torcert.c 23 KB

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  1. /* Copyright (c) 2014-2016, 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. uint8_t *res;
  271. rsa_ed_crosscert_t *cc = rsa_ed_crosscert_new();
  272. memcpy(cc->ed_key, ed_key->pubkey, ED25519_PUBKEY_LEN);
  273. cc->expiration = (uint32_t) CEIL_DIV(expires, 3600);
  274. cc->sig_len = crypto_pk_keysize(rsa_key);
  275. rsa_ed_crosscert_setlen_sig(cc, crypto_pk_keysize(rsa_key));
  276. ssize_t alloc_sz = rsa_ed_crosscert_encoded_len(cc);
  277. tor_assert(alloc_sz > 0);
  278. res = tor_malloc_zero(alloc_sz);
  279. ssize_t sz = rsa_ed_crosscert_encode(res, alloc_sz, cc);
  280. tor_assert(sz > 0 && sz <= alloc_sz);
  281. crypto_digest_t *d = crypto_digest256_new(DIGEST_SHA256);
  282. crypto_digest_add_bytes(d, RSA_ED_CROSSCERT_PREFIX,
  283. strlen(RSA_ED_CROSSCERT_PREFIX));
  284. const int signed_part_len = 32 + 4;
  285. crypto_digest_add_bytes(d, (char*)res, signed_part_len);
  286. uint8_t digest[DIGEST256_LEN];
  287. crypto_digest_get_digest(d, (char*)digest, sizeof(digest));
  288. crypto_digest_free(d);
  289. int siglen = crypto_pk_private_sign(rsa_key,
  290. (char*)rsa_ed_crosscert_getarray_sig(cc),
  291. rsa_ed_crosscert_getlen_sig(cc),
  292. (char*)digest, sizeof(digest));
  293. tor_assert(siglen > 0 && siglen <= (int)crypto_pk_keysize(rsa_key));
  294. tor_assert(siglen <= UINT8_MAX);
  295. cc->sig_len = siglen;
  296. rsa_ed_crosscert_setlen_sig(cc, siglen);
  297. sz = rsa_ed_crosscert_encode(res, alloc_sz, cc);
  298. rsa_ed_crosscert_free(cc);
  299. *cert = res;
  300. return sz;
  301. }
  302. /**
  303. * Check whether the <b>crosscert_len</b> byte certificate in <b>crosscert</b>
  304. * is in fact a correct cross-certification of <b>master_key</b> using
  305. * the RSA key <b>rsa_id_key</b>.
  306. *
  307. * Also reject the certificate if it expired before
  308. * <b>reject_if_expired_before</b>.
  309. *
  310. * Return 0 on success, negative on failure.
  311. */
  312. int
  313. rsa_ed25519_crosscert_check(const uint8_t *crosscert,
  314. const size_t crosscert_len,
  315. const crypto_pk_t *rsa_id_key,
  316. const ed25519_public_key_t *master_key,
  317. const time_t reject_if_expired_before)
  318. {
  319. rsa_ed_crosscert_t *cc = NULL;
  320. int rv;
  321. #define ERR(code, s) \
  322. do { \
  323. log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL, \
  324. "Received a bad RSA->Ed25519 crosscert: %s", \
  325. (s)); \
  326. rv = (code); \
  327. goto err; \
  328. } while (0)
  329. if (BUG(crypto_pk_keysize(rsa_id_key) > PK_BYTES))
  330. return -1;
  331. if (BUG(!crosscert))
  332. return -1;
  333. ssize_t parsed_len = rsa_ed_crosscert_parse(&cc, crosscert, crosscert_len);
  334. if (parsed_len < 0 || crosscert_len != (size_t)parsed_len) {
  335. ERR(-2, "Unparseable or overlong crosscert");
  336. }
  337. if (tor_memneq(rsa_ed_crosscert_getarray_ed_key(cc),
  338. master_key->pubkey,
  339. ED25519_PUBKEY_LEN)) {
  340. ERR(-3, "Crosscert did not match Ed25519 key");
  341. }
  342. const uint32_t expiration_date = rsa_ed_crosscert_get_expiration(cc);
  343. const uint64_t expiration_time = expiration_date * 3600;
  344. if (reject_if_expired_before < 0 ||
  345. expiration_time < (uint64_t)reject_if_expired_before) {
  346. ERR(-4, "Crosscert is expired");
  347. }
  348. const uint8_t *eos = rsa_ed_crosscert_get_end_of_signed(cc);
  349. const uint8_t *sig = rsa_ed_crosscert_getarray_sig(cc);
  350. const uint8_t siglen = rsa_ed_crosscert_get_sig_len(cc);
  351. tor_assert(eos >= crosscert);
  352. tor_assert((size_t)(eos - crosscert) <= crosscert_len);
  353. tor_assert(siglen == rsa_ed_crosscert_getlen_sig(cc));
  354. /* Compute the digest */
  355. uint8_t digest[DIGEST256_LEN];
  356. crypto_digest_t *d = crypto_digest256_new(DIGEST_SHA256);
  357. crypto_digest_add_bytes(d, RSA_ED_CROSSCERT_PREFIX,
  358. strlen(RSA_ED_CROSSCERT_PREFIX));
  359. crypto_digest_add_bytes(d, (char*)crosscert, eos-crosscert);
  360. crypto_digest_get_digest(d, (char*)digest, sizeof(digest));
  361. crypto_digest_free(d);
  362. /* Now check the signature */
  363. uint8_t signed_[PK_BYTES];
  364. int signed_len = crypto_pk_public_checksig(rsa_id_key,
  365. (char*)signed_, sizeof(signed_),
  366. (char*)sig, siglen);
  367. if (signed_len < DIGEST256_LEN) {
  368. ERR(-5, "Bad signature, or length of signed data not as expected");
  369. }
  370. if (tor_memneq(digest, signed_, DIGEST256_LEN)) {
  371. ERR(-6, "The signature was good, but it didn't match the data");
  372. }
  373. rv = 0;
  374. err:
  375. rsa_ed_crosscert_free(cc);
  376. return rv;
  377. }
  378. /** Construct and return a new empty or_handshake_certs object */
  379. or_handshake_certs_t *
  380. or_handshake_certs_new(void)
  381. {
  382. return tor_malloc_zero(sizeof(or_handshake_certs_t));
  383. }
  384. /** Release all storage held in <b>certs</b> */
  385. void
  386. or_handshake_certs_free(or_handshake_certs_t *certs)
  387. {
  388. if (!certs)
  389. return;
  390. tor_x509_cert_free(certs->auth_cert);
  391. tor_x509_cert_free(certs->link_cert);
  392. tor_x509_cert_free(certs->id_cert);
  393. tor_cert_free(certs->ed_id_sign);
  394. tor_cert_free(certs->ed_sign_link);
  395. tor_cert_free(certs->ed_sign_auth);
  396. tor_free(certs->ed_rsa_crosscert);
  397. memwipe(certs, 0xBD, sizeof(*certs));
  398. tor_free(certs);
  399. }
  400. #undef ERR
  401. #define ERR(s) \
  402. do { \
  403. log_fn(severity, LD_PROTOCOL, \
  404. "Received a bad CERTS cell: %s", \
  405. (s)); \
  406. return 0; \
  407. } while (0)
  408. int
  409. or_handshake_certs_rsa_ok(int severity,
  410. or_handshake_certs_t *certs,
  411. tor_tls_t *tls,
  412. time_t now)
  413. {
  414. tor_x509_cert_t *link_cert = certs->link_cert;
  415. tor_x509_cert_t *auth_cert = certs->auth_cert;
  416. tor_x509_cert_t *id_cert = certs->id_cert;
  417. if (certs->started_here) {
  418. if (! (id_cert && link_cert))
  419. ERR("The certs we wanted (ID, Link) were missing");
  420. if (! tor_tls_cert_matches_key(tls, link_cert))
  421. ERR("The link certificate didn't match the TLS public key");
  422. if (! tor_tls_cert_is_valid(severity, link_cert, id_cert, now, 0))
  423. ERR("The link certificate was not valid");
  424. if (! tor_tls_cert_is_valid(severity, id_cert, id_cert, now, 1))
  425. ERR("The ID certificate was not valid");
  426. } else {
  427. if (! (id_cert && auth_cert))
  428. ERR("The certs we wanted (ID, Auth) were missing");
  429. if (! tor_tls_cert_is_valid(LOG_PROTOCOL_WARN, auth_cert, id_cert, now, 1))
  430. ERR("The authentication certificate was not valid");
  431. if (! tor_tls_cert_is_valid(LOG_PROTOCOL_WARN, id_cert, id_cert, now, 1))
  432. ERR("The ID certificate was not valid");
  433. }
  434. return 1;
  435. }
  436. /** Check all the ed25519 certificates in <b>certs</b> against each other, and
  437. * against the peer certificate in <b>tls</b> if appropriate. On success,
  438. * return 0; on failure, return a negative value and warn at level
  439. * <b>severity</b> */
  440. int
  441. or_handshake_certs_ed25519_ok(int severity,
  442. or_handshake_certs_t *certs,
  443. tor_tls_t *tls,
  444. time_t now)
  445. {
  446. ed25519_checkable_t check[10];
  447. unsigned n_checkable = 0;
  448. time_t expiration = TIME_MAX;
  449. #define ADDCERT(cert, pk) \
  450. do { \
  451. tor_assert(n_checkable < ARRAY_LENGTH(check)); \
  452. if (tor_cert_get_checkable_sig(&check[n_checkable++], cert, pk, \
  453. &expiration) < 0) \
  454. ERR("Could not get checkable cert."); \
  455. } while (0)
  456. if (! certs->ed_id_sign || !certs->ed_id_sign->signing_key_included) {
  457. ERR("No Ed25519 signing key");
  458. }
  459. ADDCERT(certs->ed_id_sign, NULL);
  460. if (certs->started_here) {
  461. if (! certs->ed_sign_link)
  462. ERR("No Ed25519 link key");
  463. {
  464. /* check for a match with the TLS cert. */
  465. tor_x509_cert_t *peer_cert = tor_tls_get_peer_cert(tls);
  466. if (BUG(!peer_cert)) {
  467. /* This is a bug, because if we got to this point, we are a connection
  468. * that was initiated here, and we completed a TLS handshake. The
  469. * other side *must* have given us a certificate! */
  470. ERR("No x509 peer cert"); // LCOV_EXCL_LINE
  471. }
  472. const common_digests_t *peer_cert_digests =
  473. tor_x509_cert_get_cert_digests(peer_cert);
  474. int okay = tor_memeq(peer_cert_digests->d[DIGEST_SHA256],
  475. certs->ed_sign_link->signed_key.pubkey,
  476. DIGEST256_LEN);
  477. tor_x509_cert_free(peer_cert);
  478. if (!okay)
  479. ERR("Link certificate does not match TLS certificate");
  480. }
  481. ADDCERT(certs->ed_sign_link, &certs->ed_id_sign->signed_key);
  482. } else {
  483. if (! certs->ed_sign_auth)
  484. ERR("No Ed25519 link authentication key");
  485. ADDCERT(certs->ed_sign_auth, &certs->ed_id_sign->signed_key);
  486. }
  487. if (expiration < now) {
  488. ERR("At least one certificate expired.");
  489. }
  490. /* Okay, we've gotten ready to check all the Ed25519 certificates.
  491. * Now, we are going to check the RSA certificate's cross-certification
  492. * with the ED certificates.
  493. *
  494. * FFFF In the future, we might want to make this optional.
  495. */
  496. tor_x509_cert_t *rsa_id_cert = certs->id_cert;
  497. if (!rsa_id_cert) {
  498. ERR("Missing legacy RSA ID certificate");
  499. }
  500. if (! tor_tls_cert_is_valid(severity, rsa_id_cert, rsa_id_cert, now, 1)) {
  501. ERR("The legacy RSA ID certificate was not valid");
  502. }
  503. if (! certs->ed_rsa_crosscert) {
  504. ERR("Missing RSA->Ed25519 crosscert");
  505. }
  506. crypto_pk_t *rsa_id_key = tor_tls_cert_get_key(rsa_id_cert);
  507. if (!rsa_id_key) {
  508. ERR("RSA ID cert had no RSA key");
  509. }
  510. if (rsa_ed25519_crosscert_check(certs->ed_rsa_crosscert,
  511. certs->ed_rsa_crosscert_len,
  512. rsa_id_key,
  513. &certs->ed_id_sign->signing_key,
  514. now) < 0) {
  515. crypto_pk_free(rsa_id_key);
  516. ERR("Invalid RSA->Ed25519 crosscert");
  517. }
  518. crypto_pk_free(rsa_id_key);
  519. rsa_id_key = NULL;
  520. /* FFFF We could save a little time in the client case by queueing
  521. * this batch to check it later, along with the signature from the
  522. * AUTHENTICATE cell. That will change our data flow a bit, though,
  523. * so I say "postpone". */
  524. if (ed25519_checksig_batch(NULL, check, n_checkable) < 0) {
  525. ERR("At least one Ed25519 certificate was badly signed");
  526. }
  527. return 1;
  528. }
  529. /**
  530. * Check the Ed certificates and/or the RSA certificates, as appropriate. If
  531. * we obtained an Ed25519 identity, set *ed_id_out. If we obtained an RSA
  532. * identity, set *rs_id_out. Otherwise, set them both to NULL.
  533. */
  534. void
  535. or_handshake_certs_check_both(int severity,
  536. or_handshake_certs_t *certs,
  537. tor_tls_t *tls,
  538. time_t now,
  539. const ed25519_public_key_t **ed_id_out,
  540. const common_digests_t **rsa_id_out)
  541. {
  542. tor_assert(ed_id_out);
  543. tor_assert(rsa_id_out);
  544. *ed_id_out = NULL;
  545. *rsa_id_out = NULL;
  546. if (certs->ed_id_sign) {
  547. if (or_handshake_certs_ed25519_ok(severity, certs, tls, now)) {
  548. tor_assert(certs->ed_id_sign);
  549. tor_assert(certs->id_cert);
  550. *ed_id_out = &certs->ed_id_sign->signing_key;
  551. *rsa_id_out = tor_x509_cert_get_id_digests(certs->id_cert);
  552. /* If we reached this point, we did not look at any of the
  553. * subsidiary RSA certificates, so we'd better just remove them.
  554. */
  555. tor_x509_cert_free(certs->link_cert);
  556. tor_x509_cert_free(certs->auth_cert);
  557. certs->link_cert = certs->auth_cert = NULL;
  558. }
  559. /* We do _not_ fall through here. If you provided us Ed25519
  560. * certificates, we expect to verify them! */
  561. } else {
  562. /* No ed25519 keys given in the CERTS cell */
  563. if (or_handshake_certs_rsa_ok(severity, certs, tls, now)) {
  564. *rsa_id_out = tor_x509_cert_get_id_digests(certs->id_cert);
  565. }
  566. }
  567. }
  568. /* === ENCODING === */
  569. /* Encode the ed25519 certificate <b>cert</b> and put the newly allocated
  570. * string in <b>cert_str_out</b>. Return 0 on success else a negative value. */
  571. int
  572. tor_cert_encode_ed22519(const tor_cert_t *cert, char **cert_str_out)
  573. {
  574. int ret = -1;
  575. char *ed_cert_b64 = NULL;
  576. size_t ed_cert_b64_len;
  577. tor_assert(cert);
  578. tor_assert(cert_str_out);
  579. /* Get the encoded size and add the NUL byte. */
  580. ed_cert_b64_len = base64_encode_size(cert->encoded_len,
  581. BASE64_ENCODE_MULTILINE) + 1;
  582. ed_cert_b64 = tor_malloc_zero(ed_cert_b64_len);
  583. /* Base64 encode the encoded certificate. */
  584. if (base64_encode(ed_cert_b64, ed_cert_b64_len,
  585. (const char *) cert->encoded, cert->encoded_len,
  586. BASE64_ENCODE_MULTILINE) < 0) {
  587. log_err(LD_BUG, "Couldn't base64-encode ed22519 cert!");
  588. goto err;
  589. }
  590. /* Put everything together in a NUL terminated string. */
  591. tor_asprintf(cert_str_out,
  592. "-----BEGIN ED25519 CERT-----\n"
  593. "%s"
  594. "-----END ED25519 CERT-----",
  595. ed_cert_b64);
  596. /* Success! */
  597. ret = 0;
  598. err:
  599. tor_free(ed_cert_b64);
  600. return ret;
  601. }