Merge branch 'tmp-early-exporter' into 'master'

prf: add function to retrieve early keying material

Closes #736 and #329

See merge request gnutls/gnutls!894

29 files changed, 893 insertions, 165 deletions

diff --git a/.gitignore b/.gitignore
index 6716e4c728..f7983c159b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -369,6 +369,7 @@ tests/cve-2009-1415
 tests/cve-2009-1416
 tests/dane
 tests/dane-strcodes
+tests/datefudge-check
 tests/dh-params
 tests/dhepskself
 tests/dhex509self
@@ -830,6 +831,7 @@ tests/tls13/post-handshake-with-cert-ticket
 tests/tls13/post-handshake-with-psk
 tests/tls13/post-handshake-without-cert
 tests/tls13/prf
+tests/tls13/prf-early
 tests/tls13/psk-dumbfw
 tests/tls13/psk-ext
 tests/tls13/supported_versions
diff --git a/NEWS b/NEWS
index 0be3696576..0ada7c1a31 100644
--- a/NEWS
+++ b/NEWS
@@ -9,8 +9,10 @@ See the end for copying conditions.
 
 ** libgnutls: Added support for AES-XTS cipher (#354)
 
+** libgnutls: Added new function to retrieve early keying material (#329)
+
 ** API and ABI modifications:
-No changes since last version.
+gnutls_prf_early: Added
 
 
 * Version 3.6.7 (released 2019-03-27)
diff --git a/devel/libgnutls-latest-x86_64.abi b/devel/libgnutls-latest-x86_64.abi
index 9e23e0221c..c4659d954b 100644
--- a/devel/libgnutls-latest-x86_64.abi
+++ b/devel/libgnutls-latest-x86_64.abi
@@ -587,6 +587,7 @@
     <elf-symbol name='gnutls_pkcs_schema_get_name' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_pkcs_schema_get_oid' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_prf' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
+    <elf-symbol name='gnutls_prf_early' version='GNUTLS_3_6_6' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_prf_raw' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_prf_rfc5705' version='GNUTLS_3_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
     <elf-symbol name='gnutls_priority_certificate_type_list2' version='GNUTLS_3_6_4' is-default-version='yes' type='func-type' binding='global-binding' visibility='default-visibility' is-defined='yes'/>
diff --git a/devel/symbols.last b/devel/symbols.last
index e5f0e01c69..d9dedea09c 100644
--- a/devel/symbols.last
+++ b/devel/symbols.last
@@ -553,6 +553,7 @@ gnutls_pkcs8_info@GNUTLS_3_4
 gnutls_pkcs_schema_get_name@GNUTLS_3_4
 gnutls_pkcs_schema_get_oid@GNUTLS_3_4
 gnutls_prf@GNUTLS_3_4
+gnutls_prf_early@GNUTLS_3_6_6
 gnutls_prf_raw@GNUTLS_3_4
 gnutls_prf_rfc5705@GNUTLS_3_4
 gnutls_priority_certificate_type_list2@GNUTLS_3_6_4
diff --git a/doc/Makefile.am b/doc/Makefile.am
index 19982f5ad8..c60d0e46dd 100644
--- a/doc/Makefile.am
+++ b/doc/Makefile.am
@@ -1547,6 +1547,8 @@ FUNCS += functions/gnutls_pk_to_sign
 FUNCS += functions/gnutls_pk_to_sign.short
 FUNCS += functions/gnutls_prf
 FUNCS += functions/gnutls_prf.short
+FUNCS += functions/gnutls_prf_early
+FUNCS += functions/gnutls_prf_early.short
 FUNCS += functions/gnutls_prf_raw
 FUNCS += functions/gnutls_prf_raw.short
 FUNCS += functions/gnutls_prf_rfc5705
diff --git a/doc/manpages/Makefile.am b/doc/manpages/Makefile.am
index 0aab479df2..bbf4220c09 100644
--- a/doc/manpages/Makefile.am
+++ b/doc/manpages/Makefile.am
@@ -575,6 +575,7 @@ APIMANS += gnutls_pk_get_oid.3
 APIMANS += gnutls_pk_list.3
 APIMANS += gnutls_pk_to_sign.3
 APIMANS += gnutls_prf.3
+APIMANS += gnutls_prf_early.3
 APIMANS += gnutls_prf_raw.3
 APIMANS += gnutls_prf_rfc5705.3
 APIMANS += gnutls_priority_certificate_type_list.3
diff --git a/lib/ext/pre_shared_key.c b/lib/ext/pre_shared_key.c
index 771092fa9c..436a426a87 100644
--- a/lib/ext/pre_shared_key.c
+++ b/lib/ext/pre_shared_key.c
@@ -24,6 +24,7 @@
 #include "gnutls_int.h"
 #include "auth/psk.h"
 #include "handshake.h"
+#include "kx.h"
 #include "secrets.h"
 #include "tls13/anti_replay.h"
 #include "tls13/psk_ext_parser.h"
@@ -189,6 +190,70 @@ error:
 }
 
 static int
+generate_early_secrets(gnutls_session_t session,
+		       const mac_entry_st *prf)
+{
+	int ret;
+
+	ret = _tls13_derive_secret2(prf, EARLY_TRAFFIC_LABEL, sizeof(EARLY_TRAFFIC_LABEL)-1,
+				    session->internals.handshake_hash_buffer.data,
+				    session->internals.handshake_hash_buffer_client_hello_len,
+				    session->key.proto.tls13.temp_secret,
+				    session->key.proto.tls13.e_ckey);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	_gnutls_nss_keylog_write(session, "CLIENT_EARLY_TRAFFIC_SECRET",
+				 session->key.proto.tls13.e_ckey,
+				 prf->output_size);
+
+	ret = _tls13_derive_secret2(prf, EARLY_EXPORTER_MASTER_LABEL, sizeof(EARLY_EXPORTER_MASTER_LABEL)-1,
+				    session->internals.handshake_hash_buffer.data,
+				    session->internals.handshake_hash_buffer_client_hello_len,
+				    session->key.proto.tls13.temp_secret,
+				    session->key.proto.tls13.ap_expkey);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	_gnutls_nss_keylog_write(session, "EARLY_EXPORTER_SECRET",
+				 session->key.proto.tls13.ap_expkey,
+				 prf->output_size);
+
+	return 0;
+}
+
+/* Calculate TLS 1.3 Early Secret and the derived secrets from the
+ * selected PSK. */
+int
+_gnutls_generate_early_secrets_for_psk(gnutls_session_t session)
+{
+	const uint8_t *psk;
+	size_t psk_size;
+	const mac_entry_st *prf;
+	int ret;
+
+	psk = session->key.binders[0].psk.data;
+	psk_size = session->key.binders[0].psk.size;
+	prf = session->key.binders[0].prf;
+
+	if (unlikely(psk_size == 0))
+		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
+
+	ret = _tls13_init_secret2(prf, psk, psk_size,
+				  session->key.proto.tls13.temp_secret);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	session->key.proto.tls13.temp_secret_size = prf->output_size;
+
+	ret = generate_early_secrets(session, session->key.binders[0].prf);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	return 0;
+}
+
+static int
 client_send_params(gnutls_session_t session,
 		   gnutls_buffer_t extdata,
 		   const gnutls_psk_client_credentials_t cred)
@@ -651,6 +716,12 @@ static int server_recv_params(gnutls_session_t session,
 	session->key.binders[0].prf = prf;
 	session->key.binders[0].resumption = resuming;
 
+	ret = _gnutls_generate_early_secrets_for_psk(session);
+	if (ret < 0) {
+		gnutls_assert();
+		goto fail;
+	}
+
 	return 0;
 
  fail:
@@ -742,6 +813,7 @@ static int _gnutls_psk_recv_params(gnutls_session_t session,
 	unsigned i;
 	gnutls_psk_server_credentials_t pskcred;
 	const version_entry_st *vers = get_version(session);
+	int ret;
 
 	if (!vers || !vers->tls13_sem)
 		return 0;
@@ -759,9 +831,15 @@ static int _gnutls_psk_recv_params(gnutls_session_t session,
 						_gnutls_handshake_log("EXT[%p]: selected PSK mode\n", session);
 					}
 
-					/* ensure that selected binder is set on (our) index zero */
-					if (i != 0)
+					/* different PSK is selected, than the one we calculated early secrets */
+					if (i != 0) {
+						/* ensure that selected binder is set on (our) index zero */
 						swap_binders(session);
+
+						ret = _gnutls_generate_early_secrets_for_psk(session);
+						if (ret < 0)
+							return gnutls_assert_val(ret);
+					}
 					session->internals.hsk_flags |= HSK_PSK_SELECTED;
 				}
 			}
diff --git a/lib/ext/pre_shared_key.h b/lib/ext/pre_shared_key.h
index 4ad7b240f3..71116e5d10 100644
--- a/lib/ext/pre_shared_key.h
+++ b/lib/ext/pre_shared_key.h
@@ -18,4 +18,6 @@ unsigned _gnutls_have_psk_credentials(const gnutls_psk_client_credentials_t cred
 		return 0;
 }
 
+int _gnutls_generate_early_secrets_for_psk(gnutls_session_t session);
+
 #endif
diff --git a/lib/gnutls_int.h b/lib/gnutls_int.h
index 72d6c066b6..53ca32b19c 100644
--- a/lib/gnutls_int.h
+++ b/lib/gnutls_int.h
@@ -537,7 +537,7 @@ struct gnutls_key_st {
 			uint8_t hs_skey[MAX_HASH_SIZE]; /* server_hs_traffic_secret */
 			uint8_t ap_ckey[MAX_HASH_SIZE]; /* client_ap_traffic_secret */
 			uint8_t ap_skey[MAX_HASH_SIZE]; /* server_ap_traffic_secret */
-			uint8_t ap_expkey[MAX_HASH_SIZE]; /* exporter_master_secret */
+			uint8_t ap_expkey[MAX_HASH_SIZE]; /* {early_,}exporter_master_secret */
 			uint8_t ap_rms[MAX_HASH_SIZE]; /* resumption_master_secret */
 		} tls13; /* tls1.3 */
 
diff --git a/lib/handshake-defs.h b/lib/handshake-defs.h
index d322febc90..0b89cca608 100644
--- a/lib/handshake-defs.h
+++ b/lib/handshake-defs.h
@@ -34,7 +34,7 @@
 #define APPLICATION_TRAFFIC_UPDATE "traffic upd"
 #define EXPORTER_MASTER_LABEL "exp master"
 #define RMS_MASTER_LABEL "res master"
-#define EXPORTER_LABEL "exp master"
+#define EXPORTER_LABEL "exporter"
 #define RESUMPTION_LABEL "resumption"
 
 #define HRR_RANDOM \
diff --git a/lib/handshake.c b/lib/handshake.c
index 45bf99a6f7..1e6164cabe 100644
--- a/lib/handshake.c
+++ b/lib/handshake.c
@@ -45,6 +45,7 @@
 #include "constate.h"
 #include <record.h>
 #include <state.h>
+#include <ext/pre_shared_key.h>
 #include <ext/srp.h>
 #include <ext/session_ticket.h>
 #include <ext/status_request.h>
@@ -826,6 +827,14 @@ read_client_hello(gnutls_session_t session, uint8_t * data,
 		return ret;
 	}
 
+	/* Calculate TLS 1.3 Early Secret */
+	if (session->security_parameters.pversion->tls13_sem &&
+	    !(session->internals.hsk_flags & HSK_PSK_SELECTED)) {
+		ret = _tls13_init_secret(session, NULL, 0);
+		if (ret < 0)
+			return gnutls_assert_val(ret);
+	}
+
 	ret = set_auth_types(session);
 	if (ret < 0) {
 		gnutls_assert();
@@ -1265,7 +1274,7 @@ _gnutls_send_handshake2(gnutls_session_t session, mbuffer_st * bufel,
 
 	/* Here we keep the handshake messages in order to hash them...
 	 */
-	if (!IS_ASYNC(type, vers))
+	if (!IS_ASYNC(type, vers)) {
 		if ((ret =
 		     handshake_hash_add_sent(session, type, data,
 						     datasize)) < 0) {
@@ -1273,6 +1282,19 @@ _gnutls_send_handshake2(gnutls_session_t session, mbuffer_st * bufel,
 			_mbuffer_xfree(&bufel);
 			return ret;
 		}
+		/* If we are sending a PSK, generate early secrets here.
+		 * This cannot be done in pre_shared_key.c, because it
+		 * relies on transcript hash of a Client Hello. */
+		if (type == GNUTLS_HANDSHAKE_CLIENT_HELLO &&
+		    session->key.binders[0].prf != NULL) {
+			ret = _gnutls_generate_early_secrets_for_psk(session);
+			if (ret < 0) {
+				gnutls_assert();
+				_mbuffer_xfree(&bufel);
+				return ret;
+			}
+		}
+	}
 
 	ret = _gnutls_call_hook_func(session, type, GNUTLS_HOOK_PRE, 0,
 				     _mbuffer_get_udata_ptr(bufel), _mbuffer_get_udata_size(bufel));
@@ -1807,26 +1829,6 @@ no_resume:
 }
 
 
-static int generate_early_traffic_secret(gnutls_session_t session,
-					 const mac_entry_st *prf)
-{
-	int ret;
-
-	ret = _tls13_derive_secret2(prf, EARLY_TRAFFIC_LABEL, sizeof(EARLY_TRAFFIC_LABEL)-1,
-				    session->internals.handshake_hash_buffer.data,
-				    session->internals.handshake_hash_buffer_client_hello_len,
-				    session->key.proto.tls13.temp_secret,
-				    session->key.proto.tls13.e_ckey);
-	if (ret < 0)
-		return gnutls_assert_val(ret);
-
-	_gnutls_nss_keylog_write(session, "CLIENT_EARLY_TRAFFIC_SECRET",
-				 session->key.proto.tls13.e_ckey,
-				 prf->output_size);
-
-	return 0;
-}
-
 /* This function reads and parses the server hello handshake message.
  * This function also restores resumed parameters if we are resuming a
  * session.
@@ -1840,12 +1842,10 @@ read_server_hello(gnutls_session_t session,
 	uint8_t *cs_pos, *comp_pos, *srandom_pos;
 	uint8_t major, minor;
 	int pos = 0;
-	int ret = 0;
+	int ret;
 	int len = datalen;
 	unsigned ext_parse_flag = 0;
 	const version_entry_st *vers, *saved_vers;
-	const uint8_t *psk = NULL;
-	size_t psk_size = 0;
 
 	if (datalen < GNUTLS_RANDOM_SIZE+2) {
 		gnutls_assert();
@@ -1925,6 +1925,13 @@ read_server_hello(gnutls_session_t session,
 	if (ret < 0)
 		return gnutls_assert_val(ret);
 
+	/* reset keys and binders if we are not using TLS 1.3 */
+	if (!vers->tls13_sem) {
+		gnutls_memset(&session->key.proto.tls13, 0,
+			      sizeof(session->key.proto.tls13));
+		reset_binders(session);
+	}
+
 	/* check if we are resuming and set the appropriate
 	 * values;
 	 */
@@ -2016,31 +2023,17 @@ read_server_hello(gnutls_session_t session,
 
 	/* Calculate TLS 1.3 Early Secret */
 	if (vers->tls13_sem &&
-	    !(session->internals.hsk_flags & HSK_EARLY_DATA_IN_FLIGHT)) {
-		if (session->internals.hsk_flags & HSK_PSK_SELECTED) {
-			psk = session->key.binders[0].psk.data;
-			psk_size = session->key.binders[0].psk.size;
-
-			if (psk_size == 0)
-				return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_PARAMETER);
-		}
-
-		ret = _tls13_init_secret(session, psk, psk_size);
-		if (ret < 0) {
-			gnutls_assert();
-			return ret;
-		}
+	    !(session->internals.hsk_flags & HSK_PSK_SELECTED)) {
+		ret = _tls13_init_secret(session, NULL, 0);
+		if (ret < 0)
+			return gnutls_assert_val(ret);
 	}
 
 	ret = set_auth_types(session);
-	if (ret < 0) {
-		gnutls_assert();
-		goto cleanup;
-	}
-
-cleanup:
+	if (ret < 0)
+		return gnutls_assert_val(ret);
 
-	return ret;
+	return 0;
 }
 
 /* This function copies the appropriate compression methods, to a locally allocated buffer 
@@ -2064,56 +2057,6 @@ append_null_comp(gnutls_session_t session,
 	return ret;
 }
 
-/* Calculate TLS 1.3 Early Secret and client_early_traffic_secret,
- * assuming that the PSK we offer will be accepted by the server */
-static int
-generate_early_traffic_secret_from_ticket(gnutls_session_t session)
-{
-	int ret = 0;
-	const uint8_t *psk;
-	size_t psk_size;
-	const mac_entry_st *prf;
-
-	if (!(session->internals.hsk_flags & HSK_TLS13_TICKET_SENT)) {
-		ret = GNUTLS_E_INVALID_REQUEST;
-		gnutls_assert();
-		goto cleanup;
-	}
-
-	psk = session->key.binders[0].psk.data;
-	psk_size = session->key.binders[0].psk.size;
-	prf = session->key.binders[0].prf;
-
-	if (psk_size == 0) {
-		ret = GNUTLS_E_INVALID_REQUEST;
-		gnutls_assert();
-		goto cleanup;
-	}
-
-	ret = _tls13_init_secret2(prf, psk, psk_size,
-				  session->key.proto.tls13.temp_secret);
-	if (ret < 0) {
-		gnutls_assert();
-		goto cleanup;
-	}
-	session->key.proto.tls13.temp_secret_size = prf->output_size;
-
-	ret = generate_early_traffic_secret(session, prf);
-	if (ret < 0) {
-		gnutls_assert();
-		goto cleanup;
-	}
-
-	return ret;
-
- cleanup:
-	/* If any of the above calculation fails, we are not going to
-	 * send early data. */
-	session->internals.hsk_flags &= ~HSK_EARLY_DATA_IN_FLIGHT;
-
-	return ret;
-}
-
 /* This function sends the client hello handshake message.
  */
 static int send_client_hello(gnutls_session_t session, int again)
@@ -2349,9 +2292,6 @@ int _gnutls_send_server_hello(gnutls_session_t session, int again)
 	const version_entry_st *vers;
 	uint8_t vbytes[2];
 	unsigned extflag = 0;
-	const uint8_t *psk = NULL;
-	size_t psk_size = 0;
-	const mac_entry_st *prf = session->security_parameters.prf;
 	gnutls_ext_parse_type_t etype;
 
 	_gnutls_buffer_init(&buf);
@@ -2362,25 +2302,6 @@ int _gnutls_send_server_hello(gnutls_session_t session, int again)
 			return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
 
 		if (vers->tls13_sem) {
-			/* TLS 1.3 Early Secret */
-			if (session->internals.hsk_flags & HSK_PSK_SELECTED) {
-				psk = session->key.binders[0].psk.data;
-				psk_size = session->key.binders[0].psk.size;
-				prf = session->key.binders[0].prf;
-			}
-
-			ret = _tls13_init_secret(session, psk, psk_size);
-			if (ret < 0) {
-				gnutls_assert();
-				goto fail;
-			}
-
-			ret = generate_early_traffic_secret(session, prf);
-			if (ret < 0) {
-				gnutls_assert();
-				goto fail;
-			}
-
 			vbytes[0] = 0x03; /* TLS1.2 */
 			vbytes[1] = 0x03;
 			extflag |= GNUTLS_EXT_FLAG_TLS13_SERVER_HELLO;
@@ -2971,10 +2892,6 @@ static int handshake_client(gnutls_session_t session)
 		ret = send_client_hello(session, AGAIN(STATE1));
 		STATE = STATE1;
 		IMED_RET("send hello", ret, 1);
-		if (session->internals.hsk_flags & HSK_EARLY_DATA_IN_FLIGHT) {
-			ret = generate_early_traffic_secret_from_ticket(session);
-			IMED_RET_FATAL("generate early traffic keys from ticket", ret, 0);
-		}
 		FALLTHROUGH;
 	case STATE2:
 		if (IS_DTLS(session)) {
diff --git a/lib/includes/gnutls/gnutls.h.in b/lib/includes/gnutls/gnutls.h.in
index 7fc96aaea1..0801203128 100644
--- a/lib/includes/gnutls/gnutls.h.in
+++ b/lib/includes/gnutls/gnutls.h.in
@@ -1471,6 +1471,10 @@ int gnutls_prf_rfc5705(gnutls_session_t session,
 	       size_t label_size, const char *label,
 	       size_t context_size, const char *context,
 	       size_t outsize, char *out);
+int gnutls_prf_early(gnutls_session_t session,
+		     size_t label_size, const char *label,
+		     size_t context_size, const char *context,
+		     size_t outsize, char *out);
 
 int gnutls_prf_raw(gnutls_session_t session,
 		   size_t label_size, const char *label,
diff --git a/lib/libgnutls.map b/lib/libgnutls.map
index 19c9f535f9..d10e22b20e 100644
--- a/lib/libgnutls.map
+++ b/lib/libgnutls.map
@@ -1271,6 +1271,7 @@ GNUTLS_3_6_6
 	gnutls_certificate_set_rawpk_key_file;
 	gnutls_pcert_import_rawpk;
 	gnutls_pcert_import_rawpk_raw;
+	gnutls_prf_early;
 } GNUTLS_3_6_5;
 
 GNUTLS_FIPS140_3_4 {
diff --git a/lib/prf.c b/lib/prf.c
index dd66327e3d..6708b00db2 100644
--- a/lib/prf.c
+++ b/lib/prf.c
@@ -27,13 +27,12 @@
 
 #include "gnutls_int.h"
 #include "errors.h"
+#include "handshake.h"
 #include "secrets.h"
 #include <num.h>
 #include <state.h>
 #include <algorithms.h>
 
-#define EXPORTER_LABEL "exporter"
-
 /**
  * gnutls_prf_raw:
  * @session: is a #gnutls_session_t type.
@@ -90,6 +89,36 @@ gnutls_prf_raw(gnutls_session_t session,
 	return ret;
 }
 
+static int
+_tls13_derive_exporter(const mac_entry_st *prf,
+		       gnutls_session_t session,
+		       size_t label_size, const char *label,
+		       size_t context_size, const char *context,
+		       size_t outsize, char *out,
+		       bool early)
+{
+	uint8_t secret[MAX_HASH_SIZE];
+	uint8_t digest[MAX_HASH_SIZE];
+	unsigned digest_size = prf->output_size;
+	int ret;
+
+	ret = _tls13_derive_secret2(prf, label, label_size, NULL, 0,
+				    session->key.proto.tls13.ap_expkey,
+				    secret);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	ret = gnutls_hash_fast((gnutls_digest_algorithm_t)prf->id,
+			       context, context_size, digest);
+	if (ret < 0)
+		return gnutls_assert_val(ret);
+
+	return _tls13_expand_secret2(prf,
+				     EXPORTER_LABEL, sizeof(EXPORTER_LABEL)-1,
+				     digest, digest_size,
+				     secret, outsize, out);
+}
+
 /**
  * gnutls_prf_rfc5705:
  * @session: is a #gnutls_session_t type.
@@ -100,8 +129,8 @@ gnutls_prf_raw(gnutls_session_t session,
  * @outsize: size of pre-allocated output buffer to hold the output.
  * @out: pre-allocated buffer to hold the generated data.
  *
- * Exports keyring material from TLS/DTLS session to an application,
- * as specified in RFC5705.
+ * Exports keying material from TLS/DTLS session to an application, as
+ * specified in RFC5705.
  *
  * In the TLS versions prior to 1.3, it applies the TLS
  * Pseudo-Random-Function (PRF) on the master secret and the provided
@@ -137,30 +166,12 @@ gnutls_prf_rfc5705(gnutls_session_t session,
 	int ret;
 
 	if (vers && vers->tls13_sem) {
-		uint8_t secret[MAX_HASH_SIZE];
-		uint8_t digest[MAX_HASH_SIZE];
-		unsigned digest_size = session->security_parameters.prf->output_size;
-
-		/* exporter_master_secret might not be set, when
-		 * handshake is in progress */
-		if (session->internals.handshake_in_progress) {
-			gnutls_assert();
-			return GNUTLS_E_INVALID_REQUEST;
-		}
-
-		ret = _tls13_derive_secret(session, label, label_size, NULL, 0,
-					   session->key.proto.tls13.ap_expkey, secret);
-		if (ret < 0)
-			return gnutls_assert_val(ret);
-
-		ret = gnutls_hash_fast((gnutls_digest_algorithm_t)session->security_parameters.prf->id,
-				       context, context_size, digest);
-		if (ret < 0)
-			return gnutls_assert_val(ret);
-
-		ret = _tls13_expand_secret(session, EXPORTER_LABEL, sizeof(EXPORTER_LABEL)-1,
-					   digest, digest_size,
-					   secret, outsize, out);
+		ret = _tls13_derive_exporter(session->security_parameters.prf,
+					     session,
+					     label_size, label,
+					     context_size, context,
+					     outsize, out,
+					     0);
 	} else {
 		char *pctx = NULL;
 
@@ -191,6 +202,58 @@ gnutls_prf_rfc5705(gnutls_session_t session,
 }
 
 /**
+ * gnutls_prf_early:
+ * @session: is a #gnutls_session_t type.
+ * @label_size: length of the @label variable.
+ * @label: label used in PRF computation, typically a short string.
+ * @context_size: length of the @extra variable.
+ * @context: optional extra data to seed the PRF with.
+ * @outsize: size of pre-allocated output buffer to hold the output.
+ * @out: pre-allocated buffer to hold the generated data.
+ *
+ * This function is similar to gnutls_prf_rfc5705(), but only works in
+ * TLS 1.3 or later to export early keying material.
+ *
+ * Note that the keying material is only available after the
+ * ClientHello message is processed and before the application traffic
+ * keys are established.  Therefore this function shall be called in a
+ * handshake hook function for %GNUTLS_HANDSHAKE_CLIENT_HELLO.
+ *
+ * The @label variable usually contains a string denoting the purpose
+ * for the generated data.
+ *
+ * The @context variable can be used to add more data to the seed, after
+ * the random variables.  It can be used to make sure the
+ * generated output is strongly connected to some additional data
+ * (e.g., a string used in user authentication).
+ *
+ * The output is placed in @out, which must be pre-allocated.
+ *
+ * Note that, to provide the RFC5705 context, the @context variable
+ * must be non-null.
+ *
+ * Returns: %GNUTLS_E_SUCCESS on success, or an error code.
+ *
+ * Since: 3.6.6
+ **/
+int
+gnutls_prf_early(gnutls_session_t session,
+		 size_t label_size, const char *label,
+		 size_t context_size, const char *context,
+		 size_t outsize, char *out)
+{
+	if (session->internals.initial_negotiation_completed ||
+	    session->key.binders[0].prf == NULL)
+		return gnutls_assert_val(GNUTLS_E_INVALID_REQUEST);
+
+	return _tls13_derive_exporter(session->key.binders[0].prf, session,
+				      label_size, label,
+				      context_size, context,
+				      outsize, out,
+				      1);
+}
+
+/**
  * gnutls_prf:
  * @session: is a #gnutls_session_t type.
  * @label_size: length of the @label variable.
diff --git a/lib/state.c b/lib/state.c
index fe40bd980a..97461e6722 100644
--- a/lib/state.c
+++ b/lib/state.c
@@ -345,7 +345,7 @@ static void deinit_keys(gnutls_session_t session)
 	gnutls_pk_params_release(&session->key.kshare.ecdh_params);
 	gnutls_pk_params_release(&session->key.kshare.dh_params);
 
-	if (!vers->tls13_sem) {
+	if (!vers->tls13_sem && session->key.binders[0].prf == NULL) {
 		gnutls_pk_params_release(&session->key.proto.tls12.ecdh.params);
 		gnutls_pk_params_release(&session->key.proto.tls12.dh.params);
 		zrelease_temp_mpi_key(&session->key.proto.tls12.ecdh.x);
diff --git a/lib/tls13/session_ticket.c b/lib/tls13/session_ticket.c
index b8371c5005..146aee9b17 100644
--- a/lib/tls13/session_ticket.c
+++ b/lib/tls13/session_ticket.c
@@ -79,7 +79,7 @@ pack_ticket(gnutls_session_t session, tls13_ticket_st *ticket, gnutls_datum_t *p
 	memcpy(p, state.data, state.size);
 	p += state.size;
 
-	_gnutls_write_uint32(ticket->creation_time.tv_sec >> 32, p);
+	_gnutls_write_uint32((uint64_t) ticket->creation_time.tv_sec >> 32, p);
 	p += 4;
 	_gnutls_write_uint32(ticket->creation_time.tv_sec & 0xFFFFFFFF, p);
 	p += 4;
@@ -106,6 +106,7 @@ unpack_ticket(gnutls_session_t session, gnutls_datum_t *packed, tls13_ticket_st
 	const mac_entry_st *prf;
 	uint8_t *p;
 	ssize_t len;
+	uint64_t v;
 	int ret;
 
 	if (unlikely(packed == NULL || data == NULL))
@@ -168,10 +169,9 @@ unpack_ticket(gnutls_session_t session, gnutls_datum_t *packed, tls13_ticket_st
 	p += state.size;
 
 	DECR_LEN(len, 12);
-	creation_time.tv_sec = _gnutls_read_uint32(p);
+	v = _gnutls_read_uint32(p);
 	p += 4;
-	creation_time.tv_sec <<= 32;
-	creation_time.tv_sec |= _gnutls_read_uint32(p);
+	creation_time.tv_sec = (v << 32) | _gnutls_read_uint32(p);
 	p += 4;
 	creation_time.tv_nsec = _gnutls_read_uint32(p);
 
@@ -223,7 +223,11 @@ generate_session_ticket(gnutls_session_t session, tls13_ticket_st *ticket)
 
 	if ((ret = gnutls_rnd(GNUTLS_RND_NONCE, &ticket->age_add, sizeof(uint32_t))) < 0)
 		return gnutls_assert_val(ret);
-
+	/* This is merely to produce the same binder value on
+	 * different endian architectures. */
+#ifdef WORDS_BIGENDIAN
+	ticket->age_add = bswap_32(ticket->age_add);
+#endif
 
 	ticket->prf = session->security_parameters.prf;
 
diff --git a/src/cli-args.def b/src/cli-args.def
index 518a97466e..621de61f3c 100644
--- a/src/cli-args.def
+++ b/src/cli-args.def
@@ -423,6 +423,20 @@ flag = {
     doc       = "";
 };
 
+flag = {
+    name      = keymatexport;
+    arg-type  = string;
+    descrip   = "Label used for exporting keying material";
+    doc      = "";
+};
+
+flag = {
+    name      = keymatexportsize;
+    arg-type  = number;
+    descrip   = "Size of the exported keying material";
+    doc      = "";
+};
+
 doc-section = {
   ds-type   = 'SEE ALSO'; // or anything else
   ds-format = 'texi';      // or texi or mdoc format
diff --git a/src/cli.c b/src/cli.c
index a770c74bcc..691eb98c54 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -1659,6 +1659,11 @@ int do_handshake(socket_st * socket)
 	if (ret == 0) {
 		/* print some information */
 		print_info(socket->session, verbose, HAVE_OPT(X509CERTFILE)?P_WAIT_FOR_CERT:0);
+		if (HAVE_OPT(KEYMATEXPORT))
+			print_key_material(socket->session,
+					   OPT_ARG(KEYMATEXPORT),
+					   HAVE_OPT(KEYMATEXPORTSIZE) ?
+					   OPT_VALUE_KEYMATEXPORTSIZE : 20);
 		socket->secure = 1;
 	} else {
 		gnutls_alert_send_appropriate(socket->session, ret);
diff --git a/src/common.c b/src/common.c
index 28452fd589..664513c9ad 100644
--- a/src/common.c
+++ b/src/common.c
@@ -876,6 +876,43 @@ void print_list(const char *priorities, int verbose)
 	}
 }
 
+void
+print_key_material(gnutls_session_t session, const char *label, size_t size)
+{
+	gnutls_datum_t bin = { NULL, 0 }, hex = { NULL, 0 };
+	int ret;
+
+	bin.data = gnutls_malloc(size);
+	if (!bin.data) {
+		fprintf(stderr, "Error in gnutls_malloc: %s\n",
+			gnutls_strerror(GNUTLS_E_MEMORY_ERROR));
+		goto out;
+	}
+
+	bin.size = size;
+
+	ret = gnutls_prf_rfc5705(session, strlen(label), label,
+				 0, NULL, size, (char *)bin.data);
+	if (ret < 0) {
+		fprintf(stderr, "Error in gnutls_prf_rfc5705: %s\n",
+			gnutls_strerror(ret));
+		goto out;
+	}
+
+	ret = gnutls_hex_encode2(&bin, &hex);
+	if (ret < 0) {
+		fprintf(stderr, "Error in hex encoding: %s\n",
+			gnutls_strerror(ret));
+		goto out;
+	}
+	log_msg(stdout, "- Key material: %s\n", hex.data);
+	fflush(stdout);
+
+ out:
+	gnutls_free(bin.data);
+	gnutls_free(hex.data);
+}
+
 int check_command(gnutls_session_t session, const char *str, unsigned no_cli_cert)
 {
 	size_t len = strnlen(str, 128);
diff --git a/src/common.h b/src/common.h
index 588ee82bf1..91b9ed04f2 100644
--- a/src/common.h
+++ b/src/common.h
@@ -61,6 +61,7 @@ extern const char str_unknown[];
 #define P_WAIT_FOR_CERT (1<<1)
 int print_info(gnutls_session_t state, int verbose, int flags);
 void print_cert_info(gnutls_session_t, int flag, int print_cert);
+void print_key_material(gnutls_session_t, const char *label, size_t size);
 
 int log_msg(FILE *file, const char *message, ...) __attribute__((format(printf, 2, 3)));
 void log_set(FILE *file);
diff --git a/src/serv-args.def b/src/serv-args.def
index ac056f37dc..4be3d9f298 100644
--- a/src/serv-args.def
+++ b/src/serv-args.def
@@ -318,6 +318,20 @@ flag = {
     doc      = "This will override the default options in /etc/gnutls/pkcs11.conf";
 };
 
+flag = {
+    name      = keymatexport;
+    arg-type  = string;
+    descrip   = "Label used for exporting keying material";
+    doc      = "";
+};
+
+flag = {
+    name      = keymatexportsize;
+    arg-type  = number;
+    descrip   = "Size of the exported keying material";
+    doc      = "";
+};
+
 doc-section = {
   ds-type   = 'SEE ALSO'; // or anything else
   ds-format = 'texi';      // or texi or mdoc format
diff --git a/src/serv.c b/src/serv.c
index bc490ee7da..0866bff903 100644
--- a/src/serv.c
+++ b/src/serv.c
@@ -1331,6 +1331,13 @@ static void retry_handshake(listener_item *j)
 #endif
 
 			print_info(j->tls_session, verbose, verbose);
+
+			if (HAVE_OPT(KEYMATEXPORT))
+				print_key_material(j->tls_session,
+						   OPT_ARG(KEYMATEXPORT),
+						   HAVE_OPT(KEYMATEXPORTSIZE) ?
+						   OPT_VALUE_KEYMATEXPORTSIZE :
+						   20);
 		}
 
 		j->close_ok = 1;
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 96e10bfc5b..940e1ba605 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -104,7 +104,7 @@ noinst_LTLIBRARIES = libutils.la
 libutils_la_SOURCES = utils.h utils.c seccomp.c utils-adv.c
 libutils_la_LIBADD = ../lib/libgnutls.la
 
-indirect_tests =
+indirect_tests = tls13/prf-early
 ctests = tls13/supported_versions tls13/tls12-no-tls13-exts \
 	tls13/post-handshake-with-cert tls13/post-handshake-without-cert \
 	tls13/cookie tls13/key_share tls13/prf tls13/post-handshake-with-cert-ticket \
@@ -458,7 +458,7 @@ tls13_post_handshake_with_cert_pkcs11_LDADD = $(LDADD) $(LIBDL)
 endif
 endif
 
-dist_check_SCRIPTS = rfc2253-escape-test rsa-md5-collision/rsa-md5-collision.sh systemkey.sh
+dist_check_SCRIPTS = rfc2253-escape-test rsa-md5-collision/rsa-md5-collision.sh systemkey.sh tls13/prf-early.sh
 
 if !WINDOWS
 
@@ -527,6 +527,10 @@ sanity_cpp_CXXFLAGS = $(AM_CPPFLAGS) \
 endif
 endif
 
+if !WINDOWS
+indirect_tests += datefudge-check
+endif
+
 check_PROGRAMS = $(cpptests) $(ctests) $(indirect_tests)
 TESTS = $(cpptests) $(ctests) $(dist_check_SCRIPTS)
 
diff --git a/tests/datefudge-check.c b/tests/datefudge-check.c
new file mode 100644
index 0000000000..f2d896d622
--- /dev/null
+++ b/tests/datefudge-check.c
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2019 Red Hat
+ *
+ * Author: Daiki Ueno
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuTLS is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+int
+main (void)
+{
+	char outstr[200];
+	time_t t;
+	struct tm *tmp;
+
+	t = time(NULL);
+	tmp = localtime(&t);
+	if (tmp == NULL) {
+		perror("localtime");
+		exit(EXIT_FAILURE);
+	}
+
+	if (strftime(outstr, sizeof(outstr), "%s", tmp) == 0) {
+		fprintf(stderr, "strftime returned 0");
+		exit(EXIT_FAILURE);
+	}
+
+	puts(outstr);
+	exit(EXIT_SUCCESS);
+}
diff --git a/tests/scripts/common.sh b/tests/scripts/common.sh
index 1cce09d04e..d34915e1d7 100644
--- a/tests/scripts/common.sh
+++ b/tests/scripts/common.sh
@@ -76,7 +76,7 @@ check_for_datefudge() {
 		return
 	fi
 
-	TSTAMP=`datefudge -s "2006-09-23" date -u +%s || true`
+	TSTAMP=`datefudge -s "2006-09-23" "${top_builddir}/tests/datefudge-check" || true`
 	if test "$TSTAMP" != "1158969600" || test "$WINDOWS" = 1; then
 	echo $TSTAMP
 		echo "You need datefudge to run this test"
@@ -158,7 +158,7 @@ launch_server() {
 	shift
 
 	wait_for_free_port ${PORT}
-	${SERV} ${DEBUG} -p "${PORT}" $* >/dev/null &
+	${SERV} ${DEBUG} -p "${PORT}" $* >${LOGFILE-/dev/null} &
 }
 
 launch_pkcs11_server() {
@@ -177,7 +177,7 @@ launch_bare_server() {
 	shift
 
 	wait_for_free_port ${PORT}
-	${SERV} $* >/dev/null &
+	${SERV} $* >${LOGFILE-/dev/null} &
 }
 
 wait_server() {
diff --git a/tests/suite/testcompat-tls13-openssl.sh b/tests/suite/testcompat-tls13-openssl.sh
index 27ca3826e3..6d17941b8e 100755
--- a/tests/suite/testcompat-tls13-openssl.sh
+++ b/tests/suite/testcompat-tls13-openssl.sh
@@ -264,6 +264,28 @@ run_client_suite() {
 	kill ${PID}
 	wait
 
+	# Try exporting keying material
+	echo_cmd "${PREFIX}Checking TLS 1.3 to export keying material..."
+	testdir=`create_testdir tls13-openssl-keymatexport`
+	eval "${GETPORT}"
+	LOGFILE="${testdir}/server.out"
+	launch_bare_server $$ s_server -accept "${PORT}" -keyform pem -certform pem ${OPENSSL_DH_PARAMS_OPT} -key "${RSA_KEY}" -cert "${RSA_CERT}" -CAfile "${CA_CERT}" -keymatexport label -keymatexportlen 20
+	unset LOGFILE
+	PID=$!
+	wait_server ${PID}
+
+	${VALGRIND} "${CLI}" ${DEBUG} -p "${PORT}" 127.0.0.1 --priority "NORMAL:-VERS-ALL:+VERS-TLS1.3:+GROUP-ALL${ADD}" --keymatexport label --keymatexportsize 20| tee "${testdir}/client.out" >> ${OUTPUT}
+	grep '^- Key material: ' "${testdir}/client.out" | \
+	sed -e 's/^.*: //' -e 'y/abcdef/ABCDEF/' > "${testdir}/client.key" || \
+		fail ${PID} "Failed"
+	grep '^    Keying material: ' "${testdir}/server.out" | \
+	sed -e 's/^.*: //' -e 'y/abcdef/ABCDEF/' > "${testdir}/server.key" || \
+		fail ${PID} "Failed"
+	diff "${testdir}/client.key" "${testdir}/server.key" || \
+		fail ${PID} "Failed"
+	kill ${PID}
+	wait
+
 	rm -rf "${testdir}"
 
 }
diff --git a/tests/tls13/prf-early.c b/tests/tls13/prf-early.c
new file mode 100644
index 0000000000..758f78efe7
--- /dev/null
+++ b/tests/tls13/prf-early.c
@@ -0,0 +1,464 @@
+/*
+ * Copyright (C) 2015-2019 Red Hat, Inc.
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuTLS is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#if !defined(__linux__) || !defined(__GNUC__)
+
+int main(int argc, char **argv)
+{
+	exit(77);
+}
+
+#else
+
+#include <string.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <gnutls/gnutls.h>
+#include <gnutls/crypto.h>
+
+#include "cert-common.h"
+#include "utils.h"
+#include "virt-time.h"
+
+static void terminate(void);
+
+#define SESSIONS 2
+#define MAX_BUF 5*1024
+#define MSG "Hello TLS"
+
+/* This program tests whether the gnutls_prf() works as
+ * expected.
+ */
+
+static void server_log_func(int level, const char *str)
+{
+	fprintf(stderr, "server|<%d>| %s", level, str);
+}
+
+static void client_log_func(int level, const char *str)
+{
+	fprintf(stderr, "client|<%d>| %s", level, str);
+}
+
+/* These are global */
+static pid_t child;
+
+static const
+gnutls_datum_t hrnd = {(void*)"\x00\x02\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 32};
+static const
+gnutls_datum_t hsrnd = {(void*)"\x00\x05\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 32};
+
+static int gnutls_rnd_works;
+
+int __attribute__ ((visibility ("protected")))
+gnutls_rnd(gnutls_rnd_level_t level, void *data, size_t len)
+{
+	gnutls_rnd_works = 1;
+
+	memset(data, 0xff, len);
+
+	/* Flip the first byte to avoid infinite loop in the RSA
+	 * blinding code of Nettle */
+	if (len > 0)
+		memset(data, 0x0, 1);
+	return 0;
+}
+
+static gnutls_datum_t session_ticket_key = { NULL, 0 };
+
+static void dump(const char *name, const uint8_t *data, unsigned data_size)
+{
+	unsigned i;
+
+	fprintf(stderr, "%s", name);
+	for (i=0;i<data_size;i++)
+		fprintf(stderr, "\\x%.2x", (unsigned)data[i]);
+	fprintf(stderr, "\n");
+}
+
+#define TRY(label_size, label, extra_size, extra, size, exp) \
+	{ \
+	ret = gnutls_prf_early(session, label_size, label, extra_size, extra, size, \
+			 (void*)key_material); \
+	if (ret < 0) { \
+		fprintf(stderr, "gnutls_prf_early: error in %d\n", __LINE__); \
+		gnutls_perror(ret); \
+		exit(1); \
+	} \
+	if (memcmp(key_material, exp, size) != 0) { \
+		fprintf(stderr, "gnutls_prf_early: output doesn't match for '%s'\n", label); \
+		dump("got ", key_material, size); \
+		dump("expected ", exp, size); \
+		exit(1); \
+	} \
+	}
+
+#define KEY_EXP_VALUE "\xc0\x1e\xc2\xa4\xb7\xb4\x04\xaa\x91\x5d\xaf\xe8\xf7\x4d\x19\xdf\xd0\xe6\x08\xd6\xb4\x3b\xcf\xca\xc9\x32\x75\x3b\xe3\x11\x19\xb1\xac\x68"
+#define HELLO_VALUE "\x77\xdb\x10\x0b\xe8\xd0\xb9\x38\xbc\x49\xe6\xbe\xf2\x47\x2a\xcc\x6b\xea\xce\x85\x04\xd3\x9e\xd8\x06\x16\xad\xff\xcd\xbf\x4b"
+#define CONTEXT_VALUE "\xf2\x17\x9f\xf2\x66\x56\x87\x66\xf9\x5c\x8a\xd7\x4e\x1d\x46\xee\x0e\x44\x41\x4c\xcd\xac\xcb\xc0\x31\x41\x2a\xb6\xd7\x01\x62"
+#define NULL_CONTEXT_VALUE "\xcd\x79\x07\x93\xeb\x96\x07\x3e\xec\x78\x90\x89\xf7\x16\x42\x6d\x27\x87\x56\x7c\x7b\x60\x2b\x20\x44\xd1\xea\x0c\x89\xfb\x8b"
+
+static int handshake_callback_called;
+
+static int handshake_callback(gnutls_session_t session, unsigned int htype,
+			      unsigned post, unsigned int incoming, const gnutls_datum_t *msg)
+{
+	unsigned char key_material[512];
+	int ret;
+
+	assert(post == GNUTLS_HOOK_POST);
+
+	handshake_callback_called++;
+
+	TRY(13, "key expansion", 0, NULL, 34, (uint8_t*)KEY_EXP_VALUE);
+	TRY(6, "hello", 0, NULL, 31, (uint8_t*)HELLO_VALUE);
+	TRY(7, "context", 5, "abcd\xfa", 31, (uint8_t*)CONTEXT_VALUE);
+	TRY(12, "null-context", 0, "", 31, (uint8_t*)NULL_CONTEXT_VALUE);
+
+	return 0;
+}
+
+static void client(int sds[])
+{
+	gnutls_session_t session;
+	int ret, ii;
+	gnutls_certificate_credentials_t clientx509cred;
+	const char *err;
+	int t;
+	gnutls_datum_t session_data = {NULL, 0};
+	char buffer[MAX_BUF + 1];
+
+	global_init();
+
+	virt_time_init();
+
+	if (debug) {
+		gnutls_global_set_log_function(client_log_func);
+		gnutls_global_set_log_level(4711);
+	}
+
+	gnutls_certificate_allocate_credentials(&clientx509cred);
+
+	for (t = 0; t < SESSIONS; t++) {
+		/* Initialize TLS session
+		 */
+		gnutls_init(&session, GNUTLS_CLIENT);
+
+		/* Use default priorities */
+		ret = gnutls_priority_set_direct(session,
+						 "NONE:+VERS-TLS1.3:+AES-256-GCM:+AEAD:+SIGN-RSA-PSS-RSAE-SHA384:+GROUP-SECP256R1",
+						 &err);
+		if (ret < 0) {
+			fail("client: priority set failed (%s): %s\n",
+			     gnutls_strerror(ret), err);
+			exit(1);
+		}
+
+		ret = gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,
+					     clientx509cred);
+		if (ret < 0)
+			exit(1);
+
+		gnutls_handshake_set_random(session, &hrnd);
+		gnutls_transport_set_int(session, sds[t]);
+
+		if (t > 0) {
+			gnutls_session_set_data(session, session_data.data,
+						session_data.size);
+			gnutls_handshake_set_hook_function(session, GNUTLS_HANDSHAKE_CLIENT_HELLO,
+							   GNUTLS_HOOK_POST,
+							   handshake_callback);
+		}
+
+		/* Perform the TLS handshake
+		 */
+		do {
+			ret = gnutls_handshake(session);
+		}
+		while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
+
+		if (ret < 0) {
+			fail("client: Handshake failed: %s\n", strerror(ret));
+			exit(1);
+		} else {
+			if (debug)
+				success("client: Handshake was completed\n");
+		}
+
+		if (debug)
+			success("client: TLS version is: %s\n",
+				gnutls_protocol_get_name
+				(gnutls_protocol_get_version(session)));
+
+		ret = gnutls_cipher_get(session);
+		if (ret != GNUTLS_CIPHER_AES_256_GCM) {
+			fprintf(stderr, "negotiated unexpected cipher: %s\n", gnutls_cipher_get_name(ret));
+			exit(1);
+		}
+
+		ret = gnutls_mac_get(session);
+		if (ret != GNUTLS_MAC_AEAD) {
+			fprintf(stderr, "negotiated unexpected mac: %s\n", gnutls_mac_get_name(ret));
+			exit(1);
+		}
+
+		if (t == 0) {
+			/* get the session data size */
+			ret =
+			    gnutls_session_get_data2(session,
+						     &session_data);
+			if (ret < 0)
+				fail("Getting resume data failed\n");
+
+			if (handshake_callback_called != 0)
+				fail("client: handshake callback is called\n");
+		} else {
+			if (handshake_callback_called != t)
+				fail("client: handshake callback is not called\n");
+		}
+
+		gnutls_record_send(session, MSG, strlen(MSG));
+
+		do {
+			ret = gnutls_record_recv(session, buffer, MAX_BUF);
+		} while (ret == GNUTLS_E_AGAIN);
+		if (ret == 0) {
+			if (debug)
+				success
+				    ("client: Peer has closed the TLS connection\n");
+		} else if (ret < 0) {
+			fail("client: Error: %s\n", gnutls_strerror(ret));
+		}
+
+		if (debug) {
+			printf("- Received %d bytes: ", ret);
+			for (ii = 0; ii < ret; ii++) {
+				fputc(buffer[ii], stdout);
+			}
+			fputs("\n", stdout);
+		}
+
+		gnutls_bye(session, GNUTLS_SHUT_WR);
+
+		close(sds[t]);
+
+		gnutls_deinit(session);
+	}
+
+	gnutls_free(session_data.data);
+	gnutls_certificate_free_credentials(clientx509cred);
+
+	gnutls_global_deinit();
+}
+
+static void terminate(void)
+{
+	int status = 0;
+
+	kill(child, SIGTERM);
+	wait(&status);
+	exit(1);
+}
+
+static void server(int sds[])
+{
+	int ret;
+	gnutls_session_t session;
+	gnutls_certificate_credentials_t serverx509cred;
+	int t;
+	char buffer[MAX_BUF + 1];
+
+	/* this must be called once in the program
+	 */
+	global_init();
+
+	virt_time_init();
+
+	if (debug) {
+		gnutls_global_set_log_function(server_log_func);
+		gnutls_global_set_log_level(4711);
+	}
+
+	gnutls_certificate_allocate_credentials(&serverx509cred);
+
+	gnutls_session_ticket_key_generate(&session_ticket_key);
+
+	for (t = 0; t < SESSIONS; t++) {
+		gnutls_init(&session, GNUTLS_SERVER);
+
+		gnutls_session_ticket_enable_server(session,
+						    &session_ticket_key);
+
+		/* avoid calling all the priority functions, since the defaults
+		 * are adequate.
+		 */
+		ret = gnutls_priority_set_direct(session,
+						 "NORMAL:-VERS-ALL:+VERS-TLS1.3:-KX-ALL:-SIGN-ALL:+SIGN-RSA-PSS-RSAE-SHA384:-GROUP-ALL:+GROUP-SECP256R1", NULL);
+		if (ret < 0) {
+			fail("server: priority set failed (%s)\n\n",
+			     gnutls_strerror(ret));
+			terminate();
+		}
+
+		gnutls_certificate_set_x509_key_mem(serverx509cred,
+						    &server_cert, &server_key,
+						    GNUTLS_X509_FMT_PEM);
+		gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE,
+				       serverx509cred);
+
+		gnutls_handshake_set_random(session, &hsrnd);
+		gnutls_transport_set_int(session, sds[t]);
+
+		if (t > 0) {
+			if (!gnutls_rnd_works) {
+				fprintf(stderr, "gnutls_rnd() could not be overridden, skipping prf checks see #584\n");
+				exit(77);
+			} else {
+				gnutls_handshake_set_hook_function(session, GNUTLS_HANDSHAKE_CLIENT_HELLO,
+								   GNUTLS_HOOK_POST,
+								   handshake_callback);
+			}
+		}
+
+		do {
+			ret = gnutls_handshake(session);
+		}
+		while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
+		if (ret < 0) {
+			close(sds[t]);
+			gnutls_deinit(session);
+			fail("server: Handshake has failed (%s)\n\n",
+			     gnutls_strerror(ret));
+			terminate();
+		}
+		if (debug)
+			success("server: Handshake was completed\n");
+
+		if (debug)
+			success("server: TLS version is: %s\n",
+				gnutls_protocol_get_name
+				(gnutls_protocol_get_version(session)));
+
+		if (t == 0) {
+			if (handshake_callback_called != 0)
+				fail("server: handshake callback is called\n");
+		} else {
+			if (handshake_callback_called != t)
+				fail("server: handshake callback is not called\n");
+		}
+
+		for (;;) {
+			memset(buffer, 0, MAX_BUF + 1);
+			ret = gnutls_record_recv(session, buffer, MAX_BUF);
+
+			if (ret == 0) {
+				if (debug)
+					success
+					    ("server: Peer has closed the GnuTLS connection\n");
+				break;
+			} else if (ret < 0) {
+				kill(child, SIGTERM);
+				fail("server: Received corrupted data(%d). Closing...\n", ret);
+				break;
+			} else if (ret > 0) {
+				/* echo data back to the client
+				 */
+				gnutls_record_send(session, buffer,
+						   strlen(buffer));
+			}
+		}
+
+		/* do not wait for the peer to close the connection.
+		 */
+		gnutls_bye(session, GNUTLS_SHUT_WR);
+
+		close(sds[t]);
+		gnutls_deinit(session);
+	}
+
+	gnutls_certificate_free_credentials(serverx509cred);
+
+	gnutls_free(session_ticket_key.data);
+	session_ticket_key.data = NULL;
+
+	gnutls_global_deinit();
+
+	if (debug)
+		success("server: finished\n");
+}
+
+void doit(void)
+{
+	int client_sds[SESSIONS], server_sds[SESSIONS];
+	int i;
+	int ret;
+
+	signal(SIGPIPE, SIG_IGN);
+
+	for (i = 0; i < SESSIONS; i++) {
+		int sockets[2];
+
+		ret = socketpair(AF_UNIX, SOCK_STREAM, 0, sockets);
+		if (ret == -1) {
+			perror("socketpair");
+			fail("socketpair failed\n");
+			return;
+		}
+
+		server_sds[i] = sockets[0];
+		client_sds[i] = sockets[1];
+	}
+
+	child = fork();
+	if (child < 0) {
+		perror("fork");
+		fail("fork");
+		exit(1);
+	}
+
+	if (child) {
+		int status = 0;
+		/* parent */
+
+		for (i = 0; i < SESSIONS; i++)
+			close(client_sds[i]);
+		server(server_sds);
+		wait(&status);
+		check_wait_status(status);
+	} else {
+		for (i = 0; i < SESSIONS; i++)
+			close(server_sds[i]);
+		client(client_sds);
+		exit(0);
+	}
+}
+
+#endif				/* _WIN32 */
diff --git a/tests/tls13/prf-early.sh b/tests/tls13/prf-early.sh
new file mode 100755
index 0000000000..5b5ff0c33b
--- /dev/null
+++ b/tests/tls13/prf-early.sh
@@ -0,0 +1,29 @@
+#!/bin/sh
+
+# Copyright (C) 2019 Daiki Ueno
+#
+# This file is part of GnuTLS.
+#
+# GnuTLS is free software; you can redistribute it and/or modify it
+# under the terms of the GNU General Public License as published by the
+# Free Software Foundation; either version 3 of the License, or (at
+# your option) any later version.
+#
+# GnuTLS is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>
+#
+
+srcdir="${srcdir:-.}"
+builddir="${builddir:-.}"
+
+. "${srcdir}/scripts/common.sh"
+
+check_for_datefudge
+
+datefudge 2019-04-12 "${builddir}/tls13/prf-early" "$@"
+exit $?
diff --git a/tests/tls13/prf.c b/tests/tls13/prf.c
index 6cc96580dd..a8a529bcb8 100644
--- a/tests/tls13/prf.c
+++ b/tests/tls13/prf.c
@@ -314,6 +314,8 @@ static void server(int fd)
 			gnutls_protocol_get_name
 			(gnutls_protocol_get_version(session)));
 
+	check_prfs(session);
+
 	/* do not wait for the peer to close the connection.
 	 */
 	gnutls_bye(session, GNUTLS_SHUT_WR);