ssl/tls13_enc.c

   1 /*
   2  * Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   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
   8  */
   9
  10 #include <stdlib.h>
  11 #include "ssl_locl.h"
  12 #include "internal/cryptlib.h"
  13 #include <openssl/evp.h>
  14 #include <openssl/kdf.h>
  15
  16 #define TLS13_MAX_LABEL_LEN     246
  17
  18 /* Always filled with zeros */
  19 static const unsigned char default_zeros[EVP_MAX_MD_SIZE];
  20
  21 /*
  22  * Given a |secret|; a |label| of length |labellen|; and |data| of length
  23  * |datalen| (e.g. typically a hash of the handshake messages), derive a new
  24  * secret |outlen| bytes long and store it in the location pointed to be |out|.
  25  * The |data| value may be zero length. Returns 1 on success  0 on failure.
  26  */
  27 int tls13_hkdf_expand(SSL *s, const EVP_MD *md, const unsigned char *secret,
  28                              const unsigned char *label, size_t labellen,
  29                              const unsigned char *data, size_t datalen,
  30                              unsigned char *out, size_t outlen)
  31 {
  32     const unsigned char label_prefix[] = "tls13 ";
  33     EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
  34     int ret;
  35     size_t hkdflabellen;
  36     size_t hashlen;
  37     /*
  38      * 2 bytes for length of whole HkdfLabel + 1 byte for length of combined
  39      * prefix and label + bytes for the label itself + bytes for the hash
  40      */
  41     unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t) +
  42                             + sizeof(label_prefix) + TLS13_MAX_LABEL_LEN
  43                             + EVP_MAX_MD_SIZE];
  44     WPACKET pkt;
  45
  46     if (pctx == NULL)
  47         return 0;
  48
  49     hashlen = EVP_MD_size(md);
  50
  51     if (!WPACKET_init_static_len(&pkt, hkdflabel, sizeof(hkdflabel), 0)
  52             || !WPACKET_put_bytes_u16(&pkt, outlen)
  53             || !WPACKET_start_sub_packet_u8(&pkt)
  54             || !WPACKET_memcpy(&pkt, label_prefix, sizeof(label_prefix) - 1)
  55             || !WPACKET_memcpy(&pkt, label, labellen)
  56             || !WPACKET_close(&pkt)
  57             || !WPACKET_sub_memcpy_u8(&pkt, data, (data == NULL) ? 0 : datalen)
  58             || !WPACKET_get_total_written(&pkt, &hkdflabellen)
  59             || !WPACKET_finish(&pkt)) {
  60         EVP_PKEY_CTX_free(pctx);
  61         WPACKET_cleanup(&pkt);
  62         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
  63                  ERR_R_INTERNAL_ERROR);
  64         return 0;
  65     }
  66
  67     ret = EVP_PKEY_derive_init(pctx) <= 0
  68             || EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY)
  69                <= 0
  70             || EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
  71             || EVP_PKEY_CTX_set1_hkdf_key(pctx, secret, hashlen) <= 0
  72             || EVP_PKEY_CTX_add1_hkdf_info(pctx, hkdflabel, hkdflabellen) <= 0
  73             || EVP_PKEY_derive(pctx, out, &outlen) <= 0;
  74
  75     EVP_PKEY_CTX_free(pctx);
  76
  77     if (ret != 0)
  78         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
  79                  ERR_R_INTERNAL_ERROR);
  80
  81     return ret == 0;
  82 }
  83
  84 /*
  85  * Given a |secret| generate a |key| of length |keylen| bytes. Returns 1 on
  86  * success  0 on failure.
  87  */
  88 int tls13_derive_key(SSL *s, const EVP_MD *md, const unsigned char *secret,
  89                      unsigned char *key, size_t keylen)
  90 {
  91     static const unsigned char keylabel[] = "key";
  92
  93     return tls13_hkdf_expand(s, md, secret, keylabel, sizeof(keylabel) - 1,
  94                              NULL, 0, key, keylen);
  95 }
  96
  97 /*
  98  * Given a |secret| generate an |iv| of length |ivlen| bytes. Returns 1 on
  99  * success  0 on failure.
 100  */
 101 int tls13_derive_iv(SSL *s, const EVP_MD *md, const unsigned char *secret,
 102                     unsigned char *iv, size_t ivlen)
 103 {
 104     static const unsigned char ivlabel[] = "iv";
 105
 106     return tls13_hkdf_expand(s, md, secret, ivlabel, sizeof(ivlabel) - 1,
 107                              NULL, 0, iv, ivlen);
 108 }
 109
 110 int tls13_derive_finishedkey(SSL *s, const EVP_MD *md,
 111                              const unsigned char *secret,
 112                              unsigned char *fin, size_t finlen)
 113 {
 114     static const unsigned char finishedlabel[] = "finished";
 115
 116     return tls13_hkdf_expand(s, md, secret, finishedlabel,
 117                              sizeof(finishedlabel) - 1, NULL, 0, fin, finlen);
 118 }
 119
 120 /*
 121  * Given the previous secret |prevsecret| and a new input secret |insecret| of
 122  * length |insecretlen|, generate a new secret and store it in the location
 123  * pointed to by |outsecret|. Returns 1 on success  0 on failure.
 124  */
 125 int tls13_generate_secret(SSL *s, const EVP_MD *md,
 126                           const unsigned char *prevsecret,
 127                           const unsigned char *insecret,
 128                           size_t insecretlen,
 129                           unsigned char *outsecret)
 130 {
 131     size_t mdlen, prevsecretlen;
 132     int ret;
 133     EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
 134     static const char derived_secret_label[] = "derived";
 135     unsigned char preextractsec[EVP_MAX_MD_SIZE];
 136
 137     if (pctx == NULL) {
 138         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_GENERATE_SECRET,
 139                  ERR_R_INTERNAL_ERROR);
 140         return 0;
 141     }
 142
 143     mdlen = EVP_MD_size(md);
 144
 145     if (insecret == NULL) {
 146         insecret = default_zeros;
 147         insecretlen = mdlen;
 148     }
 149     if (prevsecret == NULL) {
 150         prevsecret = default_zeros;
 151         prevsecretlen = 0;
 152     } else {
 153         EVP_MD_CTX *mctx = EVP_MD_CTX_new();
 154         unsigned char hash[EVP_MAX_MD_SIZE];
 155
 156         /* The pre-extract derive step uses a hash of no messages */
 157         if (mctx == NULL
 158                 || EVP_DigestInit_ex(mctx, md, NULL) <= 0
 159                 || EVP_DigestFinal_ex(mctx, hash, NULL) <= 0) {
 160             SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_GENERATE_SECRET,
 161                      ERR_R_INTERNAL_ERROR);
 162             EVP_MD_CTX_free(mctx);
 163             EVP_PKEY_CTX_free(pctx);
 164             return 0;
 165         }
 166         EVP_MD_CTX_free(mctx);
 167
 168         /* Generate the pre-extract secret */
 169         if (!tls13_hkdf_expand(s, md, prevsecret,
 170                                (unsigned char *)derived_secret_label,
 171                                sizeof(derived_secret_label) - 1, hash, mdlen,
 172                                preextractsec, mdlen)) {
 173             /* SSLfatal() already called */
 174             EVP_PKEY_CTX_free(pctx);
 175             return 0;
 176         }
 177
 178         prevsecret = preextractsec;
 179         prevsecretlen = mdlen;
 180     }
 181
 182     ret = EVP_PKEY_derive_init(pctx) <= 0
 183             || EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY)
 184                <= 0
 185             || EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
 186             || EVP_PKEY_CTX_set1_hkdf_key(pctx, insecret, insecretlen) <= 0
 187             || EVP_PKEY_CTX_set1_hkdf_salt(pctx, prevsecret, prevsecretlen)
 188                <= 0
 189             || EVP_PKEY_derive(pctx, outsecret, &mdlen)
 190                <= 0;
 191
 192     if (ret != 0)
 193         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_GENERATE_SECRET,
 194                  ERR_R_INTERNAL_ERROR);
 195
 196     EVP_PKEY_CTX_free(pctx);
 197     if (prevsecret == preextractsec)
 198         OPENSSL_cleanse(preextractsec, mdlen);
 199     return ret == 0;
 200 }
 201
 202 /*
 203  * Given an input secret |insecret| of length |insecretlen| generate the
 204  * handshake secret. This requires the early secret to already have been
 205  * generated. Returns 1 on success  0 on failure.
 206  */
 207 int tls13_generate_handshake_secret(SSL *s, const unsigned char *insecret,
 208                                 size_t insecretlen)
 209 {
 210     /* Calls SSLfatal() if required */
 211     return tls13_generate_secret(s, ssl_handshake_md(s), s->early_secret,
 212                                  insecret, insecretlen,
 213                                  (unsigned char *)&s->handshake_secret);
 214 }
 215
 216 /*
 217  * Given the handshake secret |prev| of length |prevlen| generate the master
 218  * secret and store its length in |*secret_size|. Returns 1 on success  0 on
 219  * failure.
 220  */
 221 int tls13_generate_master_secret(SSL *s, unsigned char *out,
 222                                  unsigned char *prev, size_t prevlen,
 223                                  size_t *secret_size)
 224 {
 225     const EVP_MD *md = ssl_handshake_md(s);
 226
 227     *secret_size = EVP_MD_size(md);
 228     /* Calls SSLfatal() if required */
 229     return tls13_generate_secret(s, md, prev, NULL, 0, out);
 230 }
 231
 232 /*
 233  * Generates the mac for the Finished message. Returns the length of the MAC or
 234  * 0 on error.
 235  */
 236 size_t tls13_final_finish_mac(SSL *s, const char *str, size_t slen,
 237                              unsigned char *out)
 238 {
 239     const EVP_MD *md = ssl_handshake_md(s);
 240     unsigned char hash[EVP_MAX_MD_SIZE];
 241     size_t hashlen, ret = 0;
 242     EVP_PKEY *key = NULL;
 243     EVP_MD_CTX *ctx = EVP_MD_CTX_new();
 244
 245     if (!ssl_handshake_hash(s, hash, sizeof(hash), &hashlen)) {
 246         /* SSLfatal() already called */
 247         goto err;
 248     }
 249
 250     if (str == s->method->ssl3_enc->server_finished_label)
 251         key = EVP_PKEY_new_raw_private_key(EVP_PKEY_HMAC, NULL,
 252                                            s->server_finished_secret, hashlen);
 253     else
 254         key = EVP_PKEY_new_raw_private_key(EVP_PKEY_HMAC, NULL,
 255                                            s->client_finished_secret, hashlen);
 256
 257     if (key == NULL
 258             || ctx == NULL
 259             || EVP_DigestSignInit(ctx, NULL, md, NULL, key) <= 0
 260             || EVP_DigestSignUpdate(ctx, hash, hashlen) <= 0
 261             || EVP_DigestSignFinal(ctx, out, &hashlen) <= 0) {
 262         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_FINAL_FINISH_MAC,
 263                  ERR_R_INTERNAL_ERROR);
 264         goto err;
 265     }
 266
 267     ret = hashlen;
 268  err:
 269     EVP_PKEY_free(key);
 270     EVP_MD_CTX_free(ctx);
 271     return ret;
 272 }
 273
 274 /*
 275  * There isn't really a key block in TLSv1.3, but we still need this function
 276  * for initialising the cipher and hash. Returns 1 on success or 0 on failure.
 277  */
 278 int tls13_setup_key_block(SSL *s)
 279 {
 280     const EVP_CIPHER *c;
 281     const EVP_MD *hash;
 282     int mac_type = NID_undef;
 283
 284     s->session->cipher = s->s3->tmp.new_cipher;
 285     if (!ssl_cipher_get_evp
 286         (s->session, &c, &hash, &mac_type, NULL, NULL, 0)) {
 287         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_SETUP_KEY_BLOCK,
 288                  SSL_R_CIPHER_OR_HASH_UNAVAILABLE);
 289         return 0;
 290     }
 291
 292     s->s3->tmp.new_sym_enc = c;
 293     s->s3->tmp.new_hash = hash;
 294
 295     return 1;
 296 }
 297
 298 static int derive_secret_key_and_iv(SSL *s, int sending, const EVP_MD *md,
 299                                     const EVP_CIPHER *ciph,
 300                                     const unsigned char *insecret,
 301                                     const unsigned char *hash,
 302                                     const unsigned char *label,
 303                                     size_t labellen, unsigned char *secret,
 304                                     unsigned char *iv, EVP_CIPHER_CTX *ciph_ctx)
 305 {
 306     unsigned char key[EVP_MAX_KEY_LENGTH];
 307     size_t ivlen, keylen, taglen;
 308     size_t hashlen = EVP_MD_size(md);
 309
 310     if (!tls13_hkdf_expand(s, md, insecret, label, labellen, hash, hashlen,
 311                            secret, hashlen)) {
 312         /* SSLfatal() already called */
 313         goto err;
 314     }
 315
 316     /* TODO(size_t): convert me */
 317     keylen = EVP_CIPHER_key_length(ciph);
 318     if (EVP_CIPHER_mode(ciph) == EVP_CIPH_CCM_MODE) {
 319         uint32_t algenc;
 320
 321         ivlen = EVP_CCM_TLS_IV_LEN;
 322         if (s->s3->tmp.new_cipher == NULL) {
 323             /* We've not selected a cipher yet - we must be doing early data */
 324             algenc = s->session->cipher->algorithm_enc;
 325         } else {
 326             algenc = s->s3->tmp.new_cipher->algorithm_enc;
 327         }
 328         if (algenc & (SSL_AES128CCM8 | SSL_AES256CCM8))
 329             taglen = EVP_CCM8_TLS_TAG_LEN;
 330          else
 331             taglen = EVP_CCM_TLS_TAG_LEN;
 332     } else {
 333         ivlen = EVP_CIPHER_iv_length(ciph);
 334         taglen = 0;
 335     }
 336
 337     if (!tls13_derive_key(s, md, secret, key, keylen)
 338             || !tls13_derive_iv(s, md, secret, iv, ivlen)) {
 339         /* SSLfatal() already called */
 340         goto err;
 341     }
 342
 343     if (EVP_CipherInit_ex(ciph_ctx, ciph, NULL, NULL, NULL, sending) <= 0
 344         || !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
 345         || (taglen != 0 && !EVP_CIPHER_CTX_ctrl(ciph_ctx, EVP_CTRL_AEAD_SET_TAG,
 346                                                 taglen, NULL))
 347         || EVP_CipherInit_ex(ciph_ctx, NULL, NULL, key, NULL, -1) <= 0) {
 348         SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_DERIVE_SECRET_KEY_AND_IV,
 349                  ERR_R_EVP_LIB);
 350         goto err;
 351     }
 352
 353     return 1;
 354  err:
 355     OPENSSL_cleanse(key, sizeof(key));
 356     return 0;
 357 }
 358
 359 int tls13_change_cipher_state(SSL *s, int which)
 360 {
 361     static const unsigned char client_early_traffic[] = "c e traffic";
 362     static const unsigned char client_handshake_traffic[] = "c hs traffic";
 363     static const unsigned char client_application_traffic[] = "c ap traffic";
 364     static const unsigned char server_handshake_traffic[] = "s hs traffic";
 365     static const unsigned char server_application_traffic[] = "s ap traffic";
 366     static const unsigned char exporter_master_secret[] = "exp master";
 367     static const unsigned char resumption_master_secret[] = "res master";
 368     static const unsigned char early_exporter_master_secret[] = "e exp master";
 369     unsigned char *iv;
 370     unsigned char secret[EVP_MAX_MD_SIZE];
 371     unsigned char hashval[EVP_MAX_MD_SIZE];
 372     unsigned char *hash = hashval;
 373     unsigned char *insecret;
 374     unsigned char *finsecret = NULL;
 375     const char *log_label = NULL;
 376     EVP_CIPHER_CTX *ciph_ctx;
 377     size_t finsecretlen = 0;
 378     const unsigned char *label;
 379     size_t labellen, hashlen = 0;
 380     int ret = 0;
 381     const EVP_MD *md = NULL;
 382     const EVP_CIPHER *cipher = NULL;
 383
 384     if (which & SSL3_CC_READ) {
 385         if (s->enc_read_ctx != NULL) {
 386             EVP_CIPHER_CTX_reset(s->enc_read_ctx);
 387         } else {
 388             s->enc_read_ctx = EVP_CIPHER_CTX_new();
 389             if (s->enc_read_ctx == NULL) {
 390                 SSLfatal(s, SSL_AD_INTERNAL_ERROR,
 391                          SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
 392                 goto err;
 393             }
 394         }
 395         ciph_ctx = s->enc_read_ctx;
 396         iv = s->read_iv;
 397
 398         RECORD_LAYER_reset_read_sequence(&s->rlayer);
 399     } else {
 400         s->statem.invalid_enc_write_ctx = 1;
 401         if (s->enc_write_ctx != NULL) {
 402             EVP_CIPHER_CTX_reset(s->enc_write_ctx);
 403         } else {
 404             s->enc_write_ctx = EVP_CIPHER_CTX_new();
 405             if (s->enc_write_ctx == NULL) {
 406                 SSLfatal(s, SSL_AD_INTERNAL_ERROR,
 407                          SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
 408                 goto err;
 409             }
 410             EVP_CIPHER_CTX_ctrl(s->enc_write_ctx, EVP_CTRL_SET_DRBG, 0, s->drbg);
 411         }
 412         ciph_ctx = s->enc_write_ctx;
 413         iv = s->write_iv;
 414
 415         RECORD_LAYER_reset_write_sequence(&s->rlayer);
 416     }
 417
 418     if (((which & SSL3_CC_CLIENT) && (which & SSL3_CC_WRITE))
 419             || ((which & SSL3_CC_SERVER) && (which & SSL3_CC_READ))) {
 420         if (which & SSL3_CC_EARLY) {
 421             EVP_MD_CTX *mdctx = NULL;
 422             long handlen;
 423             void *hdata;
 424             unsigned int hashlenui;
 425             const SSL_CIPHER *sslcipher = SSL_SESSION_get0_cipher(s->session);
 426
 427             insecret = s->early_secret;
 428             label = client_early_traffic;
 429             labellen = sizeof(client_early_traffic) - 1;
 430             log_label = CLIENT_EARLY_LABEL;
 431
 432             handlen = BIO_get_mem_data(s->s3->handshake_buffer, &hdata);
 433             if (handlen <= 0) {
 434                 SSLfatal(s, SSL_AD_INTERNAL_ERROR,
 435                          SSL_F_TLS13_CHANGE_CIPHER_STATE,
 436                          SSL_R_BAD_HANDSHAKE_LENGTH);
 437                 goto err;
 438             }
 439
 440             if (s->early_data_state == SSL_EARLY_DATA_CONNECTING
 441                     && s->max_early_data > 0
 442                     && s->session->ext.max_early_data == 0) {
 443                 /*
 444                  * If we are attempting to send early data, and we've decided to
 445                  * actually do it but max_early_data in s->session is 0 then we
 446                  * must be using an external PSK.
 447                  */
 448                 if (!ossl_assert(s->psksession != NULL
 449                         && s->max_early_data ==
 450                            s->psksession->ext.max_early_data)) {
 451                     SSLfatal(s, SSL_AD_INTERNAL_ERROR,
 452                              SSL_F_TLS13_CHANGE_CIPHER_STATE,
 453                              ERR_R_INTERNAL_ERROR);
 454                     goto err;
 455                 }
 456                 sslcipher = SSL_SESSION_get0_cipher(s->psksession);
 457             }
 458             if (sslcipher == NULL) {
 459                 SSLfatal(s, SSL_AD_INTERNAL_ERROR,
 460                          SSL_F_TLS13_CHANGE_CIPHER_STATE, SSL_R_BAD_PSK);
 461                 goto err;
 462             }
 463
 464             /*
 465              * We need to calculate the handshake digest using the digest from
 466              * the session. We haven't yet selected our ciphersuite so we can't
 467              * use ssl_handshake_md().
 468              */
 469             mdctx = EVP_MD_CTX_new();
 470             if (mdctx == NULL) {
 471                 SSLfatal(s, SSL_AD_INTERNAL_ERROR,
 472                          SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
 473                 goto err;
 474             }
 475             cipher = EVP_get_cipherbynid(SSL_CIPHER_get_cipher_nid(sslcipher));
 476             md = ssl_md(sslcipher->algorithm2);
 477             if (md == NULL || !EVP_DigestInit_ex(mdctx, md, NULL)
 478                     || !EVP_DigestUpdate(mdctx, hdata, handlen)
 479                     || !EVP_DigestFinal_ex(mdctx, hashval, &hashlenui)) {
 480                 SSLfatal(s, SSL_AD_INTERNAL_ERROR,
 481                          SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
 482                 EVP_MD_CTX_free(mdctx);
 483                 goto err;
 484             }
 485             hashlen = hashlenui;
 486             EVP_MD_CTX_free(mdctx);
 487
 488             if (!tls13_hkdf_expand(s, md, insecret,
 489                                    early_exporter_master_secret,
 490                                    sizeof(early_exporter_master_secret) - 1,
 491                                    hashval, hashlen,
 492                                    s->early_exporter_master_secret, hashlen)) {
 493                 SSLfatal(s, SSL_AD_INTERNAL_ERROR,
 494                          SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
 495                 goto err;
 496             }
 497         } else if (which & SSL3_CC_HANDSHAKE) {
 498             insecret = s->handshake_secret;
 499             finsecret = s->client_finished_secret;
 500             finsecretlen = EVP_MD_size(ssl_handshake_md(s));
 501             label = client_handshake_traffic;
 502             labellen = sizeof(client_handshake_traffic) - 1;
 503             log_label = CLIENT_HANDSHAKE_LABEL;
 504             /*
 505              * The handshake hash used for the server read/client write handshake
 506              * traffic secret is the same as the hash for the server
 507              * write/client read handshake traffic secret. However, if we
 508              * processed early data then we delay changing the server
 509              * read/client write cipher state until later, and the handshake
 510              * hashes have moved on. Therefore we use the value saved earlier
 511              * when we did the server write/client read change cipher state.
 512              */
 513             hash = s->handshake_traffic_hash;
 514         } else {
 515             insecret = s->master_secret;
 516             label = client_application_traffic;
 517             labellen = sizeof(client_application_traffic) - 1;
 518             log_label = CLIENT_APPLICATION_LABEL;
 519             /*
 520              * For this we only use the handshake hashes up until the server
 521              * Finished hash. We do not include the client's Finished, which is
 522              * what ssl_handshake_hash() would give us. Instead we use the
 523              * previously saved value.
 524              */
 525             hash = s->server_finished_hash;
 526         }
 527     } else {
 528         /* Early data never applies to client-read/server-write */
 529         if (which & SSL3_CC_HANDSHAKE) {
 530             insecret = s->handshake_secret;
 531             finsecret = s->server_finished_secret;
 532             finsecretlen = EVP_MD_size(ssl_handshake_md(s));
 533             label = server_handshake_traffic;
 534             labellen = sizeof(server_handshake_traffic) - 1;
 535             log_label = SERVER_HANDSHAKE_LABEL;
 536         } else {
 537             insecret = s->master_secret;
 538             label = server_application_traffic;
 539             labellen = sizeof(server_application_traffic) - 1;
 540             log_label = SERVER_APPLICATION_LABEL;
 541         }
 542     }
 543
 544     if (!(which & SSL3_CC_EARLY)) {
 545         md = ssl_handshake_md(s);
 546         cipher = s->s3->tmp.new_sym_enc;
 547         if (!ssl3_digest_cached_records(s, 1)
 548                 || !ssl_handshake_hash(s, hashval, sizeof(hashval), &hashlen)) {
 549             /* SSLfatal() already called */;
 550             goto err;
 551         }
 552     }
 553
 554     /*
 555      * Save the hash of handshakes up to now for use when we calculate the
 556      * client application traffic secret
 557      */
 558     if (label == server_application_traffic)
 559         memcpy(s->server_finished_hash, hashval, hashlen);
 560
 561     if (label == server_handshake_traffic)
 562         memcpy(s->handshake_traffic_hash, hashval, hashlen);
 563
 564     if (label == client_application_traffic) {
 565         /*
 566          * We also create the resumption master secret, but this time use the
 567          * hash for the whole handshake including the Client Finished
 568          */
 569         if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
 570                                resumption_master_secret,
 571                                sizeof(resumption_master_secret) - 1,
 572                                hashval, hashlen, s->session->master_key,
 573                                hashlen)) {
 574             /* SSLfatal() already called */
 575             goto err;
 576         }
 577         s->session->master_key_length = hashlen;
 578     }
 579
 580     if (!derive_secret_key_and_iv(s, which & SSL3_CC_WRITE, md, cipher,
 581                                   insecret, hash, label, labellen, secret, iv,
 582                                   ciph_ctx)) {
 583         /* SSLfatal() already called */
 584         goto err;
 585     }
 586
 587     if (label == server_application_traffic) {
 588         memcpy(s->server_app_traffic_secret, secret, hashlen);
 589         /* Now we create the exporter master secret */
 590         if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret,
 591                                exporter_master_secret,
 592                                sizeof(exporter_master_secret) - 1,
 593                                hash, hashlen, s->exporter_master_secret,
 594                                hashlen)) {
 595             /* SSLfatal() already called */
 596             goto err;
 597         }
 598     } else if (label == client_application_traffic)
 599         memcpy(s->client_app_traffic_secret, secret, hashlen);
 600
 601     if (!ssl_log_secret(s, log_label, secret, hashlen)) {
 602         /* SSLfatal() already called */
 603         goto err;
 604     }
 605
 606     if (finsecret != NULL
 607             && !tls13_derive_finishedkey(s, ssl_handshake_md(s), secret,
 608                                          finsecret, finsecretlen)) {
 609         /* SSLfatal() already called */
 610         goto err;
 611     }
 612
 613     s->statem.invalid_enc_write_ctx = 0;
 614     ret = 1;
 615  err:
 616     OPENSSL_cleanse(secret, sizeof(secret));
 617     return ret;
 618 }
 619
 620 int tls13_update_key(SSL *s, int sending)
 621 {
 622     static const unsigned char application_traffic[] = "traffic upd";
 623     const EVP_MD *md = ssl_handshake_md(s);
 624     size_t hashlen = EVP_MD_size(md);
 625     unsigned char *insecret, *iv;
 626     unsigned char secret[EVP_MAX_MD_SIZE];
 627     EVP_CIPHER_CTX *ciph_ctx;
 628     int ret = 0;
 629
 630     if (s->server == sending)
 631         insecret = s->server_app_traffic_secret;
 632     else
 633         insecret = s->client_app_traffic_secret;
 634
 635     if (sending) {
 636         s->statem.invalid_enc_write_ctx = 1;
 637         iv = s->write_iv;
 638         ciph_ctx = s->enc_write_ctx;
 639         RECORD_LAYER_reset_write_sequence(&s->rlayer);
 640     } else {
 641         iv = s->read_iv;
 642         ciph_ctx = s->enc_read_ctx;
 643         RECORD_LAYER_reset_read_sequence(&s->rlayer);
 644     }
 645
 646     if (!derive_secret_key_and_iv(s, sending, ssl_handshake_md(s),
 647                                   s->s3->tmp.new_sym_enc, insecret, NULL,
 648                                   application_traffic,
 649                                   sizeof(application_traffic) - 1, secret, iv,
 650                                   ciph_ctx)) {
 651         /* SSLfatal() already called */
 652         goto err;
 653     }
 654
 655     memcpy(insecret, secret, hashlen);
 656
 657     s->statem.invalid_enc_write_ctx = 0;
 658     ret = 1;
 659  err:
 660     OPENSSL_cleanse(secret, sizeof(secret));
 661     return ret;
 662 }
 663
 664 int tls13_alert_code(int code)
 665 {
 666     if (code == SSL_AD_MISSING_EXTENSION)
 667         return code;
 668
 669     return tls1_alert_code(code);
 670 }
 671
 672 int tls13_export_keying_material(SSL *s, unsigned char *out, size_t olen,
 673                                  const char *label, size_t llen,
 674                                  const unsigned char *context,
 675                                  size_t contextlen, int use_context)
 676 {
 677     unsigned char exportsecret[EVP_MAX_MD_SIZE];
 678     static const unsigned char exporterlabel[] = "exporter";
 679     unsigned char hash[EVP_MAX_MD_SIZE], data[EVP_MAX_MD_SIZE];
 680     const EVP_MD *md = ssl_handshake_md(s);
 681     EVP_MD_CTX *ctx = EVP_MD_CTX_new();
 682     unsigned int hashsize, datalen;
 683     int ret = 0;
 684
 685     if (ctx == NULL || !ossl_statem_export_allowed(s))
 686         goto err;
 687
 688     if (!use_context)
 689         contextlen = 0;
 690
 691     if (EVP_DigestInit_ex(ctx, md, NULL) <= 0
 692             || EVP_DigestUpdate(ctx, context, contextlen) <= 0
 693             || EVP_DigestFinal_ex(ctx, hash, &hashsize) <= 0
 694             || EVP_DigestInit_ex(ctx, md, NULL) <= 0
 695             || EVP_DigestFinal_ex(ctx, data, &datalen) <= 0
 696             || !tls13_hkdf_expand(s, md, s->exporter_master_secret,
 697                                   (const unsigned char *)label, llen,
 698                                   data, datalen, exportsecret, hashsize)
 699             || !tls13_hkdf_expand(s, md, exportsecret, exporterlabel,
 700                                   sizeof(exporterlabel) - 1, hash, hashsize,
 701                                   out, olen))
 702         goto err;
 703
 704     ret = 1;
 705  err:
 706     EVP_MD_CTX_free(ctx);
 707     return ret;
 708 }
 709
 710 int tls13_export_keying_material_early(SSL *s, unsigned char *out, size_t olen,
 711                                        const char *label, size_t llen,
 712                                        const unsigned char *context,
 713                                        size_t contextlen)
 714 {
 715     static const unsigned char exporterlabel[] = "exporter";
 716     unsigned char exportsecret[EVP_MAX_MD_SIZE];
 717     unsigned char hash[EVP_MAX_MD_SIZE], data[EVP_MAX_MD_SIZE];
 718     const EVP_MD *md;
 719     EVP_MD_CTX *ctx = EVP_MD_CTX_new();
 720     unsigned int hashsize, datalen;
 721     int ret = 0;
 722     const SSL_CIPHER *sslcipher;
 723
 724     if (ctx == NULL || !ossl_statem_export_early_allowed(s))
 725         goto err;
 726
 727     if (!s->server && s->max_early_data > 0
 728             && s->session->ext.max_early_data == 0)
 729         sslcipher = SSL_SESSION_get0_cipher(s->psksession);
 730     else
 731         sslcipher = SSL_SESSION_get0_cipher(s->session);
 732
 733     md = ssl_md(sslcipher->algorithm2);
 734
 735     /*
 736      * Calculate the hash value and store it in |data|. The reason why
 737      * the empty string is used is that the definition of TLS-Exporter
 738      * is like so:
 739      *
 740      * TLS-Exporter(label, context_value, key_length) =
 741      *     HKDF-Expand-Label(Derive-Secret(Secret, label, ""),
 742      *                       "exporter", Hash(context_value), key_length)
 743      *
 744      * Derive-Secret(Secret, Label, Messages) =
 745      *       HKDF-Expand-Label(Secret, Label,
 746      *                         Transcript-Hash(Messages), Hash.length)
 747      *
 748      * Here Transcript-Hash is the cipher suite hash algorithm.
 749      */
 750     if (EVP_DigestInit_ex(ctx, md, NULL) <= 0
 751             || EVP_DigestUpdate(ctx, context, contextlen) <= 0
 752             || EVP_DigestFinal_ex(ctx, hash, &hashsize) <= 0
 753             || EVP_DigestInit_ex(ctx, md, NULL) <= 0
 754             || EVP_DigestFinal_ex(ctx, data, &datalen) <= 0
 755             || !tls13_hkdf_expand(s, md, s->early_exporter_master_secret,
 756                                   (const unsigned char *)label, llen,
 757                                   data, datalen, exportsecret, hashsize)
 758             || !tls13_hkdf_expand(s, md, exportsecret, exporterlabel,
 759                                   sizeof(exporterlabel) - 1, hash, hashsize,
 760                                   out, olen))
 761         goto err;
 762
 763     ret = 1;
 764  err:
 765     EVP_MD_CTX_free(ctx);
 766     return ret;
 767 }