DPP: Use Transaction ID in Peer Discovery Request/Response frames

DPP tech spec changed the contents of these frames by replacing the
public key hash attributes with a Transaction ID attribute that gets
copied from the request to the response to identify the transaction in a
simpler manner.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

src/ap/dpp_hostapd.c

@@ -895,8 +895,8 @@ static void hostapd_dpp_rx_peer_disc_req(struct hostapd_data *hapd,
 					 const u8 *buf, size_t len,
 					 unsigned int freq)
 {
-	const u8 *connector;
+	const u8 *connector, *trans_id;
-	u16 connector_len;
+	u16 connector_len, trans_id_len;
 	struct os_time now;
 	struct dpp_introduction intro;
 	os_time_t expire;
@@ -931,6 +931,14 @@ static void hostapd_dpp_rx_peer_disc_req(struct hostapd_data *hapd,
 		return;
 	}
 
+	trans_id = dpp_get_attr(buf, len, DPP_ATTR_TRANSACTION_ID,
+			       &trans_id_len);
+	if (!trans_id || trans_id_len != 1) {
+		wpa_printf(MSG_DEBUG,
+			   "DPP: Peer did not include Transaction ID");
+		return;
+	}
+
 	connector = dpp_get_attr(buf, len, DPP_ATTR_CONNECTOR, &connector_len);
 	if (!connector) {
 		wpa_printf(MSG_DEBUG,
@@ -966,20 +974,14 @@ static void hostapd_dpp_rx_peer_disc_req(struct hostapd_data *hapd,
 	}
 
 	msg = dpp_alloc_msg(DPP_PA_PEER_DISCOVERY_RESP,
-			    2 * (4 + SHA256_MAC_LEN) +
+			    5 + 4 + os_strlen(hapd->conf->dpp_connector));
-			    4 + os_strlen(hapd->conf->dpp_connector));
 	if (!msg)
 		return;
 
-	/* SHA256(PK) */
+	/* Transaction ID */
-	wpabuf_put_le16(msg, DPP_ATTR_PEER_NET_PK_HASH);
+	wpabuf_put_le16(msg, DPP_ATTR_TRANSACTION_ID);
-	wpabuf_put_le16(msg, SHA256_MAC_LEN);
+	wpabuf_put_le16(msg, 1);
-	wpabuf_put_data(msg, intro.pk_hash, SHA256_MAC_LEN);
+	wpabuf_put_u8(msg, trans_id[0]);
-
-	/* SHA256(NK) */
-	wpabuf_put_le16(msg, DPP_ATTR_OWN_NET_NK_HASH);
-	wpabuf_put_le16(msg, SHA256_MAC_LEN);
-	wpabuf_put_data(msg, intro.nk_hash, SHA256_MAC_LEN);
 
 	/* DPP Connector */
 	wpabuf_put_le16(msg, DPP_ATTR_CONNECTOR);

src/common/dpp.c

@@ -4577,30 +4577,6 @@ fail:
 }
 
 
-static int dpp_netkey_hash(EVP_PKEY *key, u8 *hash)
-{
-	EC_KEY *eckey;
-	unsigned char *der = NULL;
-	int ret, der_len;
-	const u8 *addr[1];
-	size_t len[1];
-
-	eckey = EVP_PKEY_get1_EC_KEY(key);
-	if (!eckey)
-		return -1;
-	EC_KEY_set_conv_form(eckey, POINT_CONVERSION_COMPRESSED);
-	der_len = i2d_EC_PUBKEY(eckey, &der);
-	EC_KEY_free(eckey);
-	if (der_len <= 0)
-		return -1;
-	addr[0] = der;
-	len[0] = der_len;
-	ret = sha256_vector(1, addr, len, hash);
-	OPENSSL_free(der);
-	return ret;
-}
-
-
 int dpp_peer_intro(struct dpp_introduction *intro, const char *own_connector,
 		   const u8 *net_access_key, size_t net_access_key_len,
 		   const u8 *csign_key, size_t csign_key_len,
@@ -4753,12 +4729,6 @@ int dpp_peer_intro(struct dpp_introduction *intro, const char *own_connector,
 		goto fail;
 	}
 
-	if (dpp_netkey_hash(own_key, intro->nk_hash) < 0 ||
-	    dpp_netkey_hash(peer_key, intro->pk_hash) < 0) {
-		wpa_printf(MSG_ERROR, "DPP: Failed to derive NK/PK hash");
-		goto fail;
-	}
-
 	ret = 0;
 fail:
 	if (ret < 0)

src/common/dpp.h

@@ -44,12 +44,12 @@ enum dpp_attribute_id {
 	DPP_ATTR_CONNECTOR = 0x100D,
 	DPP_ATTR_CONFIG_ATTR_OBJ = 0x100E,
 	DPP_ATTR_BOOTSTRAP_KEY = 0x100F,
-	DPP_ATTR_PEER_NET_PK_HASH = 0x1010,
 	DPP_ATTR_OWN_NET_NK_HASH = 0x1011,
 	DPP_ATTR_FINITE_CYCLIC_GROUP = 0x1012,
 	DPP_ATTR_ENCRYPTED_KEY = 0x1013,
 	DPP_ATTR_ENROLLEE_NONCE = 0x1014,
 	DPP_ATTR_CODE_IDENTIFIER = 0x1015,
+	DPP_ATTR_TRANSACTION_ID = 0x1016,
 };
 
 enum dpp_status_error {
@@ -201,8 +201,6 @@ struct dpp_introduction {
 	u8 pmkid[PMKID_LEN];
 	u8 pmk[PMK_LEN_MAX];
 	size_t pmk_len;
-	u8 pk_hash[SHA256_MAC_LEN];
-	u8 nk_hash[SHA256_MAC_LEN];
 };
 
 void dpp_bootstrap_info_free(struct dpp_bootstrap_info *info);

wpa_supplicant/dpp_supplicant.c

@@ -38,6 +38,10 @@ static void wpas_dpp_tx_status(struct wpa_supplicant *wpa_s,
 
 static const u8 broadcast[ETH_ALEN] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 
+/* Use a hardcoded Transaction ID 1 in Peer Discovery frames since there is only
+ * a single transaction in progress at any point in time. */
+static const u8 TRANSACTION_ID = 1;
+
 
 static struct dpp_configurator *
 dpp_configurator_get_id(struct wpa_supplicant *wpa_s, unsigned int id)
@@ -1256,8 +1260,8 @@ static void wpas_dpp_rx_peer_disc_resp(struct wpa_supplicant *wpa_s,
 				       const u8 *buf, size_t len)
 {
 	struct wpa_ssid *ssid;
-	const u8 *connector, *pk_hash, *nk_hash;
+	const u8 *connector, *trans_id;
-	u16 connector_len, pk_hash_len, nk_hash_len;
+	u16 connector_len, trans_id_len;
 	struct dpp_introduction intro;
 	struct rsn_pmksa_cache_entry *entry;
 	struct os_time now;
@@ -1286,6 +1290,20 @@ static void wpas_dpp_rx_peer_disc_resp(struct wpa_supplicant *wpa_s,
 		return;
 	}
 
+	trans_id = dpp_get_attr(buf, len, DPP_ATTR_TRANSACTION_ID,
+			       &trans_id_len);
+	if (!trans_id || trans_id_len != 1) {
+		wpa_printf(MSG_DEBUG,
+			   "DPP: Peer did not include Transaction ID");
+		goto fail;
+	}
+	if (trans_id[0] != TRANSACTION_ID) {
+		wpa_printf(MSG_DEBUG,
+			   "DPP: Ignore frame with unexpected Transaction ID %u",
+			   trans_id[0]);
+		goto fail;
+	}
+
 	connector = dpp_get_attr(buf, len, DPP_ATTR_CONNECTOR, &connector_len);
 	if (!connector) {
 		wpa_printf(MSG_DEBUG,
@@ -1304,36 +1322,6 @@ static void wpas_dpp_rx_peer_disc_resp(struct wpa_supplicant *wpa_s,
 		goto fail;
 	}
 
-	pk_hash = dpp_get_attr(buf, len, DPP_ATTR_PEER_NET_PK_HASH,
-			       &pk_hash_len);
-	if (!pk_hash || pk_hash_len != SHA256_MAC_LEN) {
-		wpa_printf(MSG_DEBUG, "DPP: Peer did not include SHA256(PK)");
-		goto fail;
-	}
-	if (os_memcmp(pk_hash, intro.nk_hash, SHA256_MAC_LEN) != 0) {
-		wpa_printf(MSG_DEBUG, "DPP: SHA256(PK) mismatch");
-		wpa_hexdump(MSG_DEBUG, "DPP: Received SHA256(PK)",
-			    pk_hash, pk_hash_len);
-		wpa_hexdump(MSG_DEBUG, "DPP: Calculated SHA256(PK)",
-			    intro.nk_hash, SHA256_MAC_LEN);
-		goto fail;
-	}
-
-	nk_hash = dpp_get_attr(buf, len, DPP_ATTR_OWN_NET_NK_HASH,
-			       &nk_hash_len);
-	if (!nk_hash || nk_hash_len != SHA256_MAC_LEN) {
-		wpa_printf(MSG_DEBUG, "DPP: Peer did not include SHA256(NK)");
-		goto fail;
-	}
-	if (os_memcmp(nk_hash, intro.pk_hash, SHA256_MAC_LEN) != 0) {
-		wpa_printf(MSG_DEBUG, "DPP: SHA256(NK) mismatch");
-		wpa_hexdump(MSG_DEBUG, "DPP: Received SHA256(NK)",
-			    nk_hash, nk_hash_len);
-		wpa_hexdump(MSG_DEBUG, "DPP: Calculated SHA256(NK)",
-			    intro.pk_hash, SHA256_MAC_LEN);
-		goto fail;
-	}
-
 	entry = os_zalloc(sizeof(*entry));
 	if (!entry)
 		goto fail;
@@ -1872,10 +1860,15 @@ int wpas_dpp_check_connect(struct wpa_supplicant *wpa_s, struct wpa_ssid *ssid,
 		   MACSTR, MAC2STR(bss->bssid));
 
 	msg = dpp_alloc_msg(DPP_PA_PEER_DISCOVERY_REQ,
-			    4 + os_strlen(ssid->dpp_connector));
+			    5 + 4 + os_strlen(ssid->dpp_connector));
 	if (!msg)
 		return -1;
 
+	/* Transaction ID */
+	wpabuf_put_le16(msg, DPP_ATTR_TRANSACTION_ID);
+	wpabuf_put_le16(msg, 1);
+	wpabuf_put_u8(msg, TRANSACTION_ID);
+
 	/* DPP Connector */
 	wpabuf_put_le16(msg, DPP_ATTR_CONNECTOR);
 	wpabuf_put_le16(msg, os_strlen(ssid->dpp_connector));