torcert.c 23 KB

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  1. /* Copyright (c) 2014-2017, The Tor Project, Inc. */
  2. /* See LICENSE for licensing information */
  3. /**
  4. * \file torcert.c
  5. *
  6. * \brief Implementation for ed25519-signed certificates as used in the Tor
  7. * protocol.
  8. *
  9. * This certificate format is designed to be simple and compact; it's
  10. * documented in tor-spec.txt in the torspec.git repository. All of the
  11. * certificates in this format are signed with an Ed25519 key; the
  12. * contents themselves may be another Ed25519 key, a digest of a
  13. * RSA key, or some other material.
  14. *
  15. * In this module there is also support for a crooss-certification of
  16. * Ed25519 identities using (older) RSA1024 identities.
  17. *
  18. * Tor uses other types of certificate too, beyond those described in this
  19. * module. Notably, our use of TLS requires us to touch X.509 certificates,
  20. * even though sensible people would stay away from those. Our X.509
  21. * certificates are represented with tor_x509_cert_t, and implemented in
  22. * tortls.c. We also have a separate certificate type that authorities
  23. * use to authenticate their RSA signing keys with their RSA identity keys:
  24. * that one is authority_cert_t, and it's mostly handled in routerlist.c.
  25. */
  26. #include "or.h"
  27. #include "config.h"
  28. #include "crypto.h"
  29. #include "torcert.h"
  30. #include "ed25519_cert.h"
  31. #include "torlog.h"
  32. #include "util.h"
  33. #include "compat.h"
  34. #include "link_handshake.h"
  35. /** Helper for tor_cert_create(): signs any 32 bytes, not just an ed25519
  36. * key.
  37. */
  38. static tor_cert_t *
  39. tor_cert_sign_impl(const ed25519_keypair_t *signing_key,
  40. uint8_t cert_type,
  41. uint8_t signed_key_type,
  42. const uint8_t signed_key_info[32],
  43. time_t now, time_t lifetime,
  44. uint32_t flags)
  45. {
  46. tor_cert_t *torcert = NULL;
  47. ed25519_cert_t *cert = ed25519_cert_new();
  48. cert->cert_type = cert_type;
  49. cert->exp_field = (uint32_t) CEIL_DIV(now + lifetime, 3600);
  50. cert->cert_key_type = signed_key_type;
  51. memcpy(cert->certified_key, signed_key_info, 32);
  52. if (flags & CERT_FLAG_INCLUDE_SIGNING_KEY) {
  53. ed25519_cert_extension_t *ext = ed25519_cert_extension_new();
  54. ext->ext_type = CERTEXT_SIGNED_WITH_KEY;
  55. memcpy(ext->un_signing_key, signing_key->pubkey.pubkey, 32);
  56. ed25519_cert_add_ext(cert, ext);
  57. ++cert->n_extensions;
  58. }
  59. const ssize_t alloc_len = ed25519_cert_encoded_len(cert);
  60. tor_assert(alloc_len > 0);
  61. uint8_t *encoded = tor_malloc(alloc_len);
  62. const ssize_t real_len = ed25519_cert_encode(encoded, alloc_len, cert);
  63. if (real_len < 0)
  64. goto err;
  65. tor_assert(real_len == alloc_len);
  66. tor_assert(real_len > ED25519_SIG_LEN);
  67. uint8_t *sig = encoded + (real_len - ED25519_SIG_LEN);
  68. tor_assert(tor_mem_is_zero((char*)sig, ED25519_SIG_LEN));
  69. ed25519_signature_t signature;
  70. if (ed25519_sign(&signature, encoded,
  71. real_len-ED25519_SIG_LEN, signing_key)<0) {
  72. log_warn(LD_BUG, "Can't sign certificate");
  73. goto err;
  74. }
  75. memcpy(sig, signature.sig, ED25519_SIG_LEN);
  76. torcert = tor_cert_parse(encoded, real_len);
  77. if (! torcert) {
  78. log_warn(LD_BUG, "Generated a certificate we cannot parse");
  79. goto err;
  80. }
  81. if (tor_cert_checksig(torcert, &signing_key->pubkey, now) < 0) {
  82. log_warn(LD_BUG, "Generated a certificate whose signature we can't check");
  83. goto err;
  84. }
  85. tor_free(encoded);
  86. goto done;
  87. err:
  88. tor_cert_free(torcert);
  89. torcert = NULL;
  90. done:
  91. ed25519_cert_free(cert);
  92. tor_free(encoded);
  93. return torcert;
  94. }
  95. /**
  96. * Create and return a new new certificate of type <b>cert_type</b> to
  97. * authenticate <b>signed_key</b> using the key <b>signing_key</b>. The
  98. * certificate should remain valid for at least <b>lifetime</b> seconds after
  99. * <b>now</b>.
  100. *
  101. * If CERT_FLAG_INCLUDE_SIGNING_KEY is set in <b>flags</b>, embed
  102. * the public part of <b>signing_key</b> in the certificate.
  103. */
  104. tor_cert_t *
  105. tor_cert_create(const ed25519_keypair_t *signing_key,
  106. uint8_t cert_type,
  107. const ed25519_public_key_t *signed_key,
  108. time_t now, time_t lifetime,
  109. uint32_t flags)
  110. {
  111. return tor_cert_sign_impl(signing_key, cert_type,
  112. SIGNED_KEY_TYPE_ED25519, signed_key->pubkey,
  113. now, lifetime, flags);
  114. }
  115. /** Release all storage held for <b>cert</b>. */
  116. void
  117. tor_cert_free(tor_cert_t *cert)
  118. {
  119. if (! cert)
  120. return;
  121. if (cert->encoded)
  122. memwipe(cert->encoded, 0, cert->encoded_len);
  123. tor_free(cert->encoded);
  124. memwipe(cert, 0, sizeof(tor_cert_t));
  125. tor_free(cert);
  126. }
  127. /** Parse a certificate encoded with <b>len</b> bytes in <b>encoded</b>. */
  128. tor_cert_t *
  129. tor_cert_parse(const uint8_t *encoded, const size_t len)
  130. {
  131. tor_cert_t *cert = NULL;
  132. ed25519_cert_t *parsed = NULL;
  133. ssize_t got_len = ed25519_cert_parse(&parsed, encoded, len);
  134. if (got_len < 0 || (size_t) got_len != len)
  135. goto err;
  136. cert = tor_malloc_zero(sizeof(tor_cert_t));
  137. cert->encoded = tor_memdup(encoded, len);
  138. cert->encoded_len = len;
  139. memcpy(cert->signed_key.pubkey, parsed->certified_key, 32);
  140. int64_t valid_until_64 = ((int64_t)parsed->exp_field) * 3600;
  141. #if SIZEOF_TIME_T < SIZEOF_INT64_T
  142. if (valid_until_64 > TIME_MAX)
  143. valid_until_64 = TIME_MAX - 1;
  144. #endif
  145. cert->valid_until = (time_t) valid_until_64;
  146. cert->cert_type = parsed->cert_type;
  147. for (unsigned i = 0; i < ed25519_cert_getlen_ext(parsed); ++i) {
  148. ed25519_cert_extension_t *ext = ed25519_cert_get_ext(parsed, i);
  149. if (ext->ext_type == CERTEXT_SIGNED_WITH_KEY) {
  150. if (cert->signing_key_included)
  151. goto err;
  152. cert->signing_key_included = 1;
  153. memcpy(cert->signing_key.pubkey, ext->un_signing_key, 32);
  154. } else if (ext->ext_flags & CERTEXT_FLAG_AFFECTS_VALIDATION) {
  155. /* Unrecognized extension with affects_validation set */
  156. goto err;
  157. }
  158. }
  159. goto done;
  160. err:
  161. tor_cert_free(cert);
  162. cert = NULL;
  163. done:
  164. ed25519_cert_free(parsed);
  165. return cert;
  166. }
  167. /** Fill in <b>checkable_out</b> with the information needed to check
  168. * the signature on <b>cert</b> with <b>pubkey</b>.
  169. *
  170. * On success, if <b>expiration_out</b> is provided, and it is some time
  171. * _after_ the expiration time of this certificate, set it to the
  172. * expiration time of this certificate.
  173. */
  174. int
  175. tor_cert_get_checkable_sig(ed25519_checkable_t *checkable_out,
  176. const tor_cert_t *cert,
  177. const ed25519_public_key_t *pubkey,
  178. time_t *expiration_out)
  179. {
  180. if (! pubkey) {
  181. if (cert->signing_key_included)
  182. pubkey = &cert->signing_key;
  183. else
  184. return -1;
  185. }
  186. checkable_out->msg = cert->encoded;
  187. checkable_out->pubkey = pubkey;
  188. tor_assert(cert->encoded_len > ED25519_SIG_LEN);
  189. const size_t signed_len = cert->encoded_len - ED25519_SIG_LEN;
  190. checkable_out->len = signed_len;
  191. memcpy(checkable_out->signature.sig,
  192. cert->encoded + signed_len, ED25519_SIG_LEN);
  193. if (expiration_out) {
  194. *expiration_out = MIN(*expiration_out, cert->valid_until);
  195. }
  196. return 0;
  197. }
  198. /** Validates the signature on <b>cert</b> with <b>pubkey</b> relative to the
  199. * current time <b>now</b>. (If <b>now</b> is 0, do not check the expiration
  200. * time.) Return 0 on success, -1 on failure. Sets flags in <b>cert</b> as
  201. * appropriate.
  202. */
  203. int
  204. tor_cert_checksig(tor_cert_t *cert,
  205. const ed25519_public_key_t *pubkey, time_t now)
  206. {
  207. ed25519_checkable_t checkable;
  208. int okay;
  209. time_t expires = TIME_MAX;
  210. if (tor_cert_get_checkable_sig(&checkable, cert, pubkey, &expires) < 0)
  211. return -1;
  212. if (now && now > expires) {
  213. cert->cert_expired = 1;
  214. return -1;
  215. }
  216. if (ed25519_checksig_batch(&okay, &checkable, 1) < 0) {
  217. cert->sig_bad = 1;
  218. return -1;
  219. } else {
  220. cert->sig_ok = 1;
  221. /* Only copy the checkable public key when it is different from the signing
  222. * key of the certificate to avoid undefined behavior. */
  223. if (cert->signing_key.pubkey != checkable.pubkey->pubkey) {
  224. memcpy(cert->signing_key.pubkey, checkable.pubkey->pubkey, 32);
  225. }
  226. cert->cert_valid = 1;
  227. return 0;
  228. }
  229. }
  230. /** Return a new copy of <b>cert</b> */
  231. tor_cert_t *
  232. tor_cert_dup(const tor_cert_t *cert)
  233. {
  234. tor_cert_t *newcert = tor_memdup(cert, sizeof(tor_cert_t));
  235. if (cert->encoded)
  236. newcert->encoded = tor_memdup(cert->encoded, cert->encoded_len);
  237. return newcert;
  238. }
  239. /** Return true iff cert1 and cert2 are the same cert. */
  240. int
  241. tor_cert_eq(const tor_cert_t *cert1, const tor_cert_t *cert2)
  242. {
  243. tor_assert(cert1);
  244. tor_assert(cert2);
  245. return cert1->encoded_len == cert2->encoded_len &&
  246. tor_memeq(cert1->encoded, cert2->encoded, cert1->encoded_len);
  247. }
  248. /** Return true iff cert1 and cert2 are the same cert, or if they are both
  249. * NULL. */
  250. int
  251. tor_cert_opt_eq(const tor_cert_t *cert1, const tor_cert_t *cert2)
  252. {
  253. if (cert1 == NULL && cert2 == NULL)
  254. return 1;
  255. if (!cert1 || !cert2)
  256. return 0;
  257. return tor_cert_eq(cert1, cert2);
  258. }
  259. #define RSA_ED_CROSSCERT_PREFIX "Tor TLS RSA/Ed25519 cross-certificate"
  260. /** Create new cross-certification object to certify <b>ed_key</b> as the
  261. * master ed25519 identity key for the RSA identity key <b>rsa_key</b>.
  262. * Allocates and stores the encoded certificate in *<b>cert</b>, and returns
  263. * the number of bytes stored. Returns negative on error.*/
  264. ssize_t
  265. tor_make_rsa_ed25519_crosscert(const ed25519_public_key_t *ed_key,
  266. const crypto_pk_t *rsa_key,
  267. time_t expires,
  268. uint8_t **cert)
  269. {
  270. // It is later than 1985, since otherwise there would be no C89
  271. // compilers. (Try to diagnose #22466.)
  272. tor_assert_nonfatal(expires >= 15 * 365 * 86400);
  273. uint8_t *res;
  274. rsa_ed_crosscert_t *cc = rsa_ed_crosscert_new();
  275. memcpy(cc->ed_key, ed_key->pubkey, ED25519_PUBKEY_LEN);
  276. cc->expiration = (uint32_t) CEIL_DIV(expires, 3600);
  277. cc->sig_len = crypto_pk_keysize(rsa_key);
  278. rsa_ed_crosscert_setlen_sig(cc, crypto_pk_keysize(rsa_key));
  279. ssize_t alloc_sz = rsa_ed_crosscert_encoded_len(cc);
  280. tor_assert(alloc_sz > 0);
  281. res = tor_malloc_zero(alloc_sz);
  282. ssize_t sz = rsa_ed_crosscert_encode(res, alloc_sz, cc);
  283. tor_assert(sz > 0 && sz <= alloc_sz);
  284. crypto_digest_t *d = crypto_digest256_new(DIGEST_SHA256);
  285. crypto_digest_add_bytes(d, RSA_ED_CROSSCERT_PREFIX,
  286. strlen(RSA_ED_CROSSCERT_PREFIX));
  287. const int signed_part_len = 32 + 4;
  288. crypto_digest_add_bytes(d, (char*)res, signed_part_len);
  289. uint8_t digest[DIGEST256_LEN];
  290. crypto_digest_get_digest(d, (char*)digest, sizeof(digest));
  291. crypto_digest_free(d);
  292. int siglen = crypto_pk_private_sign(rsa_key,
  293. (char*)rsa_ed_crosscert_getarray_sig(cc),
  294. rsa_ed_crosscert_getlen_sig(cc),
  295. (char*)digest, sizeof(digest));
  296. tor_assert(siglen > 0 && siglen <= (int)crypto_pk_keysize(rsa_key));
  297. tor_assert(siglen <= UINT8_MAX);
  298. cc->sig_len = siglen;
  299. rsa_ed_crosscert_setlen_sig(cc, siglen);
  300. sz = rsa_ed_crosscert_encode(res, alloc_sz, cc);
  301. rsa_ed_crosscert_free(cc);
  302. *cert = res;
  303. return sz;
  304. }
  305. /**
  306. * Check whether the <b>crosscert_len</b> byte certificate in <b>crosscert</b>
  307. * is in fact a correct cross-certification of <b>master_key</b> using
  308. * the RSA key <b>rsa_id_key</b>.
  309. *
  310. * Also reject the certificate if it expired before
  311. * <b>reject_if_expired_before</b>.
  312. *
  313. * Return 0 on success, negative on failure.
  314. */
  315. int
  316. rsa_ed25519_crosscert_check(const uint8_t *crosscert,
  317. const size_t crosscert_len,
  318. const crypto_pk_t *rsa_id_key,
  319. const ed25519_public_key_t *master_key,
  320. const time_t reject_if_expired_before)
  321. {
  322. rsa_ed_crosscert_t *cc = NULL;
  323. int rv;
  324. #define ERR(code, s) \
  325. do { \
  326. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, \
  327. "Received a bad RSA->Ed25519 crosscert: %s", \
  328. (s)); \
  329. rv = (code); \
  330. goto err; \
  331. } while (0)
  332. if (BUG(crypto_pk_keysize(rsa_id_key) > PK_BYTES))
  333. return -1;
  334. if (BUG(!crosscert))
  335. return -1;
  336. ssize_t parsed_len = rsa_ed_crosscert_parse(&cc, crosscert, crosscert_len);
  337. if (parsed_len < 0 || crosscert_len != (size_t)parsed_len) {
  338. ERR(-2, "Unparseable or overlong crosscert");
  339. }
  340. if (tor_memneq(rsa_ed_crosscert_getarray_ed_key(cc),
  341. master_key->pubkey,
  342. ED25519_PUBKEY_LEN)) {
  343. ERR(-3, "Crosscert did not match Ed25519 key");
  344. }
  345. const uint32_t expiration_date = rsa_ed_crosscert_get_expiration(cc);
  346. const uint64_t expiration_time = ((uint64_t)expiration_date) * 3600;
  347. if (reject_if_expired_before < 0 ||
  348. expiration_time < (uint64_t)reject_if_expired_before) {
  349. ERR(-4, "Crosscert is expired");
  350. }
  351. const uint8_t *eos = rsa_ed_crosscert_get_end_of_signed(cc);
  352. const uint8_t *sig = rsa_ed_crosscert_getarray_sig(cc);
  353. const uint8_t siglen = rsa_ed_crosscert_get_sig_len(cc);
  354. tor_assert(eos >= crosscert);
  355. tor_assert((size_t)(eos - crosscert) <= crosscert_len);
  356. tor_assert(siglen == rsa_ed_crosscert_getlen_sig(cc));
  357. /* Compute the digest */
  358. uint8_t digest[DIGEST256_LEN];
  359. crypto_digest_t *d = crypto_digest256_new(DIGEST_SHA256);
  360. crypto_digest_add_bytes(d, RSA_ED_CROSSCERT_PREFIX,
  361. strlen(RSA_ED_CROSSCERT_PREFIX));
  362. crypto_digest_add_bytes(d, (char*)crosscert, eos-crosscert);
  363. crypto_digest_get_digest(d, (char*)digest, sizeof(digest));
  364. crypto_digest_free(d);
  365. /* Now check the signature */
  366. uint8_t signed_[PK_BYTES];
  367. int signed_len = crypto_pk_public_checksig(rsa_id_key,
  368. (char*)signed_, sizeof(signed_),
  369. (char*)sig, siglen);
  370. if (signed_len < DIGEST256_LEN) {
  371. ERR(-5, "Bad signature, or length of signed data not as expected");
  372. }
  373. if (tor_memneq(digest, signed_, DIGEST256_LEN)) {
  374. ERR(-6, "The signature was good, but it didn't match the data");
  375. }
  376. rv = 0;
  377. err:
  378. rsa_ed_crosscert_free(cc);
  379. return rv;
  380. }
  381. /** Construct and return a new empty or_handshake_certs object */
  382. or_handshake_certs_t *
  383. or_handshake_certs_new(void)
  384. {
  385. return tor_malloc_zero(sizeof(or_handshake_certs_t));
  386. }
  387. /** Release all storage held in <b>certs</b> */
  388. void
  389. or_handshake_certs_free(or_handshake_certs_t *certs)
  390. {
  391. if (!certs)
  392. return;
  393. tor_x509_cert_free(certs->auth_cert);
  394. tor_x509_cert_free(certs->link_cert);
  395. tor_x509_cert_free(certs->id_cert);
  396. tor_cert_free(certs->ed_id_sign);
  397. tor_cert_free(certs->ed_sign_link);
  398. tor_cert_free(certs->ed_sign_auth);
  399. tor_free(certs->ed_rsa_crosscert);
  400. memwipe(certs, 0xBD, sizeof(*certs));
  401. tor_free(certs);
  402. }
  403. #undef ERR
  404. #define ERR(s) \
  405. do { \
  406. log_fn(severity, LD_PROTOCOL, \
  407. "Received a bad CERTS cell: %s", \
  408. (s)); \
  409. return 0; \
  410. } while (0)
  411. int
  412. or_handshake_certs_rsa_ok(int severity,
  413. or_handshake_certs_t *certs,
  414. tor_tls_t *tls,
  415. time_t now)
  416. {
  417. tor_x509_cert_t *link_cert = certs->link_cert;
  418. tor_x509_cert_t *auth_cert = certs->auth_cert;
  419. tor_x509_cert_t *id_cert = certs->id_cert;
  420. if (certs->started_here) {
  421. if (! (id_cert && link_cert))
  422. ERR("The certs we wanted (ID, Link) were missing");
  423. if (! tor_tls_cert_matches_key(tls, link_cert))
  424. ERR("The link certificate didn't match the TLS public key");
  425. if (! tor_tls_cert_is_valid(severity, link_cert, id_cert, now, 0))
  426. ERR("The link certificate was not valid");
  427. if (! tor_tls_cert_is_valid(severity, id_cert, id_cert, now, 1))
  428. ERR("The ID certificate was not valid");
  429. } else {
  430. if (! (id_cert && auth_cert))
  431. ERR("The certs we wanted (ID, Auth) were missing");
  432. if (! tor_tls_cert_is_valid(LOG_PROTOCOL_WARN, auth_cert, id_cert, now, 1))
  433. ERR("The authentication certificate was not valid");
  434. if (! tor_tls_cert_is_valid(LOG_PROTOCOL_WARN, id_cert, id_cert, now, 1))
  435. ERR("The ID certificate was not valid");
  436. }
  437. return 1;
  438. }
  439. /** Check all the ed25519 certificates in <b>certs</b> against each other, and
  440. * against the peer certificate in <b>tls</b> if appropriate. On success,
  441. * return 0; on failure, return a negative value and warn at level
  442. * <b>severity</b> */
  443. int
  444. or_handshake_certs_ed25519_ok(int severity,
  445. or_handshake_certs_t *certs,
  446. tor_tls_t *tls,
  447. time_t now)
  448. {
  449. ed25519_checkable_t check[10];
  450. unsigned n_checkable = 0;
  451. time_t expiration = TIME_MAX;
  452. #define ADDCERT(cert, pk) \
  453. do { \
  454. tor_assert(n_checkable < ARRAY_LENGTH(check)); \
  455. if (tor_cert_get_checkable_sig(&check[n_checkable++], cert, pk, \
  456. &expiration) < 0) \
  457. ERR("Could not get checkable cert."); \
  458. } while (0)
  459. if (! certs->ed_id_sign || !certs->ed_id_sign->signing_key_included) {
  460. ERR("No Ed25519 signing key");
  461. }
  462. ADDCERT(certs->ed_id_sign, NULL);
  463. if (certs->started_here) {
  464. if (! certs->ed_sign_link)
  465. ERR("No Ed25519 link key");
  466. {
  467. /* check for a match with the TLS cert. */
  468. tor_x509_cert_t *peer_cert = tor_tls_get_peer_cert(tls);
  469. if (BUG(!peer_cert)) {
  470. /* This is a bug, because if we got to this point, we are a connection
  471. * that was initiated here, and we completed a TLS handshake. The
  472. * other side *must* have given us a certificate! */
  473. ERR("No x509 peer cert"); // LCOV_EXCL_LINE
  474. }
  475. const common_digests_t *peer_cert_digests =
  476. tor_x509_cert_get_cert_digests(peer_cert);
  477. int okay = tor_memeq(peer_cert_digests->d[DIGEST_SHA256],
  478. certs->ed_sign_link->signed_key.pubkey,
  479. DIGEST256_LEN);
  480. tor_x509_cert_free(peer_cert);
  481. if (!okay)
  482. ERR("Link certificate does not match TLS certificate");
  483. }
  484. ADDCERT(certs->ed_sign_link, &certs->ed_id_sign->signed_key);
  485. } else {
  486. if (! certs->ed_sign_auth)
  487. ERR("No Ed25519 link authentication key");
  488. ADDCERT(certs->ed_sign_auth, &certs->ed_id_sign->signed_key);
  489. }
  490. if (expiration < now) {
  491. ERR("At least one certificate expired.");
  492. }
  493. /* Okay, we've gotten ready to check all the Ed25519 certificates.
  494. * Now, we are going to check the RSA certificate's cross-certification
  495. * with the ED certificates.
  496. *
  497. * FFFF In the future, we might want to make this optional.
  498. */
  499. tor_x509_cert_t *rsa_id_cert = certs->id_cert;
  500. if (!rsa_id_cert) {
  501. ERR("Missing legacy RSA ID certificate");
  502. }
  503. if (! tor_tls_cert_is_valid(severity, rsa_id_cert, rsa_id_cert, now, 1)) {
  504. ERR("The legacy RSA ID certificate was not valid");
  505. }
  506. if (! certs->ed_rsa_crosscert) {
  507. ERR("Missing RSA->Ed25519 crosscert");
  508. }
  509. crypto_pk_t *rsa_id_key = tor_tls_cert_get_key(rsa_id_cert);
  510. if (!rsa_id_key) {
  511. ERR("RSA ID cert had no RSA key");
  512. }
  513. if (rsa_ed25519_crosscert_check(certs->ed_rsa_crosscert,
  514. certs->ed_rsa_crosscert_len,
  515. rsa_id_key,
  516. &certs->ed_id_sign->signing_key,
  517. now) < 0) {
  518. crypto_pk_free(rsa_id_key);
  519. ERR("Invalid RSA->Ed25519 crosscert");
  520. }
  521. crypto_pk_free(rsa_id_key);
  522. rsa_id_key = NULL;
  523. /* FFFF We could save a little time in the client case by queueing
  524. * this batch to check it later, along with the signature from the
  525. * AUTHENTICATE cell. That will change our data flow a bit, though,
  526. * so I say "postpone". */
  527. if (ed25519_checksig_batch(NULL, check, n_checkable) < 0) {
  528. ERR("At least one Ed25519 certificate was badly signed");
  529. }
  530. return 1;
  531. }
  532. /**
  533. * Check the Ed certificates and/or the RSA certificates, as appropriate. If
  534. * we obtained an Ed25519 identity, set *ed_id_out. If we obtained an RSA
  535. * identity, set *rs_id_out. Otherwise, set them both to NULL.
  536. */
  537. void
  538. or_handshake_certs_check_both(int severity,
  539. or_handshake_certs_t *certs,
  540. tor_tls_t *tls,
  541. time_t now,
  542. const ed25519_public_key_t **ed_id_out,
  543. const common_digests_t **rsa_id_out)
  544. {
  545. tor_assert(ed_id_out);
  546. tor_assert(rsa_id_out);
  547. *ed_id_out = NULL;
  548. *rsa_id_out = NULL;
  549. if (certs->ed_id_sign) {
  550. if (or_handshake_certs_ed25519_ok(severity, certs, tls, now)) {
  551. tor_assert(certs->ed_id_sign);
  552. tor_assert(certs->id_cert);
  553. *ed_id_out = &certs->ed_id_sign->signing_key;
  554. *rsa_id_out = tor_x509_cert_get_id_digests(certs->id_cert);
  555. /* If we reached this point, we did not look at any of the
  556. * subsidiary RSA certificates, so we'd better just remove them.
  557. */
  558. tor_x509_cert_free(certs->link_cert);
  559. tor_x509_cert_free(certs->auth_cert);
  560. certs->link_cert = certs->auth_cert = NULL;
  561. }
  562. /* We do _not_ fall through here. If you provided us Ed25519
  563. * certificates, we expect to verify them! */
  564. } else {
  565. /* No ed25519 keys given in the CERTS cell */
  566. if (or_handshake_certs_rsa_ok(severity, certs, tls, now)) {
  567. *rsa_id_out = tor_x509_cert_get_id_digests(certs->id_cert);
  568. }
  569. }
  570. }
  571. /* === ENCODING === */
  572. /* Encode the ed25519 certificate <b>cert</b> and put the newly allocated
  573. * string in <b>cert_str_out</b>. Return 0 on success else a negative value. */
  574. int
  575. tor_cert_encode_ed22519(const tor_cert_t *cert, char **cert_str_out)
  576. {
  577. int ret = -1;
  578. char *ed_cert_b64 = NULL;
  579. size_t ed_cert_b64_len;
  580. tor_assert(cert);
  581. tor_assert(cert_str_out);
  582. /* Get the encoded size and add the NUL byte. */
  583. ed_cert_b64_len = base64_encode_size(cert->encoded_len,
  584. BASE64_ENCODE_MULTILINE) + 1;
  585. ed_cert_b64 = tor_malloc_zero(ed_cert_b64_len);
  586. /* Base64 encode the encoded certificate. */
  587. if (base64_encode(ed_cert_b64, ed_cert_b64_len,
  588. (const char *) cert->encoded, cert->encoded_len,
  589. BASE64_ENCODE_MULTILINE) < 0) {
  590. log_err(LD_BUG, "Couldn't base64-encode ed22519 cert!");
  591. goto err;
  592. }
  593. /* Put everything together in a NUL terminated string. */
  594. tor_asprintf(cert_str_out,
  595. "-----BEGIN ED25519 CERT-----\n"
  596. "%s"
  597. "-----END ED25519 CERT-----",
  598. ed_cert_b64);
  599. /* Success! */
  600. ret = 0;
  601. err:
  602. tor_free(ed_cert_b64);
  603. return ret;
  604. }