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[] = "TLS 1.3, ";
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 const char *derived_secret_label = "derived secret";
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);
153 EVP_MD_CTX_free(mctx);
155 /* Generate the pre-extract secret */
156 if (!tls13_hkdf_expand(s, md, prevsecret,
157 (unsigned char *)derived_secret_label,
158 sizeof(derived_secret_label) - 1, hash,
159 preextractsec, mdlen))
162 prevsecret = preextractsec;
163 prevsecretlen = mdlen;
166 ret = EVP_PKEY_derive_init(pctx) <= 0
167 || EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY)
169 || EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
170 || EVP_PKEY_CTX_set1_hkdf_key(pctx, insecret, insecretlen) <= 0
171 || EVP_PKEY_CTX_set1_hkdf_salt(pctx, prevsecret, prevsecretlen)
173 || EVP_PKEY_derive(pctx, outsecret, &mdlen)
176 EVP_PKEY_CTX_free(pctx);
177 if (prevsecret == preextractsec)
178 OPENSSL_cleanse(preextractsec, mdlen);
183 * Given an input secret |insecret| of length |insecretlen| generate the
184 * handshake secret. This requires the early secret to already have been
185 * generated. Returns 1 on success 0 on failure.
187 int tls13_generate_handshake_secret(SSL *s, const unsigned char *insecret,
190 return tls13_generate_secret(s, ssl_handshake_md(s), s->early_secret,
191 insecret, insecretlen,
192 (unsigned char *)&s->handshake_secret);
196 * Given the handshake secret |prev| of length |prevlen| generate the master
197 * secret and store its length in |*secret_size|. Returns 1 on success 0 on
200 int tls13_generate_master_secret(SSL *s, unsigned char *out,
201 unsigned char *prev, size_t prevlen,
204 const EVP_MD *md = ssl_handshake_md(s);
206 *secret_size = EVP_MD_size(md);
207 return tls13_generate_secret(s, md, prev, NULL, 0, out);
211 * Generates the mac for the Finished message. Returns the length of the MAC or
214 size_t tls13_final_finish_mac(SSL *s, const char *str, size_t slen,
217 const EVP_MD *md = ssl_handshake_md(s);
218 unsigned char hash[EVP_MAX_MD_SIZE];
219 size_t hashlen, ret = 0;
220 EVP_PKEY *key = NULL;
221 EVP_MD_CTX *ctx = EVP_MD_CTX_new();
223 if (!ssl_handshake_hash(s, hash, sizeof(hash), &hashlen))
226 if (str == s->method->ssl3_enc->server_finished_label)
227 key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
228 s->server_finished_secret, hashlen);
230 key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
231 s->client_finished_secret, hashlen);
235 || EVP_DigestSignInit(ctx, NULL, md, NULL, key) <= 0
236 || EVP_DigestSignUpdate(ctx, hash, hashlen) <= 0
237 || EVP_DigestSignFinal(ctx, out, &hashlen) <= 0)
243 EVP_MD_CTX_free(ctx);
248 * There isn't really a key block in TLSv1.3, but we still need this function
249 * for initialising the cipher and hash. Returns 1 on success or 0 on failure.
251 int tls13_setup_key_block(SSL *s)
255 int mac_type = NID_undef;
257 s->session->cipher = s->s3->tmp.new_cipher;
258 if (!ssl_cipher_get_evp
259 (s->session, &c, &hash, &mac_type, NULL, NULL, 0)) {
260 SSLerr(SSL_F_TLS13_SETUP_KEY_BLOCK, SSL_R_CIPHER_OR_HASH_UNAVAILABLE);
264 s->s3->tmp.new_sym_enc = c;
265 s->s3->tmp.new_hash = hash;
270 static int derive_secret_key_and_iv(SSL *s, int send, const EVP_MD *md,
271 const EVP_CIPHER *ciph,
272 const unsigned char *insecret,
273 const unsigned char *hash,
274 const unsigned char *label,
275 size_t labellen, unsigned char *secret,
276 unsigned char *iv, EVP_CIPHER_CTX *ciph_ctx)
278 unsigned char key[EVP_MAX_KEY_LENGTH];
279 size_t ivlen, keylen, taglen;
280 size_t hashlen = EVP_MD_size(md);
282 if (!tls13_hkdf_expand(s, md, insecret, label, labellen, hash, secret,
284 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
288 /* TODO(size_t): convert me */
289 keylen = EVP_CIPHER_key_length(ciph);
290 if (EVP_CIPHER_mode(ciph) == EVP_CIPH_CCM_MODE) {
293 ivlen = EVP_CCM_TLS_IV_LEN;
294 if (s->s3->tmp.new_cipher == NULL) {
295 /* We've not selected a cipher yet - we must be doing early data */
296 algenc = s->session->cipher->algorithm_enc;
298 algenc = s->s3->tmp.new_cipher->algorithm_enc;
300 if (algenc & (SSL_AES128CCM8 | SSL_AES256CCM8))
301 taglen = EVP_CCM8_TLS_TAG_LEN;
303 taglen = EVP_CCM_TLS_TAG_LEN;
305 ivlen = EVP_CIPHER_iv_length(ciph);
309 if (!tls13_derive_key(s, md, secret, key, keylen)
310 || !tls13_derive_iv(s, md, secret, iv, ivlen)) {
311 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
315 if (EVP_CipherInit_ex(ciph_ctx, ciph, NULL, NULL, NULL, send) <= 0
316 || !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
317 || (taglen != 0 && !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_TAG,
319 || EVP_CipherInit_ex(ciph_ctx, NULL, NULL, key, NULL, -1) <= 0) {
320 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_EVP_LIB);
324 #ifdef OPENSSL_SSL_TRACE_CRYPTO
325 if (s->msg_callback) {
326 int wh = send ? TLS1_RT_CRYPTO_WRITE : 0;
329 s->msg_callback(2, s->version, wh | TLS1_RT_CRYPTO_KEY,
330 key, ciph->key_len, s, s->msg_callback_arg);
332 wh |= TLS1_RT_CRYPTO_IV;
333 s->msg_callback(2, s->version, wh, iv, ivlen, s,
334 s->msg_callback_arg);
340 OPENSSL_cleanse(key, sizeof(key));
344 int tls13_change_cipher_state(SSL *s, int which)
346 static const unsigned char client_early_traffic[] =
347 "client early traffic secret";
348 static const unsigned char client_handshake_traffic[] =
349 "client handshake traffic secret";
350 static const unsigned char client_application_traffic[] =
351 "client application traffic secret";
352 static const unsigned char server_handshake_traffic[] =
353 "server handshake traffic secret";
354 static const unsigned char server_application_traffic[] =
355 "server application traffic secret";
356 static const unsigned char resumption_master_secret[] =
357 "resumption master secret";
359 unsigned char secret[EVP_MAX_MD_SIZE];
360 unsigned char hashval[EVP_MAX_MD_SIZE];
361 unsigned char *hash = hashval;
362 unsigned char *insecret;
363 unsigned char *finsecret = NULL;
364 const char *log_label = NULL;
365 EVP_CIPHER_CTX *ciph_ctx;
366 size_t finsecretlen = 0;
367 const unsigned char *label;
368 size_t labellen, hashlen = 0;
370 const EVP_MD *md = NULL;
371 const EVP_CIPHER *cipher = NULL;
373 if (which & SSL3_CC_READ) {
374 if (s->enc_read_ctx != NULL) {
375 EVP_CIPHER_CTX_reset(s->enc_read_ctx);
377 s->enc_read_ctx = EVP_CIPHER_CTX_new();
378 if (s->enc_read_ctx == NULL) {
379 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
383 ciph_ctx = s->enc_read_ctx;
386 RECORD_LAYER_reset_read_sequence(&s->rlayer);
388 if (s->enc_write_ctx != NULL) {
389 EVP_CIPHER_CTX_reset(s->enc_write_ctx);
391 s->enc_write_ctx = EVP_CIPHER_CTX_new();
392 if (s->enc_write_ctx == NULL) {
393 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
397 ciph_ctx = s->enc_write_ctx;
400 RECORD_LAYER_reset_write_sequence(&s->rlayer);
403 if (((which & SSL3_CC_CLIENT) && (which & SSL3_CC_WRITE))
404 || ((which & SSL3_CC_SERVER) && (which & SSL3_CC_READ))) {
405 if (which & SSL3_CC_EARLY) {
406 EVP_MD_CTX *mdctx = NULL;
409 unsigned int hashlenui;
410 const SSL_CIPHER *sslcipher = SSL_SESSION_get0_cipher(s->session);
412 insecret = s->early_secret;
413 label = client_early_traffic;
414 labellen = sizeof(client_early_traffic) - 1;
415 log_label = CLIENT_EARLY_LABEL;
417 handlen = BIO_get_mem_data(s->s3->handshake_buffer, &hdata);
419 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE,
420 SSL_R_BAD_HANDSHAKE_LENGTH);
423 if (sslcipher == NULL) {
424 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
429 * We need to calculate the handshake digest using the digest from
430 * the session. We haven't yet selected our ciphersuite so we can't
431 * use ssl_handshake_md().
433 mdctx = EVP_MD_CTX_new();
435 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
438 cipher = EVP_get_cipherbynid(SSL_CIPHER_get_cipher_nid(sslcipher));
439 md = ssl_md(sslcipher->algorithm2);
440 if (md == NULL || !EVP_DigestInit_ex(mdctx, md, NULL)
441 || !EVP_DigestUpdate(mdctx, hdata, handlen)
442 || !EVP_DigestFinal_ex(mdctx, hashval, &hashlenui)) {
443 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
444 EVP_MD_CTX_free(mdctx);
448 EVP_MD_CTX_free(mdctx);
449 } else if (which & SSL3_CC_HANDSHAKE) {
450 insecret = s->handshake_secret;
451 finsecret = s->client_finished_secret;
452 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
453 label = client_handshake_traffic;
454 labellen = sizeof(client_handshake_traffic) - 1;
455 log_label = CLIENT_HANDSHAKE_LABEL;
457 * The hanshake hash used for the server read/client write handshake
458 * traffic secret is the same as the hash for the server
459 * write/client read handshake traffic secret. However, if we
460 * processed early data then we delay changing the server
461 * read/client write cipher state until later, and the handshake
462 * hashes have moved on. Therefore we use the value saved earlier
463 * when we did the server write/client read change cipher state.
465 hash = s->handshake_traffic_hash;
467 insecret = s->master_secret;
468 label = client_application_traffic;
469 labellen = sizeof(client_application_traffic) - 1;
470 log_label = CLIENT_APPLICATION_LABEL;
472 * For this we only use the handshake hashes up until the server
473 * Finished hash. We do not include the client's Finished, which is
474 * what ssl_handshake_hash() would give us. Instead we use the
475 * previously saved value.
477 hash = s->server_finished_hash;
480 /* Early data never applies to client-read/server-write */
481 if (which & SSL3_CC_HANDSHAKE) {
482 insecret = s->handshake_secret;
483 finsecret = s->server_finished_secret;
484 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
485 label = server_handshake_traffic;
486 labellen = sizeof(server_handshake_traffic) - 1;
487 log_label = SERVER_HANDSHAKE_LABEL;
489 insecret = s->master_secret;
490 label = server_application_traffic;
491 labellen = sizeof(server_application_traffic) - 1;
492 log_label = SERVER_APPLICATION_LABEL;
496 if (!(which & SSL3_CC_EARLY)) {
497 md = ssl_handshake_md(s);
498 cipher = s->s3->tmp.new_sym_enc;
499 if (!ssl3_digest_cached_records(s, 1)
500 || !ssl_handshake_hash(s, hashval, sizeof(hashval), &hashlen)) {
501 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
507 * Save the hash of handshakes up to now for use when we calculate the
508 * client application traffic secret
510 if (label == server_application_traffic)
511 memcpy(s->server_finished_hash, hashval, hashlen);
513 if (label == server_handshake_traffic)
514 memcpy(s->handshake_traffic_hash, hashval, hashlen);
516 if (label == client_application_traffic) {
518 * We also create the resumption master secret, but this time use the
519 * hash for the whole handshake including the Client Finished
521 if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
522 resumption_master_secret,
523 sizeof(resumption_master_secret) - 1,
524 hashval, s->session->master_key, hashlen)) {
525 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
528 s->session->master_key_length = hashlen;
531 if (!derive_secret_key_and_iv(s, which & SSL3_CC_WRITE, md, cipher,
532 insecret, hash, label, labellen, secret, iv,
537 if (label == server_application_traffic)
538 memcpy(s->server_app_traffic_secret, secret, hashlen);
539 else if (label == client_application_traffic)
540 memcpy(s->client_app_traffic_secret, secret, hashlen);
542 if (!ssl_log_secret(s, log_label, secret, hashlen)) {
543 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
547 if (finsecret != NULL
548 && !tls13_derive_finishedkey(s, ssl_handshake_md(s), secret,
549 finsecret, finsecretlen)) {
550 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
556 OPENSSL_cleanse(secret, sizeof(secret));
560 int tls13_update_key(SSL *s, int send)
562 static const unsigned char application_traffic[] =
563 "application traffic secret";
564 const EVP_MD *md = ssl_handshake_md(s);
565 size_t hashlen = EVP_MD_size(md);
566 unsigned char *insecret, *iv;
567 unsigned char secret[EVP_MAX_MD_SIZE];
568 EVP_CIPHER_CTX *ciph_ctx;
571 if (s->server == send)
572 insecret = s->server_app_traffic_secret;
574 insecret = s->client_app_traffic_secret;
578 ciph_ctx = s->enc_write_ctx;
579 RECORD_LAYER_reset_write_sequence(&s->rlayer);
582 ciph_ctx = s->enc_read_ctx;
583 RECORD_LAYER_reset_read_sequence(&s->rlayer);
586 if (!derive_secret_key_and_iv(s, send, ssl_handshake_md(s),
587 s->s3->tmp.new_sym_enc, insecret, NULL,
589 sizeof(application_traffic) - 1, secret, iv,
593 memcpy(insecret, secret, hashlen);
597 OPENSSL_cleanse(secret, sizeof(secret));
601 int tls13_alert_code(int code)
603 if (code == SSL_AD_MISSING_EXTENSION || code == SSL_AD_END_OF_EARLY_DATA)
606 return tls1_alert_code(code);