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 int tls13_change_cipher_state(SSL *s, int which)
247 static const unsigned char client_handshake_traffic[] =
248 "client handshake traffic secret";
249 static const unsigned char client_application_traffic[] =
250 "client application traffic secret";
251 static const unsigned char server_handshake_traffic[] =
252 "server handshake traffic secret";
253 static const unsigned char server_application_traffic[] =
254 "server application traffic secret";
255 static const unsigned char resumption_master_secret[] =
256 "resumption master secret";
257 unsigned char key[EVP_MAX_KEY_LENGTH];
259 unsigned char secret[EVP_MAX_MD_SIZE];
260 unsigned char hashval[EVP_MAX_MD_SIZE];
261 unsigned char *hash = hashval;
262 unsigned char *insecret;
263 unsigned char *finsecret = NULL;
264 EVP_CIPHER_CTX *ciph_ctx;
265 const EVP_CIPHER *ciph = s->s3->tmp.new_sym_enc;
266 size_t ivlen, keylen, finsecretlen = 0;
267 const unsigned char *label;
268 size_t labellen, hashlen = 0;
271 if (which & SSL3_CC_READ) {
272 if (s->enc_read_ctx != NULL) {
273 EVP_CIPHER_CTX_reset(s->enc_read_ctx);
275 s->enc_read_ctx = EVP_CIPHER_CTX_new();
276 if (s->enc_read_ctx == NULL) {
277 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
281 ciph_ctx = s->enc_read_ctx;
284 RECORD_LAYER_reset_read_sequence(&s->rlayer);
286 if (s->enc_write_ctx != NULL) {
287 EVP_CIPHER_CTX_reset(s->enc_write_ctx);
289 s->enc_write_ctx = EVP_CIPHER_CTX_new();
290 if (s->enc_write_ctx == NULL) {
291 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
295 ciph_ctx = s->enc_write_ctx;
298 RECORD_LAYER_reset_write_sequence(&s->rlayer);
301 if (((which & SSL3_CC_CLIENT) && (which & SSL3_CC_WRITE))
302 || ((which & SSL3_CC_SERVER) && (which & SSL3_CC_READ))) {
303 if (which & SSL3_CC_HANDSHAKE) {
304 insecret = s->handshake_secret;
305 finsecret = s->client_finished_secret;
306 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
307 label = client_handshake_traffic;
308 labellen = sizeof(client_handshake_traffic) - 1;
310 insecret = s->master_secret;
311 label = client_application_traffic;
312 labellen = sizeof(client_application_traffic) - 1;
314 * For this we only use the handshake hashes up until the server
315 * Finished hash. We do not include the client's Finished, which is
316 * what ssl_handshake_hash() would give us. Instead we use the
317 * previously saved value.
319 hash = s->server_finished_hash;
322 if (which & SSL3_CC_HANDSHAKE) {
323 insecret = s->handshake_secret;
324 finsecret = s->server_finished_secret;
325 finsecretlen = EVP_MD_size(ssl_handshake_md(s));
326 label = server_handshake_traffic;
327 labellen = sizeof(server_handshake_traffic) - 1;
329 insecret = s->master_secret;
330 label = server_application_traffic;
331 labellen = sizeof(server_application_traffic) - 1;
335 if (!ssl3_digest_cached_records(s, 1)
336 || !ssl_handshake_hash(s, hashval, sizeof(hashval), &hashlen)) {
337 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
342 * Save the hash of handshakes up to now for use when we calculate the
343 * client application traffic secret
345 if (label == server_application_traffic)
346 memcpy(s->server_finished_hash, hashval, hashlen);
348 if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret, label, labellen,
349 hash, secret, hashlen)) {
350 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
354 if (label == client_application_traffic) {
356 * We also create the resumption master secret, but this time use the
357 * hash for the whole handshake including the Client Finished
359 if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
360 resumption_master_secret,
361 sizeof(resumption_master_secret) - 1,
362 hashval, s->session->master_key, hashlen)) {
363 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
366 s->session->master_key_length = hashlen;
369 /* TODO(size_t): convert me */
370 keylen = EVP_CIPHER_key_length(ciph);
371 ivlen = EVP_CIPHER_iv_length(ciph);
373 if (!tls13_derive_key(s, secret, key, keylen)
374 || !tls13_derive_iv(s, secret, iv, ivlen)
375 || (finsecret != NULL && !tls13_derive_finishedkey(s,
380 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
384 if (EVP_CipherInit_ex(ciph_ctx, ciph, NULL, key, NULL,
385 (which & SSL3_CC_WRITE)) <= 0) {
386 SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_EVP_LIB);
390 #ifdef OPENSSL_SSL_TRACE_CRYPTO
391 if (s->msg_callback) {
392 int wh = which & SSL3_CC_WRITE ? TLS1_RT_CRYPTO_WRITE : 0;
395 s->msg_callback(2, s->version, wh | TLS1_RT_CRYPTO_KEY,
396 key, ciph->key_len, s, s->msg_callback_arg);
398 wh |= TLS1_RT_CRYPTO_IV;
399 s->msg_callback(2, s->version, wh, iv, ivlen, s,
400 s->msg_callback_arg);
406 OPENSSL_cleanse(secret, sizeof(secret));
407 OPENSSL_cleanse(key, sizeof(key));
411 int tls13_alert_code(int code)
413 if (code == SSL_AD_MISSING_EXTENSION)
416 return tls1_alert_code(code);