the key's data life --- */ |
135 | ||
136 | osz = ks->sz_exp; | |
137 | if (osz > sz) | |
138 | nsz = osz - sz; | |
139 | else | |
140 | nsz = 0; | |
383a9d71 | 141 | if (osz >= ks->sz_regen && ks->sz_regen > nsz) { |
426c0bc6 | 142 | T( trace(T_KEYSET, "keyset: keyset %u data regen limit exceeded -- " |
143 | "forcing exchange", ks->seq); ) | |
a50f9a0e | 144 | rc = KSERR_REGEN; |
426c0bc6 | 145 | } |
146 | ks->sz_exp = nsz; | |
e04c2d50 | 147 | return (rc); |
410c8acf | 148 | } |
149 | ||
426c0bc6 | 150 | /* --- @dodecrypt@ --- * |
410c8acf | 151 | * |
426c0bc6 | 152 | * Arguments: @keyset *ks@ = pointer to keyset to use |
7ed14135 | 153 | * @unsigned ty@ = expected type code |
426c0bc6 | 154 | * @buf *b@ = pointer to an input buffer |
155 | * @buf *bb@ = pointer to an output buffer | |
156 | * @uint32 *seq@ = where to store the sequence number | |
410c8acf | 157 | * |
a50f9a0e | 158 | * Returns: Zero on success; @KSERR_DECRYPT@ on failure. |
410c8acf | 159 | * |
426c0bc6 | 160 | * Use: Attempts to decrypt a message with the given key. No other |
161 | * checking (e.g., sequence number checks) is performed. We | |
162 | * assume that the keyset is OK to use, and that there is | |
163 | * sufficient output buffer space reserved. If the decryption | |
164 | * is successful, the buffer pointer is moved past the decrypted | |
165 | * packet, and the packet's sequence number is stored in @*seq@. | |
410c8acf | 166 | */ |
167 | ||
7ed14135 | 168 | static int dodecrypt(keyset *ks, unsigned ty, buf *b, buf *bb, uint32 *seq) |
410c8acf | 169 | { |
59d670e7 | 170 | const octet *pmac, *piv, *pseq, *ppk; |
426c0bc6 | 171 | size_t psz = BLEFT(b); |
172 | size_t sz; | |
173 | octet *q = BCUR(bb); | |
174 | ghash *h; | |
175 | gcipher *c = ks->cin; | |
b5c45da1 | 176 | size_t ivsz = GC_CLASS(c)->blksz; |
177 | size_t tagsz = ks->tagsz; | |
426c0bc6 | 178 | octet *mac; |
179 | int eq; | |
7ed14135 | 180 | octet t[4]; |
426c0bc6 | 181 | |
182 | /* --- Break up the packet into its components --- */ | |
183 | ||
b5c45da1 | 184 | if (psz < ivsz + SEQSZ + tagsz) { |
426c0bc6 | 185 | T( trace(T_KEYSET, "keyset: block too small for keyset %u", ks->seq); ) |
12a26b8b | 186 | return (KSERR_MALFORMED); |
410c8acf | 187 | } |
b5c45da1 | 188 | sz = psz - ivsz - SEQSZ - tagsz; |
189 | pmac = BCUR(b); pseq = pmac + tagsz; piv = pseq + SEQSZ; ppk = piv + ivsz; | |
7ed14135 | 190 | STORE32(t, ty); |
426c0bc6 | 191 | |
426c0bc6 | 192 | IF_TRACING(T_KEYSET, { |
193 | trace(T_KEYSET, "keyset: decrypting using keyset %u", ks->seq); | |
b5c45da1 | 194 | trace_block(T_CRYPTO, "crypto: ciphertext packet", ppk, sz); |
426c0bc6 | 195 | }) |
b5c45da1 | 196 | |
197 | /* --- Verify the MAC on the packet --- */ | |
198 | ||
199 | if (tagsz) { | |
200 | h = GM_INIT(ks->min); | |
201 | GH_HASH(h, t, sizeof(t)); | |
202 | GH_HASH(h, pseq, SEQSZ + ivsz + sz); | |
203 | mac = GH_DONE(h, 0); | |
04ed79b8 | 204 | eq = ct_memeq(mac, pmac, tagsz); |
426c0bc6 | 205 | IF_TRACING(T_KEYSET, { |
b5c45da1 | 206 | trace_block(T_CRYPTO, "crypto: computed MAC", mac, tagsz); |
426c0bc6 | 207 | }) |
b5c45da1 | 208 | GH_DESTROY(h); |
209 | if (!eq) { | |
210 | IF_TRACING(T_KEYSET, { | |
211 | trace(T_KEYSET, "keyset: incorrect MAC: decryption failed"); | |
212 | trace_block(T_CRYPTO, "crypto: expected MAC", pmac, tagsz); | |
213 | }) | |
a50f9a0e | 214 | return (KSERR_DECRYPT); |
b5c45da1 | 215 | } |
426c0bc6 | 216 | } |
59d670e7 | 217 | |
218 | /* --- Decrypt the packet --- */ | |
219 | ||
b5c45da1 | 220 | if (ivsz) { |
221 | GC_SETIV(c, piv); | |
222 | IF_TRACING(T_KEYSET, { | |
223 | trace_block(T_CRYPTO, "crypto: initialization vector", piv, ivsz); | |
224 | }) | |
225 | } | |
226 | GC_DECRYPT(c, ppk, q, sz); | |
426c0bc6 | 227 | if (seq) |
228 | *seq = LOAD32(pseq); | |
229 | IF_TRACING(T_KEYSET, { | |
230 | trace(T_KEYSET, "keyset: decrypted OK (sequence = %lu)", | |
231 | (unsigned long)LOAD32(pseq)); | |
232 | trace_block(T_CRYPTO, "crypto: decrypted packet", q, sz); | |
233 | }) | |
234 | BSTEP(bb, sz); | |
235 | return (0); | |
410c8acf | 236 | } |
237 | ||
426c0bc6 | 238 | /*----- Operations on a single keyset -------------------------------------*/ |
239 | ||
240 | /* --- @ks_drop@ --- * | |
241 | * | |
242 | * Arguments: @keyset *ks@ = pointer to a keyset | |
243 | * | |
244 | * Returns: --- | |
245 | * | |
246 | * Use: Decrements a keyset's reference counter. If the counter hits | |
247 | * zero, the keyset is freed. | |
248 | */ | |
249 | ||
250 | void ks_drop(keyset *ks) | |
251 | { | |
252 | if (--ks->ref) | |
253 | return; | |
b5c45da1 | 254 | GC_DESTROY(ks->cin); |
255 | GC_DESTROY(ks->cout); | |
256 | GM_DESTROY(ks->min); | |
257 | GM_DESTROY(ks->mout); | |
426c0bc6 | 258 | DESTROY(ks); |
410c8acf | 259 | } |
260 | ||
261 | /* --- @ks_gen@ --- * | |
262 | * | |
426c0bc6 | 263 | * Arguments: @const void *k@ = pointer to key material |
264 | * @size_t x, y, z@ = offsets into key material (see below) | |
e04c2d50 | 265 | * @peer *p@ = pointer to peer information |
410c8acf | 266 | * |
426c0bc6 | 267 | * Returns: A pointer to the new keyset. |
410c8acf | 268 | * |
426c0bc6 | 269 | * Use: Derives a new keyset from the given key material. The |
270 | * offsets @x@, @y@ and @z@ separate the key material into three | |
271 | * parts. Between the @k@ and @k + x@ is `my' contribution to | |
272 | * the key material; between @k + x@ and @k + y@ is `your' | |
273 | * contribution; and between @k + y@ and @k + z@ is a shared | |
274 | * value we made together. These are used to construct two | |
275 | * pairs of symmetric keys. Each pair consists of an encryption | |
276 | * key and a message authentication key. One pair is used for | |
277 | * outgoing messages, the other for incoming messages. | |
278 | * | |
279 | * The new key is marked so that it won't be selected for output | |
280 | * by @ksl_encrypt@. You can still encrypt data with it by | |
281 | * calling @ks_encrypt@ directly. | |
410c8acf | 282 | */ |
283 | ||
9466fafa | 284 | keyset *ks_gen(const void *k, size_t x, size_t y, size_t z, peer *p) |
410c8acf | 285 | { |
b5c45da1 | 286 | ghash *h; |
287 | const octet *hh; | |
410c8acf | 288 | keyset *ks = CREATE(keyset); |
289 | time_t now = time(0); | |
9466fafa | 290 | const octet *pp = k; |
35c8b547 | 291 | const algswitch *algs = &p->kx.kpriv->algs; |
410c8acf | 292 | T( static unsigned seq = 0; ) |
293 | ||
294 | T( trace(T_KEYSET, "keyset: adding new keyset %u", seq); ) | |
295 | ||
426c0bc6 | 296 | /* --- Construct the various keys --- * |
297 | * | |
298 | * This is done with macros, because it's quite tedious. | |
299 | */ | |
300 | ||
b5c45da1 | 301 | #define MINE GH_HASH(h, pp, x) |
302 | #define YOURS GH_HASH(h, pp + x, y - x) | |
303 | #define OURS GH_HASH(h, pp + y, z - y) | |
304 | ||
305 | #define HASH_in MINE; YOURS; OURS | |
306 | #define HASH_out YOURS; MINE; OURS | |
35c8b547 MW |
307 | #define INIT_c(k) GC_INIT(algs->c, (k), algs->cksz) |
308 | #define INIT_m(k) GM_KEY(algs->m, (k), algs->mksz) | |
b5c45da1 | 309 | #define STR_c "encryption" |
310 | #define STR_m "integrity" | |
311 | #define STR_in "incoming" | |
312 | #define STR_out "outgoing" | |
313 | ||
314 | #define SETKEY(a, dir) do { \ | |
35c8b547 | 315 | h = GH_INIT(algs->h); \ |
b5c45da1 | 316 | HASH_STRING(h, "tripe-" STR_##a); \ |
317 | HASH_##dir; \ | |
318 | hh = GH_DONE(h, 0); \ | |
410c8acf | 319 | IF_TRACING(T_KEYSET, { \ |
b5c45da1 | 320 | trace_block(T_CRYPTO, "crypto: " STR_##dir " key " STR_##a, \ |
35c8b547 | 321 | hh, algs->a##ksz); \ |
410c8acf | 322 | }) \ |
b5c45da1 | 323 | ks->a##dir = INIT_##a(hh); \ |
324 | GH_DESTROY(h); \ | |
410c8acf | 325 | } while (0) |
326 | ||
b5c45da1 | 327 | SETKEY(c, in); SETKEY(c, out); |
328 | SETKEY(m, in); SETKEY(m, out); | |
426c0bc6 | 329 | |
330 | #undef MINE | |
331 | #undef YOURS | |
332 | #undef OURS | |
b5c45da1 | 333 | #undef STR_c |
334 | #undef STR_m | |
335 | #undef STR_in | |
336 | #undef STR_out | |
337 | #undef INIT_c | |
338 | #undef INIT_m | |
339 | #undef HASH_in | |
340 | #undef HASH_out | |
341 | #undef SETKEY | |
410c8acf | 342 | |
343 | T( ks->seq = seq++; ) | |
e945d6e4 | 344 | ks->ref = 1; |
426c0bc6 | 345 | ks->t_exp = now + T_EXP; |
35c8b547 MW |
346 | ks->sz_exp = algs->expsz; |
347 | ks->sz_regen = algs->expsz/2; | |
37941236 | 348 | ks->oseq = 0; |
349 | seq_reset(&ks->iseq); | |
426c0bc6 | 350 | ks->next = 0; |
9466fafa | 351 | ks->p = p; |
426c0bc6 | 352 | ks->f = KSF_LISTEN; |
35c8b547 | 353 | ks->tagsz = algs->tagsz; |
426c0bc6 | 354 | return (ks); |
355 | } | |
356 | ||
426c0bc6 | 357 | /* --- @ks_activate@ --- * |
358 | * | |
359 | * Arguments: @keyset *ks@ = pointer to a keyset | |
360 | * | |
361 | * Returns: --- | |
362 | * | |
363 | * Use: Activates a keyset, so that it can be used for encrypting | |
364 | * outgoing messages. | |
365 | */ | |
366 | ||
367 | void ks_activate(keyset *ks) | |
368 | { | |
369 | if (ks->f & KSF_LISTEN) { | |
370 | T( trace(T_KEYSET, "keyset: activating keyset %u", ks->seq); ) | |
371 | ks->f &= ~KSF_LISTEN; | |
372 | } | |
410c8acf | 373 | } |
374 | ||
375 | /* --- @ks_encrypt@ --- * | |
376 | * | |
426c0bc6 | 377 | * Arguments: @keyset *ks@ = pointer to a keyset |
7ed14135 | 378 | * @unsigned ty@ = message type |
426c0bc6 | 379 | * @buf *b@ = pointer to input buffer |
380 | * @buf *bb@ = pointer to output buffer | |
381 | * | |
a50f9a0e MW |
382 | * Returns: Zero if successful; @KSERR_REGEN@ if we should negotiate a |
383 | * new key; @KSERR_NOKEYS@ if the key is not usable. Also | |
384 | * returns zero if there was insufficient buffer (but the output | |
385 | * buffer is broken in this case). | |
426c0bc6 | 386 | * |
387 | * Use: Encrypts a block of data using the key. Note that the `key | |
388 | * ought to be replaced' notification is only ever given once | |
389 | * for each key. Also note that this call forces a keyset to be | |
390 | * used even if it's marked as not for data output. | |
391 | */ | |
392 | ||
7ed14135 | 393 | int ks_encrypt(keyset *ks, unsigned ty, buf *b, buf *bb) |
426c0bc6 | 394 | { |
395 | time_t now = time(0); | |
396 | ||
397 | if (!KEYOK(ks, now)) { | |
398 | buf_break(bb); | |
a50f9a0e | 399 | return (KSERR_NOKEYS); |
426c0bc6 | 400 | } |
7ed14135 | 401 | return (doencrypt(ks, ty, b, bb)); |
426c0bc6 | 402 | } |
403 | ||
404 | /* --- @ks_decrypt@ --- * | |
405 | * | |
406 | * Arguments: @keyset *ks@ = pointer to a keyset | |
7ed14135 | 407 | * @unsigned ty@ = expected type code |
426c0bc6 | 408 | * @buf *b@ = pointer to an input buffer |
409 | * @buf *bb@ = pointer to an output buffer | |
410 | * | |
12a26b8b | 411 | * Returns: Zero on success; @KSERR_...@ on failure. Also returns |
a50f9a0e MW |
412 | * zero if there was insufficient buffer (but the output buffer |
413 | * is broken in this case). | |
426c0bc6 | 414 | * |
415 | * Use: Attempts to decrypt a message using a given key. Note that | |
416 | * requesting decryption with a key directly won't clear a | |
417 | * marking that it's not for encryption. | |
418 | */ | |
419 | ||
7ed14135 | 420 | int ks_decrypt(keyset *ks, unsigned ty, buf *b, buf *bb) |
426c0bc6 | 421 | { |
422 | time_t now = time(0); | |
423 | uint32 seq; | |
12a26b8b | 424 | int err; |
426c0bc6 | 425 | |
12a26b8b MW |
426 | if (!KEYOK(ks, now)) return (KSERR_DECRYPT); |
427 | if (buf_ensure(bb, BLEN(b))) return (0); | |
428 | if ((err = dodecrypt(ks, ty, b, bb, &seq)) != 0) return (err); | |
429 | if (seq_check(&ks->iseq, seq, "SYMM")) return (KSERR_SEQ); | |
426c0bc6 | 430 | return (0); |
431 | } | |
432 | ||
433 | /*----- Keyset list handling ----------------------------------------------*/ | |
434 | ||
435 | /* --- @ksl_free@ --- * | |
436 | * | |
437 | * Arguments: @keyset **ksroot@ = pointer to keyset list head | |
438 | * | |
439 | * Returns: --- | |
440 | * | |
441 | * Use: Frees (releases references to) all of the keys in a keyset. | |
442 | */ | |
443 | ||
444 | void ksl_free(keyset **ksroot) | |
445 | { | |
446 | keyset *ks, *ksn; | |
447 | for (ks = *ksroot; ks; ks = ksn) { | |
448 | ksn = ks->next; | |
449 | ks->f &= ~KSF_LINK; | |
450 | ks_drop(ks); | |
451 | } | |
452 | } | |
453 | ||
454 | /* --- @ksl_link@ --- * | |
455 | * | |
456 | * Arguments: @keyset **ksroot@ = pointer to keyset list head | |
457 | * @keyset *ks@ = pointer to a keyset | |
458 | * | |
459 | * Returns: --- | |
460 | * | |
461 | * Use: Links a keyset into a list. A keyset can only be on one list | |
462 | * at a time. Bad things happen otherwise. | |
463 | */ | |
464 | ||
465 | void ksl_link(keyset **ksroot, keyset *ks) | |
466 | { | |
467 | assert(!(ks->f & KSF_LINK)); | |
468 | ks->next = *ksroot; | |
469 | *ksroot = ks; | |
470 | ks->f |= KSF_LINK; | |
471 | ks->ref++; | |
472 | } | |
473 | ||
474 | /* --- @ksl_prune@ --- * | |
475 | * | |
476 | * Arguments: @keyset **ksroot@ = pointer to keyset list head | |
477 | * | |
478 | * Returns: --- | |
479 | * | |
480 | * Use: Prunes the keyset list by removing keys which mustn't be used | |
481 | * any more. | |
482 | */ | |
483 | ||
484 | void ksl_prune(keyset **ksroot) | |
485 | { | |
486 | time_t now = time(0); | |
487 | ||
488 | while (*ksroot) { | |
489 | keyset *ks = *ksroot; | |
490 | ||
491 | if (ks->t_exp <= now) { | |
492 | T( trace(T_KEYSET, "keyset: expiring keyset %u (time limit reached)", | |
493 | ks->seq); ) | |
494 | goto kill; | |
495 | } else if (ks->sz_exp == 0) { | |
496 | T( trace(T_KEYSET, "keyset: expiring keyset %u (data limit reached)", | |
497 | ks->seq); ) | |
498 | goto kill; | |
499 | } else { | |
500 | ksroot = &ks->next; | |
501 | continue; | |
502 | } | |
503 | ||
504 | kill: | |
505 | *ksroot = ks->next; | |
506 | ks->f &= ~KSF_LINK; | |
507 | ks_drop(ks); | |
508 | } | |
509 | } | |
510 | ||
511 | /* --- @ksl_encrypt@ --- * | |
512 | * | |
410c8acf | 513 | * Arguments: @keyset **ksroot@ = pointer to keyset list head |
7ed14135 | 514 | * @unsigned ty@ = message type |
410c8acf | 515 | * @buf *b@ = pointer to input buffer |
516 | * @buf *bb@ = pointer to output buffer | |
517 | * | |
a50f9a0e MW |
518 | * Returns: Zero if successful; @KSERR_REGEN@ if it's time to negotiate a |
519 | * new key; @KSERR_NOKEYS@ if there are no suitable keys | |
520 | * available. Also returns zero if there was insufficient | |
521 | * buffer space (but the output buffer is broken in this case). | |
410c8acf | 522 | * |
523 | * Use: Encrypts a packet. | |
524 | */ | |
525 | ||
7ed14135 | 526 | int ksl_encrypt(keyset **ksroot, unsigned ty, buf *b, buf *bb) |
410c8acf | 527 | { |
528 | time_t now = time(0); | |
426c0bc6 | 529 | keyset *ks = *ksroot; |
410c8acf | 530 | |
410c8acf | 531 | for (;;) { |
532 | if (!ks) { | |
426c0bc6 | 533 | T( trace(T_KEYSET, "keyset: no suitable keysets found"); ) |
410c8acf | 534 | buf_break(bb); |
a50f9a0e | 535 | return (KSERR_NOKEYS); |
410c8acf | 536 | } |
426c0bc6 | 537 | if (KEYOK(ks, now) && !(ks->f & KSF_LISTEN)) |
410c8acf | 538 | break; |
539 | ks = ks->next; | |
540 | } | |
541 | ||
7ed14135 | 542 | return (doencrypt(ks, ty, b, bb)); |
410c8acf | 543 | } |
544 | ||
426c0bc6 | 545 | /* --- @ksl_decrypt@ --- * |
410c8acf | 546 | * |
547 | * Arguments: @keyset **ksroot@ = pointer to keyset list head | |
7ed14135 | 548 | * @unsigned ty@ = expected type code |
410c8acf | 549 | * @buf *b@ = pointer to input buffer |
550 | * @buf *bb@ = pointer to output buffer | |
551 | * | |
a50f9a0e MW |
552 | * Returns: Zero on success; @KSERR_DECRYPT@ on failure. Also returns |
553 | * zero if there was insufficient buffer (but the output buffer | |
554 | * is broken in this case). | |
410c8acf | 555 | * |
556 | * Use: Decrypts a packet. | |
557 | */ | |
558 | ||
7ed14135 | 559 | int ksl_decrypt(keyset **ksroot, unsigned ty, buf *b, buf *bb) |
410c8acf | 560 | { |
561 | time_t now = time(0); | |
410c8acf | 562 | keyset *ks; |
426c0bc6 | 563 | uint32 seq; |
12a26b8b | 564 | int err; |
410c8acf | 565 | |
426c0bc6 | 566 | if (buf_ensure(bb, BLEN(b))) |
12a26b8b | 567 | return (0); |
09585a65 | 568 | |
410c8acf | 569 | for (ks = *ksroot; ks; ks = ks->next) { |
410c8acf | 570 | if (!KEYOK(ks, now)) |
571 | continue; | |
12a26b8b | 572 | if ((err = dodecrypt(ks, ty, b, bb, &seq)) == 0) { |
426c0bc6 | 573 | if (ks->f & KSF_LISTEN) { |
574 | T( trace(T_KEYSET, "keyset: implicitly activating keyset %u", | |
575 | ks->seq); ) | |
576 | ks->f &= ~KSF_LISTEN; | |
577 | } | |
a50f9a0e | 578 | if (seq_check(&ks->iseq, seq, "SYMM")) |
12a26b8b | 579 | return (KSERR_SEQ); |
a50f9a0e MW |
580 | else |
581 | return (0); | |
410c8acf | 582 | } |
12a26b8b | 583 | if (err != KSERR_DECRYPT) return (err); |
410c8acf | 584 | } |
e945d6e4 | 585 | T( trace(T_KEYSET, "keyset: no matching keys, or incorrect MAC"); ) |
a50f9a0e | 586 | return (KSERR_DECRYPT); |
410c8acf | 587 | } |
588 | ||
589 | /*----- That's all, folks -------------------------------------------------*/ |