EAP-TTLS: Key derivation per draft-ietf-emu-tls-eap-types-00

Use the TLS-Exporter with the label and context as defined in
draft-ietf-emu-tls-eap-types-00 when deriving keys for EAP-TTLS with TLS
1.3.

Signed-off-by: Alexander Clouter <alex@digriz.org.uk>

src/eap_peer/eap_ttls.c

@@ -268,10 +268,22 @@ static int eap_ttls_avp_encapsulate(struct wpabuf **resp, u32 avp_code,
 static int eap_ttls_v0_derive_key(struct eap_sm *sm,
 				  struct eap_ttls_data *data)
 {
+	const char *label;
+	const u8 eap_tls13_context[1] = { EAP_TYPE_TTLS };
+	const u8 *context = NULL;
+	size_t context_len = 0;
+
+	if (data->ssl.tls_v13) {
+		label = "EXPORTER_EAP_TLS_Key_Material";
+		context = eap_tls13_context;
+		context_len = sizeof(eap_tls13_context);
+	} else {
+		label = "ttls keying material";
+	}
+
 	eap_ttls_free_key(data);
-	data->key_data = eap_peer_tls_derive_key(sm, &data->ssl,
-						 "ttls keying material",
-						 NULL, 0,
+	data->key_data = eap_peer_tls_derive_key(sm, &data->ssl, label,
+						 context, context_len,
 						 EAP_TLS_KEY_LEN +
 						 EAP_EMSK_LEN);
 	if (!data->key_data) {

src/eap_server/eap_server_ttls.c

@@ -1271,13 +1271,25 @@ static u8 * eap_ttls_getKey(struct eap_sm *sm, void *priv, size_t *len)
 {
 	struct eap_ttls_data *data = priv;
 	u8 *eapKeyData;
+	const char *label;
+	const u8 eap_tls13_context[1] = { EAP_TYPE_TTLS };
+	const u8 *context = NULL;
+	size_t context_len = 0;
 
 	if (data->state != SUCCESS)
 		return NULL;
 
+	if (data->ssl.tls_v13) {
+		label = "EXPORTER_EAP_TLS_Key_Material";
+		context = eap_tls13_context;
+		context_len = sizeof(eap_tls13_context);
+	} else {
+		label = "ttls keying material";
+	}
+
 	eapKeyData = eap_server_tls_derive_key(sm, &data->ssl,
-					       "ttls keying material", NULL, 0,
-					       EAP_TLS_KEY_LEN);
+					       label, context, context_len,
+					       EAP_TLS_KEY_LEN + EAP_EMSK_LEN);
 	if (eapKeyData) {
 		*len = EAP_TLS_KEY_LEN;
 		wpa_hexdump_key(MSG_DEBUG, "EAP-TTLS: Derived key",
@@ -1313,12 +1325,24 @@ static u8 * eap_ttls_get_emsk(struct eap_sm *sm, void *priv, size_t *len)
 {
 	struct eap_ttls_data *data = priv;
 	u8 *eapKeyData, *emsk;
+	const char *label;
+	const u8 eap_tls13_context[1] = { EAP_TYPE_TTLS };
+	const u8 *context = NULL;
+	size_t context_len = 0;
 
 	if (data->state != SUCCESS)
 		return NULL;
 
+	if (data->ssl.tls_v13) {
+		label = "EXPORTER_EAP_TLS_Key_Material";
+		context = eap_tls13_context;
+		context_len = sizeof(eap_tls13_context);
+	} else {
+		label = "ttls keying material";
+	}
+
 	eapKeyData = eap_server_tls_derive_key(sm, &data->ssl,
-					       "ttls keying material", NULL, 0,
+					       label, context, context_len,
 					       EAP_TLS_KEY_LEN + EAP_EMSK_LEN);
 	if (eapKeyData) {
 		emsk = os_malloc(EAP_EMSK_LEN);