From 0ca8d1ecf26b4a564222fc17e0e48053f2fd0843 Mon Sep 17 00:00:00 2001 From: Matt Caswell Date: Tue, 27 Jun 2017 14:57:15 +0100 Subject: [PATCH] Update SSL_export_keying_material() for TLSv1.3 Fixes #3680 Reviewed-by: Rich Salz (Merged from https://github.com/openssl/openssl/pull/3782) --- ssl/ssl_locl.h | 5 +++++ ssl/t1_lib.c | 2 +- ssl/tls13_enc.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 54 insertions(+), 1 deletion(-) diff --git a/ssl/ssl_locl.h b/ssl/ssl_locl.h index 7889ab5b0e..1105416d96 100644 --- a/ssl/ssl_locl.h +++ b/ssl/ssl_locl.h @@ -1073,6 +1073,7 @@ struct ssl_st { unsigned char handshake_traffic_hash[EVP_MAX_MD_SIZE]; unsigned char client_app_traffic_secret[EVP_MAX_MD_SIZE]; unsigned char server_app_traffic_secret[EVP_MAX_MD_SIZE]; + unsigned char exporter_master_secret[EVP_MAX_MD_SIZE]; EVP_CIPHER_CTX *enc_read_ctx; /* cryptographic state */ unsigned char read_iv[EVP_MAX_IV_LENGTH]; /* TLSv1.3 static read IV */ EVP_MD_CTX *read_hash; /* used for mac generation */ @@ -2288,6 +2289,10 @@ __owur int tls1_export_keying_material(SSL *s, unsigned char *out, size_t olen, const char *label, size_t llen, const unsigned char *p, size_t plen, int use_context); +__owur int tls13_export_keying_material(SSL *s, unsigned char *out, size_t olen, + const char *label, size_t llen, + const unsigned char *context, + size_t contextlen, int use_context); __owur int tls1_alert_code(int code); __owur int tls13_alert_code(int code); __owur int ssl3_alert_code(int code); diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index 4f28818c33..95b9b8b4d0 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -82,7 +82,7 @@ SSL3_ENC_METHOD const TLSv1_3_enc_data = { TLS_MD_CLIENT_FINISH_CONST, TLS_MD_CLIENT_FINISH_CONST_SIZE, TLS_MD_SERVER_FINISH_CONST, TLS_MD_SERVER_FINISH_CONST_SIZE, tls13_alert_code, - tls1_export_keying_material, + tls13_export_keying_material, SSL_ENC_FLAG_SIGALGS | SSL_ENC_FLAG_SHA256_PRF, ssl3_set_handshake_header, tls_close_construct_packet, diff --git a/ssl/tls13_enc.c b/ssl/tls13_enc.c index bc1995e21f..67ae0a3541 100644 --- a/ssl/tls13_enc.c +++ b/ssl/tls13_enc.c @@ -337,6 +337,7 @@ int tls13_change_cipher_state(SSL *s, int which) static const unsigned char client_application_traffic[] = "c ap traffic"; static const unsigned char server_handshake_traffic[] = "s hs traffic"; static const unsigned char server_application_traffic[] = "s ap traffic"; + static const unsigned char exporter_master_secret[] = "exp master"; static const unsigned char resumption_master_secret[] = "res master"; unsigned char *iv; unsigned char secret[EVP_MAX_MD_SIZE]; @@ -509,6 +510,15 @@ int tls13_change_cipher_state(SSL *s, int which) goto err; } s->session->master_key_length = hashlen; + + /* Now we create the exporter master secret */ + if (!tls13_hkdf_expand(s, ssl_handshake_md(s), insecret, + exporter_master_secret, + sizeof(exporter_master_secret) - 1, + hash, s->exporter_master_secret, hashlen)) { + SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR); + goto err; + } } if (!derive_secret_key_and_iv(s, which & SSL3_CC_WRITE, md, cipher, @@ -587,3 +597,41 @@ int tls13_alert_code(int code) return tls1_alert_code(code); } + +int tls13_export_keying_material(SSL *s, unsigned char *out, size_t olen, + const char *label, size_t llen, + const unsigned char *context, + size_t contextlen, int use_context) +{ + unsigned char exportsecret[EVP_MAX_MD_SIZE]; + static const unsigned char exporterlabel[] = "exporter"; + unsigned char hash[EVP_MAX_MD_SIZE]; + const EVP_MD *md = ssl_handshake_md(s); + EVP_MD_CTX *ctx = EVP_MD_CTX_new(); + unsigned int hashsize; + int ret = 0; + + if (ctx == NULL) + goto err; + + if (!SSL_is_init_finished(s)) + goto err; + + if (!use_context) + contextlen = 0; + + if (EVP_DigestInit_ex(ctx, md, NULL) <= 0 + || EVP_DigestUpdate(ctx, context, contextlen) <= 0 + || EVP_DigestFinal_ex(ctx, hash, &hashsize) <= 0 + || !tls13_hkdf_expand(s, md, s->exporter_master_secret, + (const unsigned char *)label, llen, NULL, + exportsecret, 0) + || !tls13_hkdf_expand(s, md, exportsecret, exporterlabel, + sizeof(exporterlabel) - 1, hash, out, olen)) + goto err; + + ret = 1; + err: + EVP_MD_CTX_free(ctx); + return ret; +} -- 2.25.1