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 WPACKET_cleanup(&pkt);
63 ret = EVP_PKEY_derive_init(pctx) <= 0
64 || EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY)
66 || EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
67 || EVP_PKEY_CTX_set1_hkdf_key(pctx, secret, hashlen) <= 0
68 || EVP_PKEY_CTX_add1_hkdf_info(pctx, hkdflabel, hkdflabellen) <= 0
69 || EVP_PKEY_derive(pctx, out, &outlen) <= 0;
71 EVP_PKEY_CTX_free(pctx);
77 * Given a |secret| generate a |key| of length |keylen| bytes. Returns 1 on
78 * success 0 on failure.
80 int tls13_derive_key(SSL *s, const unsigned char *secret, unsigned char *key,
83 static const unsigned char keylabel[] = "key";
85 return tls13_hkdf_expand(s, ssl_handshake_md(s), secret, keylabel,
86 sizeof(keylabel) - 1, NULL, key, keylen);
90 * Given a |secret| generate an |iv| of length |ivlen| bytes. Returns 1 on
91 * success 0 on failure.
93 int tls13_derive_iv(SSL *s, const unsigned char *secret, unsigned char *iv,
96 static const unsigned char ivlabel[] = "iv";
98 return tls13_hkdf_expand(s, ssl_handshake_md(s), secret, ivlabel,
99 sizeof(ivlabel) - 1, NULL, iv, ivlen);
102 int tls13_derive_finishedkey(SSL *s, const EVP_MD *md,
103 const unsigned char *secret,
104 unsigned char *fin, size_t finlen)
106 static const unsigned char finishedlabel[] = "finished";
108 return tls13_hkdf_expand(s, md, secret, finishedlabel,
109 sizeof(finishedlabel) - 1, NULL, fin, finlen);
113 * Given the previous secret |prevsecret| and a new input secret |insecret| of
114 * length |insecretlen|, generate a new secret and store it in the location
115 * pointed to by |outsecret|. Returns 1 on success 0 on failure.
117 int tls13_generate_secret(SSL *s, const EVP_MD *md,
118 const unsigned char *prevsecret,
119 const unsigned char *insecret,
121 unsigned char *outsecret)
123 size_t mdlen, prevsecretlen;
125 EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
130 mdlen = EVP_MD_size(md);
132 if (insecret == NULL) {
133 insecret = default_zeros;
136 if (prevsecret == NULL) {
137 prevsecret = default_zeros;
140 prevsecretlen = mdlen;
143 ret = EVP_PKEY_derive_init(pctx) <= 0
144 || EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY)
146 || EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
147 || EVP_PKEY_CTX_set1_hkdf_key(pctx, insecret, insecretlen) <= 0
148 || EVP_PKEY_CTX_set1_hkdf_salt(pctx, prevsecret, prevsecretlen)
150 || EVP_PKEY_derive(pctx, outsecret, &mdlen)
153 EVP_PKEY_CTX_free(pctx);
158 * Given an input secret |insecret| of length |insecretlen| generate the
159 * handshake secret. This requires the early secret to already have been
160 * generated. Returns 1 on success 0 on failure.
162 int tls13_generate_handshake_secret(SSL *s, const unsigned char *insecret,
165 return tls13_generate_secret(s, ssl_handshake_md(s), s->early_secret,
166 insecret, insecretlen,
167 (unsigned char *)&s->handshake_secret);
171 * Given the handshake secret |prev| of length |prevlen| generate the master
172 * secret and store its length in |*secret_size|. Returns 1 on success 0 on
175 int tls13_generate_master_secret(SSL *s, unsigned char *out,
176 unsigned char *prev, size_t prevlen,
179 const EVP_MD *md = ssl_handshake_md(s);
181 *secret_size = EVP_MD_size(md);
182 return tls13_generate_secret(s, md, prev, NULL, 0, out);
186 * Generates the mac for the Finished message. Returns the length of the MAC or
189 size_t tls13_final_finish_mac(SSL *s, const char *str, size_t slen,
192 const EVP_MD *md = ssl_handshake_md(s);
193 unsigned char hash[EVP_MAX_MD_SIZE];
194 size_t hashlen, ret = 0;
195 EVP_PKEY *key = NULL;
196 EVP_MD_CTX *ctx = EVP_MD_CTX_new();
198 if (!ssl_handshake_hash(s, hash, sizeof(hash), &hashlen))
201 if (str == s->method->ssl3_enc->server_finished_label)
202 key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
203 s->server_finished_secret, hashlen);
205 key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
206 s->client_finished_secret, hashlen);
210 || EVP_DigestSignInit(ctx, NULL, md, NULL, key) <= 0
211 || EVP_DigestSignUpdate(ctx, hash, hashlen) <= 0
212 || EVP_DigestSignFinal(ctx, out, &hashlen) <= 0)
218 EVP_MD_CTX_free(ctx);
223 * There isn't really a key block in TLSv1.3, but we still need this function
224 * for initialising the cipher and hash. Returns 1 on success or 0 on failure.
226 int tls13_setup_key_block(SSL *s)
230 int mac_type = NID_undef;
232 s->session->cipher = s->s3->tmp.new_cipher;
233 if (!ssl_cipher_get_evp
234 (s->session, &c, &hash, &mac_type, NULL, NULL, 0)) {
235 SSLerr(SSL_F_TLS13_SETUP_KEY_BLOCK, SSL_R_CIPHER_OR_HASH_UNAVAILABLE);
239 s->s3->tmp.new_sym_enc = c;
240 s->s3->tmp.new_hash = hash;
245 static int derive_secret_key_and_iv(SSL *s, int send,
246 const unsigned char *insecret,
247 const unsigned char *hash,
248 const unsigned char *label,
249 size_t labellen, unsigned char *secret,
250 unsigned char *iv, EVP_CIPHER_CTX *ciph_ctx)
252 unsigned char key[EVP_MAX_KEY_LENGTH];
253 size_t ivlen, keylen, taglen;
254 const EVP_MD *md = ssl_handshake_md(s);
255 size_t hashlen = EVP_MD_size(md);
256 const EVP_CIPHER *ciph = s->s3->tmp.new_sym_enc;
258 if (!tls13_hkdf_expand(s, md, insecret, label, labellen, hash, secret,
260 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
264 /* TODO(size_t): convert me */
265 keylen = EVP_CIPHER_key_length(ciph);
266 if (EVP_CIPHER_mode(ciph) == EVP_CIPH_CCM_MODE) {
267 ivlen = EVP_CCM_TLS_IV_LEN;
268 if (s->s3->tmp.new_cipher->algorithm_enc
269 & (SSL_AES128CCM8 | SSL_AES256CCM8))
270 taglen = EVP_CCM8_TLS_TAG_LEN;
272 taglen = EVP_CCM_TLS_TAG_LEN;
274 ivlen = EVP_CIPHER_iv_length(ciph);
278 if (!tls13_derive_key(s, secret, key, keylen)
279 || !tls13_derive_iv(s, secret, iv, ivlen)) {
280 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_INTERNAL_ERROR);
284 if (EVP_CipherInit_ex(ciph_ctx, ciph, NULL, NULL, NULL, send) <= 0
285 || !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
286 || (taglen != 0 && !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_TAG,
288 || EVP_CipherInit_ex(ciph_ctx, NULL, NULL, key, NULL, -1) <= 0) {
289 SSLerr(SSL_F_DERIVE_SECRET_KEY_AND_IV, ERR_R_EVP_LIB);
293 #ifdef OPENSSL_SSL_TRACE_CRYPTO
294 if (s->msg_callback) {
295 int wh = send ? TLS1_RT_CRYPTO_WRITE : 0;
298 s->msg_callback(2, s->version, wh | TLS1_RT_CRYPTO_KEY,
299 key, ciph->key_len, s, s->msg_callback_arg);
301 wh |= TLS1_RT_CRYPTO_IV;
302 s->msg_callback(2, s->version, wh, iv, ivlen, s,
303 s->msg_callback_arg);
309 OPENSSL_cleanse(key, sizeof(key));
313 int tls13_change_cipher_state(SSL *s, int which)
315 static const unsigned char client_handshake_traffic[] =
316 "client handshake traffic secret";
317 static const unsigned char client_application_traffic[] =
318 "client application traffic secret";
319 static const unsigned char server_handshake_traffic[] =
320 "server handshake traffic secret";
321 static const unsigned char server_application_traffic[] =
322 "server application traffic secret";
323 static const unsigned char resumption_master_secret[] =
324 "resumption master secret";
326 unsigned char secret[EVP_MAX_MD_SIZE];
327 unsigned char hashval[EVP_MAX_MD_SIZE];
328 unsigned char *hash = hashval;
329 unsigned char *insecret;
330 unsigned char *finsecret = NULL;
331 const char *log_label = NULL;
332 EVP_CIPHER_CTX *ciph_ctx;
333 size_t finsecretlen = 0;
334 const unsigned char *label;
335 size_t labellen, hashlen = 0;
338 if (which & SSL3_CC_READ) {
339 if (s->enc_read_ctx != NULL) {
340 EVP_CIPHER_CTX_reset(s->enc_read_ctx);
342 s->enc_read_ctx = EVP_CIPHER_CTX_new();
343 if (s->enc_read_ctx == NULL) {
344 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
348 ciph_ctx = s->enc_read_ctx;
351 RECORD_LAYER_reset_read_sequence(&s->rlayer);
353 if (s->enc_write_ctx != NULL) {
354 EVP_CIPHER_CTX_reset(s->enc_write_ctx);
356 s->enc_write_ctx = EVP_CIPHER_CTX_new();
357 if (s->enc_write_ctx == NULL) {
358 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
362 ciph_ctx = s->enc_write_ctx;
365 RECORD_LAYER_reset_write_sequence(&s->rlayer);
368 if (((which & SSL3_CC_CLIENT) && (which & SSL3_CC_WRITE))
369 || ((which & SSL3_CC_SERVER) && (which & SSL3_CC_READ))) {
370 if (which & SSL3_CC_HANDSHAKE) {
371 insecret = s->handshake_secret;
372 finsecret = s->client_finished_secret;
373 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
374 label = client_handshake_traffic;
375 labellen = sizeof(client_handshake_traffic) - 1;
376 log_label = CLIENT_HANDSHAKE_LABEL;
378 insecret = s->master_secret;
379 label = client_application_traffic;
380 labellen = sizeof(client_application_traffic) - 1;
381 log_label = CLIENT_APPLICATION_LABEL;
383 * For this we only use the handshake hashes up until the server
384 * Finished hash. We do not include the client's Finished, which is
385 * what ssl_handshake_hash() would give us. Instead we use the
386 * previously saved value.
388 hash = s->server_finished_hash;
391 if (which & SSL3_CC_HANDSHAKE) {
392 insecret = s->handshake_secret;
393 finsecret = s->server_finished_secret;
394 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
395 label = server_handshake_traffic;
396 labellen = sizeof(server_handshake_traffic) - 1;
397 log_label = SERVER_HANDSHAKE_LABEL;
399 insecret = s->master_secret;
400 label = server_application_traffic;
401 labellen = sizeof(server_application_traffic) - 1;
402 log_label = SERVER_APPLICATION_LABEL;
406 if (!ssl3_digest_cached_records(s, 1)
407 || !ssl_handshake_hash(s, hashval, sizeof(hashval), &hashlen)) {
408 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
413 * Save the hash of handshakes up to now for use when we calculate the
414 * client application traffic secret
416 if (label == server_application_traffic)
417 memcpy(s->server_finished_hash, hashval, hashlen);
419 if (label == client_application_traffic) {
421 * We also create the resumption master secret, but this time use the
422 * hash for the whole handshake including the Client Finished
424 if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
425 resumption_master_secret,
426 sizeof(resumption_master_secret) - 1,
427 hashval, s->session->master_key, hashlen)) {
428 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
431 s->session->master_key_length = hashlen;
434 if (!derive_secret_key_and_iv(s, which & SSL3_CC_WRITE, insecret, hash,
435 label, labellen, secret, iv, ciph_ctx)) {
439 if (label == server_application_traffic)
440 memcpy(s->server_app_traffic_secret, secret, hashlen);
441 else if (label == client_application_traffic)
442 memcpy(s->client_app_traffic_secret, secret, hashlen);
444 if (!ssl_log_secret(s, log_label, secret, hashlen)) {
445 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
449 if (finsecret != NULL
450 && !tls13_derive_finishedkey(s, ssl_handshake_md(s), secret,
451 finsecret, finsecretlen)) {
452 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
458 OPENSSL_cleanse(secret, sizeof(secret));
462 int tls13_update_key(SSL *s, int send)
464 static const unsigned char application_traffic[] =
465 "application traffic secret";
466 const EVP_MD *md = ssl_handshake_md(s);
467 size_t hashlen = EVP_MD_size(md);
468 unsigned char *insecret, *iv;
469 unsigned char secret[EVP_MAX_MD_SIZE];
470 EVP_CIPHER_CTX *ciph_ctx;
473 if (s->server == send)
474 insecret = s->server_app_traffic_secret;
476 insecret = s->client_app_traffic_secret;
480 ciph_ctx = s->enc_write_ctx;
481 RECORD_LAYER_reset_write_sequence(&s->rlayer);
484 ciph_ctx = s->enc_read_ctx;
485 RECORD_LAYER_reset_read_sequence(&s->rlayer);
488 if (!derive_secret_key_and_iv(s, send, insecret, NULL, application_traffic,
489 sizeof(application_traffic) - 1, secret, iv,
493 memcpy(insecret, secret, hashlen);
497 OPENSSL_cleanse(secret, sizeof(secret));
501 int tls13_alert_code(int code)
503 if (code == SSL_AD_MISSING_EXTENSION)
506 return tls1_alert_code(code);