Commit | Line | Data |
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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 | ||
31 | /*----- Tunable parameters ------------------------------------------------*/ | |
32 | ||
426c0bc6 | 33 | #define T_EXP MIN(60) /* Expiry time for a key */ |
34 | #define T_REGEN MIN(45) /* Regeneration time for a key */ | |
410c8acf | 35 | |
36 | /*----- Handy macros ------------------------------------------------------*/ | |
37 | ||
38 | #define KEYOK(ks, now) ((ks)->sz_exp > 0 && (ks)->t_exp > now) | |
39 | ||
b5c45da1 | 40 | #define SEQSZ 4 /* Size of sequence number packet */ |
41 | ||
426c0bc6 | 42 | /*----- Low-level packet encryption and decryption ------------------------*/ |
410c8acf | 43 | |
59d670e7 | 44 | /* --- Encrypted data format --- * |
45 | * | |
7ed14135 | 46 | * Let %$p_i$% be the %$i$%-th plaintext message, with type %$t$%. We first |
e04c2d50 | 47 | * compute |
59d670e7 | 48 | * |
49 | * %$c_i = \mathcal{E}\textrm{-CBC}_{K_{\text{E}}}(p_i)$% | |
50 | * | |
51 | * as the CBC-ciphertext of %$p_i$%, and then | |
52 | * | |
7ed14135 | 53 | * %$\sigma_i = \mathcal{T}_{K_{\text{M}}}(t, i, c_i)$% |
59d670e7 | 54 | * |
55 | * as a MAC on the %%\emph{ciphertext}%%. The message sent is then the pair | |
56 | * %$(\sigma_i, c_i)$%. This construction is provably secure in the NM-CCA | |
57 | * sense (assuming that the cipher is IND-CPA, and the MAC is SUF-CMA) | |
58 | * [Bellare and Namprempre]. | |
59 | * | |
60 | * This also ensures that, assuming the key is good, we have a secure channel | |
61 | * [Krawczyk]. Actually, [Krawczyk] shows that, if the cipher is either a | |
62 | * simple stream cipher or a block cipher in CBC mode, we can use the MAC- | |
63 | * then-encrypt scheme and still have a secure channel. However, I like the | |
64 | * NM-CCA guarantee from [Bellare and Namprempre]. I'm less worried about | |
65 | * the Horton Principle [Wagner and Schneier]. | |
66 | */ | |
67 | ||
426c0bc6 | 68 | /* --- @doencrypt@ --- * |
410c8acf | 69 | * |
426c0bc6 | 70 | * Arguments: @keyset *ks@ = pointer to keyset to use |
7ed14135 | 71 | * @unsigned ty@ = type of message this is |
426c0bc6 | 72 | * @buf *b@ = pointer to an input buffer |
73 | * @buf *bb@ = pointer to an output buffer | |
410c8acf | 74 | * |
a50f9a0e MW |
75 | * Returns: Zero if OK; @KSERR_REGEN@ if it's time to generate new keys. |
76 | * Also returns zero if there was insufficient buffer space, but | |
77 | * the buffer is broken in this case. | |
410c8acf | 78 | * |
426c0bc6 | 79 | * Use: Encrypts a message with the given key. We assume that the |
80 | * keyset is OK to use. | |
410c8acf | 81 | */ |
82 | ||
7ed14135 | 83 | static int doencrypt(keyset *ks, unsigned ty, buf *b, buf *bb) |
410c8acf | 84 | { |
426c0bc6 | 85 | ghash *h; |
b5c45da1 | 86 | gcipher *c = ks->cout; |
426c0bc6 | 87 | const octet *p = BCUR(b); |
88 | size_t sz = BLEFT(b); | |
59d670e7 | 89 | octet *qmac, *qseq, *qiv, *qpk; |
426c0bc6 | 90 | uint32 oseq; |
b5c45da1 | 91 | size_t ivsz = GC_CLASS(c)->blksz; |
92 | size_t tagsz = ks->tagsz; | |
426c0bc6 | 93 | size_t osz, nsz; |
7ed14135 | 94 | octet t[4]; |
426c0bc6 | 95 | int rc = 0; |
96 | ||
97 | /* --- Allocate the required buffer space --- */ | |
98 | ||
b5c45da1 | 99 | if (buf_ensure(bb, tagsz + SEQSZ + ivsz + sz)) |
426c0bc6 | 100 | return (0); /* Caution! */ |
b5c45da1 | 101 | qmac = BCUR(bb); qseq = qmac + tagsz; qiv = qseq + SEQSZ; qpk = qiv + ivsz; |
102 | BSTEP(bb, tagsz + SEQSZ + ivsz + sz); | |
7ed14135 | 103 | STORE32(t, ty); |
426c0bc6 | 104 | |
426c0bc6 | 105 | oseq = ks->oseq++; STORE32(qseq, oseq); |
426c0bc6 | 106 | IF_TRACING(T_KEYSET, { |
107 | trace(T_KEYSET, "keyset: encrypting packet %lu using keyset %u", | |
108 | (unsigned long)oseq, ks->seq); | |
b5c45da1 | 109 | trace_block(T_CRYPTO, "crypto: plaintext packet", p, sz); |
426c0bc6 | 110 | }) |
59d670e7 | 111 | |
b5c45da1 | 112 | /* --- Encrypt the packet --- */ |
59d670e7 | 113 | |
b5c45da1 | 114 | if (ivsz) { |
115 | rand_get(RAND_GLOBAL, qiv, ivsz); | |
116 | GC_SETIV(c, qiv); | |
117 | IF_TRACING(T_KEYSET, { | |
118 | trace_block(T_CRYPTO, "crypto: initialization vector", qiv, ivsz); | |
119 | }) | |
120 | } | |
121 | GC_ENCRYPT(c, p, qpk, sz); | |
426c0bc6 | 122 | IF_TRACING(T_KEYSET, { |
b5c45da1 | 123 | trace_block(T_CRYPTO, "crypto: encrypted packet", qpk, sz); |
426c0bc6 | 124 | }) |
125 | ||
b5c45da1 | 126 | /* --- Now compute the MAC --- */ |
127 | ||
128 | if (tagsz) { | |
129 | h = GM_INIT(ks->mout); | |
130 | GH_HASH(h, t, sizeof(t)); | |
131 | GH_HASH(h, qseq, SEQSZ + ivsz + sz); | |
132 | memcpy(qmac, GH_DONE(h, 0), tagsz); | |
133 | GH_DESTROY(h); | |
134 | IF_TRACING(T_KEYSET, { | |
135 | trace_block(T_CRYPTO, "crypto: computed MAC", qmac, tagsz); | |
136 | }) | |
137 | } | |
138 | ||
426c0bc6 | 139 | /* --- Deduct the packet size from the key's data life --- */ |
140 | ||
141 | osz = ks->sz_exp; | |
142 | if (osz > sz) | |
143 | nsz = osz - sz; | |
144 | else | |
145 | nsz = 0; | |
383a9d71 | 146 | if (osz >= ks->sz_regen && ks->sz_regen > nsz) { |
426c0bc6 | 147 | T( trace(T_KEYSET, "keyset: keyset %u data regen limit exceeded -- " |
148 | "forcing exchange", ks->seq); ) | |
a50f9a0e | 149 | rc = KSERR_REGEN; |
426c0bc6 | 150 | } |
151 | ks->sz_exp = nsz; | |
e04c2d50 | 152 | return (rc); |
410c8acf | 153 | } |
154 | ||
426c0bc6 | 155 | /* --- @dodecrypt@ --- * |
410c8acf | 156 | * |
426c0bc6 | 157 | * Arguments: @keyset *ks@ = pointer to keyset to use |
7ed14135 | 158 | * @unsigned ty@ = expected type code |
426c0bc6 | 159 | * @buf *b@ = pointer to an input buffer |
160 | * @buf *bb@ = pointer to an output buffer | |
161 | * @uint32 *seq@ = where to store the sequence number | |
410c8acf | 162 | * |
a50f9a0e | 163 | * Returns: Zero on success; @KSERR_DECRYPT@ on failure. |
410c8acf | 164 | * |
426c0bc6 | 165 | * Use: Attempts to decrypt a message with the given key. No other |
166 | * checking (e.g., sequence number checks) is performed. We | |
167 | * assume that the keyset is OK to use, and that there is | |
168 | * sufficient output buffer space reserved. If the decryption | |
169 | * is successful, the buffer pointer is moved past the decrypted | |
170 | * packet, and the packet's sequence number is stored in @*seq@. | |
410c8acf | 171 | */ |
172 | ||
7ed14135 | 173 | static int dodecrypt(keyset *ks, unsigned ty, buf *b, buf *bb, uint32 *seq) |
410c8acf | 174 | { |
59d670e7 | 175 | const octet *pmac, *piv, *pseq, *ppk; |
426c0bc6 | 176 | size_t psz = BLEFT(b); |
177 | size_t sz; | |
178 | octet *q = BCUR(bb); | |
179 | ghash *h; | |
180 | gcipher *c = ks->cin; | |
b5c45da1 | 181 | size_t ivsz = GC_CLASS(c)->blksz; |
182 | size_t tagsz = ks->tagsz; | |
426c0bc6 | 183 | octet *mac; |
184 | int eq; | |
7ed14135 | 185 | octet t[4]; |
426c0bc6 | 186 | |
187 | /* --- Break up the packet into its components --- */ | |
188 | ||
b5c45da1 | 189 | if (psz < ivsz + SEQSZ + tagsz) { |
426c0bc6 | 190 | T( trace(T_KEYSET, "keyset: block too small for keyset %u", ks->seq); ) |
12a26b8b | 191 | return (KSERR_MALFORMED); |
410c8acf | 192 | } |
b5c45da1 | 193 | sz = psz - ivsz - SEQSZ - tagsz; |
194 | pmac = BCUR(b); pseq = pmac + tagsz; piv = pseq + SEQSZ; ppk = piv + ivsz; | |
7ed14135 | 195 | STORE32(t, ty); |
426c0bc6 | 196 | |
426c0bc6 | 197 | IF_TRACING(T_KEYSET, { |
198 | trace(T_KEYSET, "keyset: decrypting using keyset %u", ks->seq); | |
b5c45da1 | 199 | trace_block(T_CRYPTO, "crypto: ciphertext packet", ppk, sz); |
426c0bc6 | 200 | }) |
b5c45da1 | 201 | |
202 | /* --- Verify the MAC on the packet --- */ | |
203 | ||
204 | if (tagsz) { | |
205 | h = GM_INIT(ks->min); | |
206 | GH_HASH(h, t, sizeof(t)); | |
207 | GH_HASH(h, pseq, SEQSZ + ivsz + sz); | |
208 | mac = GH_DONE(h, 0); | |
209 | eq = !memcmp(mac, pmac, tagsz); | |
426c0bc6 | 210 | IF_TRACING(T_KEYSET, { |
b5c45da1 | 211 | trace_block(T_CRYPTO, "crypto: computed MAC", mac, tagsz); |
426c0bc6 | 212 | }) |
b5c45da1 | 213 | GH_DESTROY(h); |
214 | if (!eq) { | |
215 | IF_TRACING(T_KEYSET, { | |
216 | trace(T_KEYSET, "keyset: incorrect MAC: decryption failed"); | |
217 | trace_block(T_CRYPTO, "crypto: expected MAC", pmac, tagsz); | |
218 | }) | |
a50f9a0e | 219 | return (KSERR_DECRYPT); |
b5c45da1 | 220 | } |
426c0bc6 | 221 | } |
59d670e7 | 222 | |
223 | /* --- Decrypt the packet --- */ | |
224 | ||
b5c45da1 | 225 | if (ivsz) { |
226 | GC_SETIV(c, piv); | |
227 | IF_TRACING(T_KEYSET, { | |
228 | trace_block(T_CRYPTO, "crypto: initialization vector", piv, ivsz); | |
229 | }) | |
230 | } | |
231 | GC_DECRYPT(c, ppk, q, sz); | |
426c0bc6 | 232 | if (seq) |
233 | *seq = LOAD32(pseq); | |
234 | IF_TRACING(T_KEYSET, { | |
235 | trace(T_KEYSET, "keyset: decrypted OK (sequence = %lu)", | |
236 | (unsigned long)LOAD32(pseq)); | |
237 | trace_block(T_CRYPTO, "crypto: decrypted packet", q, sz); | |
238 | }) | |
239 | BSTEP(bb, sz); | |
240 | return (0); | |
410c8acf | 241 | } |
242 | ||
426c0bc6 | 243 | /*----- Operations on a single keyset -------------------------------------*/ |
244 | ||
245 | /* --- @ks_drop@ --- * | |
246 | * | |
247 | * Arguments: @keyset *ks@ = pointer to a keyset | |
248 | * | |
249 | * Returns: --- | |
250 | * | |
251 | * Use: Decrements a keyset's reference counter. If the counter hits | |
252 | * zero, the keyset is freed. | |
253 | */ | |
254 | ||
255 | void ks_drop(keyset *ks) | |
256 | { | |
257 | if (--ks->ref) | |
258 | return; | |
b5c45da1 | 259 | GC_DESTROY(ks->cin); |
260 | GC_DESTROY(ks->cout); | |
261 | GM_DESTROY(ks->min); | |
262 | GM_DESTROY(ks->mout); | |
426c0bc6 | 263 | DESTROY(ks); |
410c8acf | 264 | } |
265 | ||
266 | /* --- @ks_gen@ --- * | |
267 | * | |
426c0bc6 | 268 | * Arguments: @const void *k@ = pointer to key material |
269 | * @size_t x, y, z@ = offsets into key material (see below) | |
e04c2d50 | 270 | * @peer *p@ = pointer to peer information |
410c8acf | 271 | * |
426c0bc6 | 272 | * Returns: A pointer to the new keyset. |
410c8acf | 273 | * |
426c0bc6 | 274 | * Use: Derives a new keyset from the given key material. The |
275 | * offsets @x@, @y@ and @z@ separate the key material into three | |
276 | * parts. Between the @k@ and @k + x@ is `my' contribution to | |
277 | * the key material; between @k + x@ and @k + y@ is `your' | |
278 | * contribution; and between @k + y@ and @k + z@ is a shared | |
279 | * value we made together. These are used to construct two | |
280 | * pairs of symmetric keys. Each pair consists of an encryption | |
281 | * key and a message authentication key. One pair is used for | |
282 | * outgoing messages, the other for incoming messages. | |
283 | * | |
284 | * The new key is marked so that it won't be selected for output | |
285 | * by @ksl_encrypt@. You can still encrypt data with it by | |
286 | * calling @ks_encrypt@ directly. | |
410c8acf | 287 | */ |
288 | ||
9466fafa | 289 | keyset *ks_gen(const void *k, size_t x, size_t y, size_t z, peer *p) |
410c8acf | 290 | { |
b5c45da1 | 291 | ghash *h; |
292 | const octet *hh; | |
410c8acf | 293 | keyset *ks = CREATE(keyset); |
294 | time_t now = time(0); | |
9466fafa | 295 | const octet *pp = k; |
410c8acf | 296 | T( static unsigned seq = 0; ) |
297 | ||
298 | T( trace(T_KEYSET, "keyset: adding new keyset %u", seq); ) | |
299 | ||
426c0bc6 | 300 | /* --- Construct the various keys --- * |
301 | * | |
302 | * This is done with macros, because it's quite tedious. | |
303 | */ | |
304 | ||
b5c45da1 | 305 | #define MINE GH_HASH(h, pp, x) |
306 | #define YOURS GH_HASH(h, pp + x, y - x) | |
307 | #define OURS GH_HASH(h, pp + y, z - y) | |
308 | ||
309 | #define HASH_in MINE; YOURS; OURS | |
310 | #define HASH_out YOURS; MINE; OURS | |
311 | #define INIT_c(k) GC_INIT(algs.c, (k), algs.cksz) | |
312 | #define INIT_m(k) GM_KEY(algs.m, (k), algs.mksz) | |
313 | #define STR_c "encryption" | |
314 | #define STR_m "integrity" | |
315 | #define STR_in "incoming" | |
316 | #define STR_out "outgoing" | |
317 | ||
318 | #define SETKEY(a, dir) do { \ | |
319 | h = GH_INIT(algs.h); \ | |
320 | HASH_STRING(h, "tripe-" STR_##a); \ | |
321 | HASH_##dir; \ | |
322 | hh = GH_DONE(h, 0); \ | |
410c8acf | 323 | IF_TRACING(T_KEYSET, { \ |
b5c45da1 | 324 | trace_block(T_CRYPTO, "crypto: " STR_##dir " key " STR_##a, \ |
325 | hh, algs.a##ksz); \ | |
410c8acf | 326 | }) \ |
b5c45da1 | 327 | ks->a##dir = INIT_##a(hh); \ |
328 | GH_DESTROY(h); \ | |
410c8acf | 329 | } while (0) |
330 | ||
b5c45da1 | 331 | SETKEY(c, in); SETKEY(c, out); |
332 | SETKEY(m, in); SETKEY(m, out); | |
426c0bc6 | 333 | |
334 | #undef MINE | |
335 | #undef YOURS | |
336 | #undef OURS | |
b5c45da1 | 337 | #undef STR_c |
338 | #undef STR_m | |
339 | #undef STR_in | |
340 | #undef STR_out | |
341 | #undef INIT_c | |
342 | #undef INIT_m | |
343 | #undef HASH_in | |
344 | #undef HASH_out | |
345 | #undef SETKEY | |
410c8acf | 346 | |
347 | T( ks->seq = seq++; ) | |
e945d6e4 | 348 | ks->ref = 1; |
426c0bc6 | 349 | ks->t_exp = now + T_EXP; |
383a9d71 MW |
350 | ks->sz_exp = algs.expsz; |
351 | ks->sz_regen = algs.expsz/2; | |
37941236 | 352 | ks->oseq = 0; |
353 | seq_reset(&ks->iseq); | |
426c0bc6 | 354 | ks->next = 0; |
9466fafa | 355 | ks->p = p; |
426c0bc6 | 356 | ks->f = KSF_LISTEN; |
b5c45da1 | 357 | ks->tagsz = algs.tagsz; |
426c0bc6 | 358 | return (ks); |
359 | } | |
360 | ||
361 | /* --- @ks_tregen@ --- * | |
362 | * | |
363 | * Arguments: @keyset *ks@ = pointer to a keyset | |
364 | * | |
365 | * Returns: The time at which moves ought to be made to replace this key. | |
366 | */ | |
367 | ||
368 | time_t ks_tregen(keyset *ks) { return (ks->t_exp - T_EXP + T_REGEN); } | |
369 | ||
370 | /* --- @ks_activate@ --- * | |
371 | * | |
372 | * Arguments: @keyset *ks@ = pointer to a keyset | |
373 | * | |
374 | * Returns: --- | |
375 | * | |
376 | * Use: Activates a keyset, so that it can be used for encrypting | |
377 | * outgoing messages. | |
378 | */ | |
379 | ||
380 | void ks_activate(keyset *ks) | |
381 | { | |
382 | if (ks->f & KSF_LISTEN) { | |
383 | T( trace(T_KEYSET, "keyset: activating keyset %u", ks->seq); ) | |
384 | ks->f &= ~KSF_LISTEN; | |
385 | } | |
410c8acf | 386 | } |
387 | ||
388 | /* --- @ks_encrypt@ --- * | |
389 | * | |
426c0bc6 | 390 | * Arguments: @keyset *ks@ = pointer to a keyset |
7ed14135 | 391 | * @unsigned ty@ = message type |
426c0bc6 | 392 | * @buf *b@ = pointer to input buffer |
393 | * @buf *bb@ = pointer to output buffer | |
394 | * | |
a50f9a0e MW |
395 | * Returns: Zero if successful; @KSERR_REGEN@ if we should negotiate a |
396 | * new key; @KSERR_NOKEYS@ if the key is not usable. Also | |
397 | * returns zero if there was insufficient buffer (but the output | |
398 | * buffer is broken in this case). | |
426c0bc6 | 399 | * |
400 | * Use: Encrypts a block of data using the key. Note that the `key | |
401 | * ought to be replaced' notification is only ever given once | |
402 | * for each key. Also note that this call forces a keyset to be | |
403 | * used even if it's marked as not for data output. | |
404 | */ | |
405 | ||
7ed14135 | 406 | int ks_encrypt(keyset *ks, unsigned ty, buf *b, buf *bb) |
426c0bc6 | 407 | { |
408 | time_t now = time(0); | |
409 | ||
410 | if (!KEYOK(ks, now)) { | |
411 | buf_break(bb); | |
a50f9a0e | 412 | return (KSERR_NOKEYS); |
426c0bc6 | 413 | } |
7ed14135 | 414 | return (doencrypt(ks, ty, b, bb)); |
426c0bc6 | 415 | } |
416 | ||
417 | /* --- @ks_decrypt@ --- * | |
418 | * | |
419 | * Arguments: @keyset *ks@ = pointer to a keyset | |
7ed14135 | 420 | * @unsigned ty@ = expected type code |
426c0bc6 | 421 | * @buf *b@ = pointer to an input buffer |
422 | * @buf *bb@ = pointer to an output buffer | |
423 | * | |
12a26b8b | 424 | * Returns: Zero on success; @KSERR_...@ on failure. Also returns |
a50f9a0e MW |
425 | * zero if there was insufficient buffer (but the output buffer |
426 | * is broken in this case). | |
426c0bc6 | 427 | * |
428 | * Use: Attempts to decrypt a message using a given key. Note that | |
429 | * requesting decryption with a key directly won't clear a | |
430 | * marking that it's not for encryption. | |
431 | */ | |
432 | ||
7ed14135 | 433 | int ks_decrypt(keyset *ks, unsigned ty, buf *b, buf *bb) |
426c0bc6 | 434 | { |
435 | time_t now = time(0); | |
436 | uint32 seq; | |
12a26b8b | 437 | int err; |
426c0bc6 | 438 | |
12a26b8b MW |
439 | if (!KEYOK(ks, now)) return (KSERR_DECRYPT); |
440 | if (buf_ensure(bb, BLEN(b))) return (0); | |
441 | if ((err = dodecrypt(ks, ty, b, bb, &seq)) != 0) return (err); | |
442 | if (seq_check(&ks->iseq, seq, "SYMM")) return (KSERR_SEQ); | |
426c0bc6 | 443 | return (0); |
444 | } | |
445 | ||
446 | /*----- Keyset list handling ----------------------------------------------*/ | |
447 | ||
448 | /* --- @ksl_free@ --- * | |
449 | * | |
450 | * Arguments: @keyset **ksroot@ = pointer to keyset list head | |
451 | * | |
452 | * Returns: --- | |
453 | * | |
454 | * Use: Frees (releases references to) all of the keys in a keyset. | |
455 | */ | |
456 | ||
457 | void ksl_free(keyset **ksroot) | |
458 | { | |
459 | keyset *ks, *ksn; | |
460 | for (ks = *ksroot; ks; ks = ksn) { | |
461 | ksn = ks->next; | |
462 | ks->f &= ~KSF_LINK; | |
463 | ks_drop(ks); | |
464 | } | |
465 | } | |
466 | ||
467 | /* --- @ksl_link@ --- * | |
468 | * | |
469 | * Arguments: @keyset **ksroot@ = pointer to keyset list head | |
470 | * @keyset *ks@ = pointer to a keyset | |
471 | * | |
472 | * Returns: --- | |
473 | * | |
474 | * Use: Links a keyset into a list. A keyset can only be on one list | |
475 | * at a time. Bad things happen otherwise. | |
476 | */ | |
477 | ||
478 | void ksl_link(keyset **ksroot, keyset *ks) | |
479 | { | |
480 | assert(!(ks->f & KSF_LINK)); | |
481 | ks->next = *ksroot; | |
482 | *ksroot = ks; | |
483 | ks->f |= KSF_LINK; | |
484 | ks->ref++; | |
485 | } | |
486 | ||
487 | /* --- @ksl_prune@ --- * | |
488 | * | |
489 | * Arguments: @keyset **ksroot@ = pointer to keyset list head | |
490 | * | |
491 | * Returns: --- | |
492 | * | |
493 | * Use: Prunes the keyset list by removing keys which mustn't be used | |
494 | * any more. | |
495 | */ | |
496 | ||
497 | void ksl_prune(keyset **ksroot) | |
498 | { | |
499 | time_t now = time(0); | |
500 | ||
501 | while (*ksroot) { | |
502 | keyset *ks = *ksroot; | |
503 | ||
504 | if (ks->t_exp <= now) { | |
505 | T( trace(T_KEYSET, "keyset: expiring keyset %u (time limit reached)", | |
506 | ks->seq); ) | |
507 | goto kill; | |
508 | } else if (ks->sz_exp == 0) { | |
509 | T( trace(T_KEYSET, "keyset: expiring keyset %u (data limit reached)", | |
510 | ks->seq); ) | |
511 | goto kill; | |
512 | } else { | |
513 | ksroot = &ks->next; | |
514 | continue; | |
515 | } | |
516 | ||
517 | kill: | |
518 | *ksroot = ks->next; | |
519 | ks->f &= ~KSF_LINK; | |
520 | ks_drop(ks); | |
521 | } | |
522 | } | |
523 | ||
524 | /* --- @ksl_encrypt@ --- * | |
525 | * | |
410c8acf | 526 | * Arguments: @keyset **ksroot@ = pointer to keyset list head |
7ed14135 | 527 | * @unsigned ty@ = message type |
410c8acf | 528 | * @buf *b@ = pointer to input buffer |
529 | * @buf *bb@ = pointer to output buffer | |
530 | * | |
a50f9a0e MW |
531 | * Returns: Zero if successful; @KSERR_REGEN@ if it's time to negotiate a |
532 | * new key; @KSERR_NOKEYS@ if there are no suitable keys | |
533 | * available. Also returns zero if there was insufficient | |
534 | * buffer space (but the output buffer is broken in this case). | |
410c8acf | 535 | * |
536 | * Use: Encrypts a packet. | |
537 | */ | |
538 | ||
7ed14135 | 539 | int ksl_encrypt(keyset **ksroot, unsigned ty, buf *b, buf *bb) |
410c8acf | 540 | { |
541 | time_t now = time(0); | |
426c0bc6 | 542 | keyset *ks = *ksroot; |
410c8acf | 543 | |
410c8acf | 544 | for (;;) { |
545 | if (!ks) { | |
426c0bc6 | 546 | T( trace(T_KEYSET, "keyset: no suitable keysets found"); ) |
410c8acf | 547 | buf_break(bb); |
a50f9a0e | 548 | return (KSERR_NOKEYS); |
410c8acf | 549 | } |
426c0bc6 | 550 | if (KEYOK(ks, now) && !(ks->f & KSF_LISTEN)) |
410c8acf | 551 | break; |
552 | ks = ks->next; | |
553 | } | |
554 | ||
7ed14135 | 555 | return (doencrypt(ks, ty, b, bb)); |
410c8acf | 556 | } |
557 | ||
426c0bc6 | 558 | /* --- @ksl_decrypt@ --- * |
410c8acf | 559 | * |
560 | * Arguments: @keyset **ksroot@ = pointer to keyset list head | |
7ed14135 | 561 | * @unsigned ty@ = expected type code |
410c8acf | 562 | * @buf *b@ = pointer to input buffer |
563 | * @buf *bb@ = pointer to output buffer | |
564 | * | |
a50f9a0e MW |
565 | * Returns: Zero on success; @KSERR_DECRYPT@ on failure. Also returns |
566 | * zero if there was insufficient buffer (but the output buffer | |
567 | * is broken in this case). | |
410c8acf | 568 | * |
569 | * Use: Decrypts a packet. | |
570 | */ | |
571 | ||
7ed14135 | 572 | int ksl_decrypt(keyset **ksroot, unsigned ty, buf *b, buf *bb) |
410c8acf | 573 | { |
574 | time_t now = time(0); | |
410c8acf | 575 | keyset *ks; |
426c0bc6 | 576 | uint32 seq; |
12a26b8b | 577 | int err; |
410c8acf | 578 | |
426c0bc6 | 579 | if (buf_ensure(bb, BLEN(b))) |
12a26b8b | 580 | return (0); |
09585a65 | 581 | |
410c8acf | 582 | for (ks = *ksroot; ks; ks = ks->next) { |
410c8acf | 583 | if (!KEYOK(ks, now)) |
584 | continue; | |
12a26b8b | 585 | if ((err = dodecrypt(ks, ty, b, bb, &seq)) == 0) { |
426c0bc6 | 586 | if (ks->f & KSF_LISTEN) { |
587 | T( trace(T_KEYSET, "keyset: implicitly activating keyset %u", | |
588 | ks->seq); ) | |
589 | ks->f &= ~KSF_LISTEN; | |
590 | } | |
a50f9a0e | 591 | if (seq_check(&ks->iseq, seq, "SYMM")) |
12a26b8b | 592 | return (KSERR_SEQ); |
a50f9a0e MW |
593 | else |
594 | return (0); | |
410c8acf | 595 | } |
12a26b8b | 596 | if (err != KSERR_DECRYPT) return (err); |
410c8acf | 597 | } |
e945d6e4 | 598 | T( trace(T_KEYSET, "keyset: no matching keys, or incorrect MAC"); ) |
a50f9a0e | 599 | return (KSERR_DECRYPT); |
410c8acf | 600 | } |
601 | ||
602 | /*----- That's all, folks -------------------------------------------------*/ |