2 * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
12 #include <openssl/evp.h>
13 #include <openssl/kdf.h>
15 #define TLS13_MAX_LABEL_LEN 246
17 /* Always filled with zeros */
18 static const unsigned char default_zeros[EVP_MAX_MD_SIZE];
21 * Given a |secret|; a |label| of length |labellen|; and a |hash| of the
22 * handshake messages, derive a new secret |outlen| bytes long and store it in
23 * the location pointed to be |out|. The |hash| value may be NULL. Returns 1 on
24 * success 0 on failure.
26 int tls13_hkdf_expand(SSL *s, const EVP_MD *md, const unsigned char *secret,
27 const unsigned char *label, size_t labellen,
28 const unsigned char *hash,
29 unsigned char *out, size_t outlen)
31 const unsigned char label_prefix[] = "tls13 ";
32 EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
37 * 2 bytes for length of whole HkdfLabel + 1 byte for length of combined
38 * prefix and label + bytes for the label itself + bytes for the hash
40 unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t) +
41 + sizeof(label_prefix) + TLS13_MAX_LABEL_LEN
48 hashlen = EVP_MD_size(md);
50 if (!WPACKET_init_static_len(&pkt, hkdflabel, sizeof(hkdflabel), 0)
51 || !WPACKET_put_bytes_u16(&pkt, outlen)
52 || !WPACKET_start_sub_packet_u8(&pkt)
53 || !WPACKET_memcpy(&pkt, label_prefix, sizeof(label_prefix) - 1)
54 || !WPACKET_memcpy(&pkt, label, labellen)
55 || !WPACKET_close(&pkt)
56 || !WPACKET_sub_memcpy_u8(&pkt, hash, (hash == NULL) ? 0 : hashlen)
57 || !WPACKET_get_total_written(&pkt, &hkdflabellen)
58 || !WPACKET_finish(&pkt)) {
59 EVP_PKEY_CTX_free(pctx);
60 WPACKET_cleanup(&pkt);
64 ret = EVP_PKEY_derive_init(pctx) <= 0
65 || EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY)
67 || EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
68 || EVP_PKEY_CTX_set1_hkdf_key(pctx, secret, hashlen) <= 0
69 || EVP_PKEY_CTX_add1_hkdf_info(pctx, hkdflabel, hkdflabellen) <= 0
70 || EVP_PKEY_derive(pctx, out, &outlen) <= 0;
72 EVP_PKEY_CTX_free(pctx);
78 * Given a |secret| generate a |key| of length |keylen| bytes. Returns 1 on
79 * success 0 on failure.
81 int tls13_derive_key(SSL *s, const EVP_MD *md, const unsigned char *secret,
82 unsigned char *key, size_t keylen)
84 static const unsigned char keylabel[] = "key";
86 return tls13_hkdf_expand(s, md, secret, keylabel, sizeof(keylabel) - 1,
91 * Given a |secret| generate an |iv| of length |ivlen| bytes. Returns 1 on
92 * success 0 on failure.
94 int tls13_derive_iv(SSL *s, const EVP_MD *md, const unsigned char *secret,
95 unsigned char *iv, size_t ivlen)
97 static const unsigned char ivlabel[] = "iv";
99 return tls13_hkdf_expand(s, md, secret, ivlabel, sizeof(ivlabel) - 1,
103 int tls13_derive_finishedkey(SSL *s, const EVP_MD *md,
104 const unsigned char *secret,
105 unsigned char *fin, size_t finlen)
107 static const unsigned char finishedlabel[] = "finished";
109 return tls13_hkdf_expand(s, md, secret, finishedlabel,
110 sizeof(finishedlabel) - 1, NULL, fin, finlen);
114 * Given the previous secret |prevsecret| and a new input secret |insecret| of
115 * length |insecretlen|, generate a new secret and store it in the location
116 * pointed to by |outsecret|. Returns 1 on success 0 on failure.
118 int tls13_generate_secret(SSL *s, const EVP_MD *md,
119 const unsigned char *prevsecret,
120 const unsigned char *insecret,
122 unsigned char *outsecret)
124 size_t mdlen, prevsecretlen;
126 EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
127 static const char derived_secret_label[] = "derived";
128 unsigned char preextractsec[EVP_MAX_MD_SIZE];
133 mdlen = EVP_MD_size(md);
135 if (insecret == NULL) {
136 insecret = default_zeros;
139 if (prevsecret == NULL) {
140 prevsecret = default_zeros;
143 EVP_MD_CTX *mctx = EVP_MD_CTX_new();
144 unsigned char hash[EVP_MAX_MD_SIZE];
146 /* The pre-extract derive step uses a hash of no messages */
148 || EVP_DigestInit_ex(mctx, md, NULL) <= 0
149 || EVP_DigestFinal_ex(mctx, hash, NULL) <= 0) {
150 EVP_MD_CTX_free(mctx);
151 EVP_PKEY_CTX_free(pctx);
154 EVP_MD_CTX_free(mctx);
156 /* Generate the pre-extract secret */
157 if (!tls13_hkdf_expand(s, md, prevsecret,
158 (unsigned char *)derived_secret_label,
159 sizeof(derived_secret_label) - 1, hash,
160 preextractsec, mdlen)) {
161 EVP_PKEY_CTX_free(pctx);
165 prevsecret = preextractsec;
166 prevsecretlen = mdlen;
169 ret = EVP_PKEY_derive_init(pctx) <= 0
170 || EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY)
172 || EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
173 || EVP_PKEY_CTX_set1_hkdf_key(pctx, insecret, insecretlen) <= 0
174 || EVP_PKEY_CTX_set1_hkdf_salt(pctx, prevsecret, prevsecretlen)
176 || EVP_PKEY_derive(pctx, outsecret, &mdlen)
179 EVP_PKEY_CTX_free(pctx);
180 if (prevsecret == preextractsec)
181 OPENSSL_cleanse(preextractsec, mdlen);
186 * Given an input secret |insecret| of length |insecretlen| generate the
187 * handshake secret. This requires the early secret to already have been
188 * generated. Returns 1 on success 0 on failure.
190 int tls13_generate_handshake_secret(SSL *s, const unsigned char *insecret,
193 return tls13_generate_secret(s, ssl_handshake_md(s), s->early_secret,
194 insecret, insecretlen,
195 (unsigned char *)&s->handshake_secret);
199 * Given the handshake secret |prev| of length |prevlen| generate the master
200 * secret and store its length in |*secret_size|. Returns 1 on success 0 on
203 int tls13_generate_master_secret(SSL *s, unsigned char *out,
204 unsigned char *prev, size_t prevlen,
207 const EVP_MD *md = ssl_handshake_md(s);
209 *secret_size = EVP_MD_size(md);
210 return tls13_generate_secret(s, md, prev, NULL, 0, out);
214 * Generates the mac for the Finished message. Returns the length of the MAC or
217 size_t tls13_final_finish_mac(SSL *s, const char *str, size_t slen,
220 const EVP_MD *md = ssl_handshake_md(s);
221 unsigned char hash[EVP_MAX_MD_SIZE];
222 size_t hashlen, ret = 0;
223 EVP_PKEY *key = NULL;
224 EVP_MD_CTX *ctx = EVP_MD_CTX_new();
226 if (!ssl_handshake_hash(s, hash, sizeof(hash), &hashlen))
229 if (str == s->method->ssl3_enc->server_finished_label)
230 key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
231 s->server_finished_secret, hashlen);
233 key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
234 s->client_finished_secret, hashlen);
238 || EVP_DigestSignInit(ctx, NULL, md, NULL, key) <= 0
239 || EVP_DigestSignUpdate(ctx, hash, hashlen) <= 0
240 || EVP_DigestSignFinal(ctx, out, &hashlen) <= 0)
246 EVP_MD_CTX_free(ctx);
251 * There isn't really a key block in TLSv1.3, but we still need this function
252 * for initialising the cipher and hash. Returns 1 on success or 0 on failure.
254 int tls13_setup_key_block(SSL *s)
258 int mac_type = NID_undef;
260 s->session->cipher = s->s3->tmp.new_cipher;
261 if (!ssl_cipher_get_evp
262 (s->session, &c, &hash, &mac_type, NULL, NULL, 0)) {
263 SSLerr(SSL_F_TLS13_SETUP_KEY_BLOCK, SSL_R_CIPHER_OR_HASH_UNAVAILABLE);
267 s->s3->tmp.new_sym_enc = c;
268 s->s3->tmp.new_hash = hash;
273 static int derive_secret_key_and_iv(SSL *s, int sending, const EVP_MD *md,
274 const EVP_CIPHER *ciph,
275 const unsigned char *insecret,
276 const unsigned char *hash,
277 const unsigned char *label,
278 size_t labellen, unsigned char *secret,
279 unsigned char *iv, EVP_CIPHER_CTX *ciph_ctx)
281 unsigned char key[EVP_MAX_KEY_LENGTH];
282 size_t ivlen, keylen, taglen;
283 size_t hashlen = EVP_MD_size(md);
285 if (!tls13_hkdf_expand(s, md, insecret, label, labellen, hash, secret,
287 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
291 /* TODO(size_t): convert me */
292 keylen = EVP_CIPHER_key_length(ciph);
293 if (EVP_CIPHER_mode(ciph) == EVP_CIPH_CCM_MODE) {
296 ivlen = EVP_CCM_TLS_IV_LEN;
297 if (s->s3->tmp.new_cipher == NULL) {
298 /* We've not selected a cipher yet - we must be doing early data */
299 algenc = s->session->cipher->algorithm_enc;
301 algenc = s->s3->tmp.new_cipher->algorithm_enc;
303 if (algenc & (SSL_AES128CCM8 | SSL_AES256CCM8))
304 taglen = EVP_CCM8_TLS_TAG_LEN;
306 taglen = EVP_CCM_TLS_TAG_LEN;
308 ivlen = EVP_CIPHER_iv_length(ciph);
312 if (!tls13_derive_key(s, md, secret, key, keylen)
313 || !tls13_derive_iv(s, md, secret, iv, ivlen)) {
314 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
318 if (EVP_CipherInit_ex(ciph_ctx, ciph, NULL, NULL, NULL, sending) <= 0
319 || !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
320 || (taglen != 0 && !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_TAG,
322 || EVP_CipherInit_ex(ciph_ctx, NULL, NULL, key, NULL, -1) <= 0) {
323 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_EVP_LIB);
329 OPENSSL_cleanse(key, sizeof(key));
333 int tls13_change_cipher_state(SSL *s, int which)
335 static const unsigned char client_early_traffic[] = "c e traffic";
336 static const unsigned char client_handshake_traffic[] = "c hs traffic";
337 static const unsigned char client_application_traffic[] = "c ap traffic";
338 static const unsigned char server_handshake_traffic[] = "s hs traffic";
339 static const unsigned char server_application_traffic[] = "s ap traffic";
340 static const unsigned char exporter_master_secret[] = "exp master";
341 static const unsigned char resumption_master_secret[] = "res master";
343 unsigned char secret[EVP_MAX_MD_SIZE];
344 unsigned char hashval[EVP_MAX_MD_SIZE];
345 unsigned char *hash = hashval;
346 unsigned char *insecret;
347 unsigned char *finsecret = NULL;
348 const char *log_label = NULL;
349 EVP_CIPHER_CTX *ciph_ctx;
350 size_t finsecretlen = 0;
351 const unsigned char *label;
352 size_t labellen, hashlen = 0;
354 const EVP_MD *md = NULL;
355 const EVP_CIPHER *cipher = NULL;
357 if (which & SSL3_CC_READ) {
358 if (s->enc_read_ctx != NULL) {
359 EVP_CIPHER_CTX_reset(s->enc_read_ctx);
361 s->enc_read_ctx = EVP_CIPHER_CTX_new();
362 if (s->enc_read_ctx == NULL) {
363 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
367 ciph_ctx = s->enc_read_ctx;
370 RECORD_LAYER_reset_read_sequence(&s->rlayer);
372 if (s->enc_write_ctx != NULL) {
373 EVP_CIPHER_CTX_reset(s->enc_write_ctx);
375 s->enc_write_ctx = EVP_CIPHER_CTX_new();
376 if (s->enc_write_ctx == NULL) {
377 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
381 ciph_ctx = s->enc_write_ctx;
384 RECORD_LAYER_reset_write_sequence(&s->rlayer);
387 if (((which & SSL3_CC_CLIENT) && (which & SSL3_CC_WRITE))
388 || ((which & SSL3_CC_SERVER) && (which & SSL3_CC_READ))) {
389 if (which & SSL3_CC_EARLY) {
390 EVP_MD_CTX *mdctx = NULL;
393 unsigned int hashlenui;
394 const SSL_CIPHER *sslcipher = SSL_SESSION_get0_cipher(s->session);
396 insecret = s->early_secret;
397 label = client_early_traffic;
398 labellen = sizeof(client_early_traffic) - 1;
399 log_label = CLIENT_EARLY_LABEL;
401 handlen = BIO_get_mem_data(s->s3->handshake_buffer, &hdata);
403 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE,
404 SSL_R_BAD_HANDSHAKE_LENGTH);
407 if (sslcipher == NULL) {
408 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
413 * We need to calculate the handshake digest using the digest from
414 * the session. We haven't yet selected our ciphersuite so we can't
415 * use ssl_handshake_md().
417 mdctx = EVP_MD_CTX_new();
419 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
422 cipher = EVP_get_cipherbynid(SSL_CIPHER_get_cipher_nid(sslcipher));
423 md = ssl_md(sslcipher->algorithm2);
424 if (md == NULL || !EVP_DigestInit_ex(mdctx, md, NULL)
425 || !EVP_DigestUpdate(mdctx, hdata, handlen)
426 || !EVP_DigestFinal_ex(mdctx, hashval, &hashlenui)) {
427 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
428 EVP_MD_CTX_free(mdctx);
432 EVP_MD_CTX_free(mdctx);
433 } else if (which & SSL3_CC_HANDSHAKE) {
434 insecret = s->handshake_secret;
435 finsecret = s->client_finished_secret;
436 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
437 label = client_handshake_traffic;
438 labellen = sizeof(client_handshake_traffic) - 1;
439 log_label = CLIENT_HANDSHAKE_LABEL;
441 * The handshake hash used for the server read/client write handshake
442 * traffic secret is the same as the hash for the server
443 * write/client read handshake traffic secret. However, if we
444 * processed early data then we delay changing the server
445 * read/client write cipher state until later, and the handshake
446 * hashes have moved on. Therefore we use the value saved earlier
447 * when we did the server write/client read change cipher state.
449 hash = s->handshake_traffic_hash;
451 insecret = s->master_secret;
452 label = client_application_traffic;
453 labellen = sizeof(client_application_traffic) - 1;
454 log_label = CLIENT_APPLICATION_LABEL;
456 * For this we only use the handshake hashes up until the server
457 * Finished hash. We do not include the client's Finished, which is
458 * what ssl_handshake_hash() would give us. Instead we use the
459 * previously saved value.
461 hash = s->server_finished_hash;
464 /* Early data never applies to client-read/server-write */
465 if (which & SSL3_CC_HANDSHAKE) {
466 insecret = s->handshake_secret;
467 finsecret = s->server_finished_secret;
468 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
469 label = server_handshake_traffic;
470 labellen = sizeof(server_handshake_traffic) - 1;
471 log_label = SERVER_HANDSHAKE_LABEL;
473 insecret = s->master_secret;
474 label = server_application_traffic;
475 labellen = sizeof(server_application_traffic) - 1;
476 log_label = SERVER_APPLICATION_LABEL;
480 if (!(which & SSL3_CC_EARLY)) {
481 md = ssl_handshake_md(s);
482 cipher = s->s3->tmp.new_sym_enc;
483 if (!ssl3_digest_cached_records(s, 1)
484 || !ssl_handshake_hash(s, hashval, sizeof(hashval), &hashlen)) {
485 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
491 * Save the hash of handshakes up to now for use when we calculate the
492 * client application traffic secret
494 if (label == server_application_traffic)
495 memcpy(s->server_finished_hash, hashval, hashlen);
497 if (label == server_handshake_traffic)
498 memcpy(s->handshake_traffic_hash, hashval, hashlen);
500 if (label == client_application_traffic) {
502 * We also create the resumption master secret, but this time use the
503 * hash for the whole handshake including the Client Finished
505 if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
506 resumption_master_secret,
507 sizeof(resumption_master_secret) - 1,
508 hashval, s->session->master_key, hashlen)) {
509 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
512 s->session->master_key_length = hashlen;
514 /* Now we create the exporter master secret */
515 if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
516 exporter_master_secret,
517 sizeof(exporter_master_secret) - 1,
518 hash, s->exporter_master_secret, hashlen)) {
519 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
524 if (!derive_secret_key_and_iv(s, which & SSL3_CC_WRITE, md, cipher,
525 insecret, hash, label, labellen, secret, iv,
530 if (label == server_application_traffic)
531 memcpy(s->server_app_traffic_secret, secret, hashlen);
532 else if (label == client_application_traffic)
533 memcpy(s->client_app_traffic_secret, secret, hashlen);
535 if (!ssl_log_secret(s, log_label, secret, hashlen)) {
536 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
540 if (finsecret != NULL
541 && !tls13_derive_finishedkey(s, ssl_handshake_md(s), secret,
542 finsecret, finsecretlen)) {
543 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
549 OPENSSL_cleanse(secret, sizeof(secret));
553 int tls13_update_key(SSL *s, int sending)
555 static const unsigned char application_traffic[] = "traffic upd";
556 const EVP_MD *md = ssl_handshake_md(s);
557 size_t hashlen = EVP_MD_size(md);
558 unsigned char *insecret, *iv;
559 unsigned char secret[EVP_MAX_MD_SIZE];
560 EVP_CIPHER_CTX *ciph_ctx;
563 if (s->server == sending)
564 insecret = s->server_app_traffic_secret;
566 insecret = s->client_app_traffic_secret;
570 ciph_ctx = s->enc_write_ctx;
571 RECORD_LAYER_reset_write_sequence(&s->rlayer);
574 ciph_ctx = s->enc_read_ctx;
575 RECORD_LAYER_reset_read_sequence(&s->rlayer);
578 if (!derive_secret_key_and_iv(s, sending, ssl_handshake_md(s),
579 s->s3->tmp.new_sym_enc, insecret, NULL,
581 sizeof(application_traffic) - 1, secret, iv,
585 memcpy(insecret, secret, hashlen);
589 OPENSSL_cleanse(secret, sizeof(secret));
593 int tls13_alert_code(int code)
595 if (code == SSL_AD_MISSING_EXTENSION)
598 return tls1_alert_code(code);
601 int tls13_export_keying_material(SSL *s, unsigned char *out, size_t olen,
602 const char *label, size_t llen,
603 const unsigned char *context,
604 size_t contextlen, int use_context)
606 unsigned char exportsecret[EVP_MAX_MD_SIZE];
607 static const unsigned char exporterlabel[] = "exporter";
608 unsigned char hash[EVP_MAX_MD_SIZE];
609 const EVP_MD *md = ssl_handshake_md(s);
610 EVP_MD_CTX *ctx = EVP_MD_CTX_new();
611 unsigned int hashsize;
614 if (ctx == NULL || !SSL_is_init_finished(s))
620 if (EVP_DigestInit_ex(ctx, md, NULL) <= 0
621 || EVP_DigestUpdate(ctx, context, contextlen) <= 0
622 || EVP_DigestFinal_ex(ctx, hash, &hashsize) <= 0
623 || !tls13_hkdf_expand(s, md, s->exporter_master_secret,
624 (const unsigned char *)label, llen, NULL,
626 || !tls13_hkdf_expand(s, md, exportsecret, exporterlabel,
627 sizeof(exporterlabel) - 1, hash, out, olen))
632 EVP_MD_CTX_free(ctx);