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);
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 sending, 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, sending) <= 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);
326 OPENSSL_cleanse(key, sizeof(key));
330 int tls13_change_cipher_state(SSL *s, int which)
332 static const unsigned char client_early_traffic[] = "c e traffic";
333 static const unsigned char client_handshake_traffic[] = "c hs traffic";
334 static const unsigned char client_application_traffic[] = "c ap traffic";
335 static const unsigned char server_handshake_traffic[] = "s hs traffic";
336 static const unsigned char server_application_traffic[] = "s ap traffic";
337 static const unsigned char resumption_master_secret[] = "res master";
339 unsigned char secret[EVP_MAX_MD_SIZE];
340 unsigned char hashval[EVP_MAX_MD_SIZE];
341 unsigned char *hash = hashval;
342 unsigned char *insecret;
343 unsigned char *finsecret = NULL;
344 const char *log_label = NULL;
345 EVP_CIPHER_CTX *ciph_ctx;
346 size_t finsecretlen = 0;
347 const unsigned char *label;
348 size_t labellen, hashlen = 0;
350 const EVP_MD *md = NULL;
351 const EVP_CIPHER *cipher = NULL;
353 if (which & SSL3_CC_READ) {
354 if (s->enc_read_ctx != NULL) {
355 EVP_CIPHER_CTX_reset(s->enc_read_ctx);
357 s->enc_read_ctx = EVP_CIPHER_CTX_new();
358 if (s->enc_read_ctx == NULL) {
359 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
363 ciph_ctx = s->enc_read_ctx;
366 RECORD_LAYER_reset_read_sequence(&s->rlayer);
368 if (s->enc_write_ctx != NULL) {
369 EVP_CIPHER_CTX_reset(s->enc_write_ctx);
371 s->enc_write_ctx = EVP_CIPHER_CTX_new();
372 if (s->enc_write_ctx == NULL) {
373 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
377 ciph_ctx = s->enc_write_ctx;
380 RECORD_LAYER_reset_write_sequence(&s->rlayer);
383 if (((which & SSL3_CC_CLIENT) && (which & SSL3_CC_WRITE))
384 || ((which & SSL3_CC_SERVER) && (which & SSL3_CC_READ))) {
385 if (which & SSL3_CC_EARLY) {
386 EVP_MD_CTX *mdctx = NULL;
389 unsigned int hashlenui;
390 const SSL_CIPHER *sslcipher = SSL_SESSION_get0_cipher(s->session);
392 insecret = s->early_secret;
393 label = client_early_traffic;
394 labellen = sizeof(client_early_traffic) - 1;
395 log_label = CLIENT_EARLY_LABEL;
397 handlen = BIO_get_mem_data(s->s3->handshake_buffer, &hdata);
399 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE,
400 SSL_R_BAD_HANDSHAKE_LENGTH);
403 if (sslcipher == NULL) {
404 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
409 * We need to calculate the handshake digest using the digest from
410 * the session. We haven't yet selected our ciphersuite so we can't
411 * use ssl_handshake_md().
413 mdctx = EVP_MD_CTX_new();
415 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
418 cipher = EVP_get_cipherbynid(SSL_CIPHER_get_cipher_nid(sslcipher));
419 md = ssl_md(sslcipher->algorithm2);
420 if (md == NULL || !EVP_DigestInit_ex(mdctx, md, NULL)
421 || !EVP_DigestUpdate(mdctx, hdata, handlen)
422 || !EVP_DigestFinal_ex(mdctx, hashval, &hashlenui)) {
423 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
424 EVP_MD_CTX_free(mdctx);
428 EVP_MD_CTX_free(mdctx);
429 } else if (which & SSL3_CC_HANDSHAKE) {
430 insecret = s->handshake_secret;
431 finsecret = s->client_finished_secret;
432 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
433 label = client_handshake_traffic;
434 labellen = sizeof(client_handshake_traffic) - 1;
435 log_label = CLIENT_HANDSHAKE_LABEL;
437 * The handshake hash used for the server read/client write handshake
438 * traffic secret is the same as the hash for the server
439 * write/client read handshake traffic secret. However, if we
440 * processed early data then we delay changing the server
441 * read/client write cipher state until later, and the handshake
442 * hashes have moved on. Therefore we use the value saved earlier
443 * when we did the server write/client read change cipher state.
445 hash = s->handshake_traffic_hash;
447 insecret = s->master_secret;
448 label = client_application_traffic;
449 labellen = sizeof(client_application_traffic) - 1;
450 log_label = CLIENT_APPLICATION_LABEL;
452 * For this we only use the handshake hashes up until the server
453 * Finished hash. We do not include the client's Finished, which is
454 * what ssl_handshake_hash() would give us. Instead we use the
455 * previously saved value.
457 hash = s->server_finished_hash;
460 /* Early data never applies to client-read/server-write */
461 if (which & SSL3_CC_HANDSHAKE) {
462 insecret = s->handshake_secret;
463 finsecret = s->server_finished_secret;
464 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
465 label = server_handshake_traffic;
466 labellen = sizeof(server_handshake_traffic) - 1;
467 log_label = SERVER_HANDSHAKE_LABEL;
469 insecret = s->master_secret;
470 label = server_application_traffic;
471 labellen = sizeof(server_application_traffic) - 1;
472 log_label = SERVER_APPLICATION_LABEL;
476 if (!(which & SSL3_CC_EARLY)) {
477 md = ssl_handshake_md(s);
478 cipher = s->s3->tmp.new_sym_enc;
479 if (!ssl3_digest_cached_records(s, 1)
480 || !ssl_handshake_hash(s, hashval, sizeof(hashval), &hashlen)) {
481 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
487 * Save the hash of handshakes up to now for use when we calculate the
488 * client application traffic secret
490 if (label == server_application_traffic)
491 memcpy(s->server_finished_hash, hashval, hashlen);
493 if (label == server_handshake_traffic)
494 memcpy(s->handshake_traffic_hash, hashval, hashlen);
496 if (label == client_application_traffic) {
498 * We also create the resumption master secret, but this time use the
499 * hash for the whole handshake including the Client Finished
501 if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
502 resumption_master_secret,
503 sizeof(resumption_master_secret) - 1,
504 hashval, s->session->master_key, hashlen)) {
505 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
508 s->session->master_key_length = hashlen;
511 if (!derive_secret_key_and_iv(s, which & SSL3_CC_WRITE, md, cipher,
512 insecret, hash, label, labellen, secret, iv,
517 if (label == server_application_traffic)
518 memcpy(s->server_app_traffic_secret, secret, hashlen);
519 else if (label == client_application_traffic)
520 memcpy(s->client_app_traffic_secret, secret, hashlen);
522 if (!ssl_log_secret(s, log_label, secret, hashlen)) {
523 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
527 if (finsecret != NULL
528 && !tls13_derive_finishedkey(s, ssl_handshake_md(s), secret,
529 finsecret, finsecretlen)) {
530 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
536 OPENSSL_cleanse(secret, sizeof(secret));
540 int tls13_update_key(SSL *s, int sending)
542 static const unsigned char application_traffic[] = "traffic upd";
543 const EVP_MD *md = ssl_handshake_md(s);
544 size_t hashlen = EVP_MD_size(md);
545 unsigned char *insecret, *iv;
546 unsigned char secret[EVP_MAX_MD_SIZE];
547 EVP_CIPHER_CTX *ciph_ctx;
550 if (s->server == sending)
551 insecret = s->server_app_traffic_secret;
553 insecret = s->client_app_traffic_secret;
557 ciph_ctx = s->enc_write_ctx;
558 RECORD_LAYER_reset_write_sequence(&s->rlayer);
561 ciph_ctx = s->enc_read_ctx;
562 RECORD_LAYER_reset_read_sequence(&s->rlayer);
565 if (!derive_secret_key_and_iv(s, sending, ssl_handshake_md(s),
566 s->s3->tmp.new_sym_enc, insecret, NULL,
568 sizeof(application_traffic) - 1, secret, iv,
572 memcpy(insecret, secret, hashlen);
576 OPENSSL_cleanse(secret, sizeof(secret));
580 int tls13_alert_code(int code)
582 if (code == SSL_AD_MISSING_EXTENSION)
585 return tls1_alert_code(code);