Bluetooth: Add option for disabling data signing support

This allows to not compile data signing support if it is not
required. Reduces image size of peripheral sample app from
45772 to 44436 bytes.

Change-Id: I2cd3515973d1a70f478cbd68426ec84fd1645d19
Signed-off-by: Szymon Janc <ext.szymon.janc@tieto.com>

net/bluetooth/Kconfig

@@ -54,6 +54,14 @@ config BLUETOOTH_CENTRAL
 	select BLUETOOTH_CONN
 
 if BLUETOOTH_PERIPHERAL || BLUETOOTH_CENTRAL
+config BLUETOOTH_SIGNING
+	bool
+	prompt "Data signing support"
+	default n
+	help
+	  This option enables data signing which is used for transferring
+	  authenticated data in an unencrypted connection.
+
 config	BLUETOOTH_MAX_CONN
 	int
 	prompt "Maximum number of simultaneous connections"

net/bluetooth/keys.h

@@ -71,8 +71,10 @@ struct bt_keys {
 	struct bt_ltk		slave_ltk;
 	struct bt_ltk		ltk;
 	struct bt_irk		irk;
+#if defined(CONFIG_BLUETOOTH_SIGNING)
 	struct bt_csrk		local_csrk;
 	struct bt_csrk		remote_csrk;
+#endif /* BLUETOOTH_SIGNING */
 };
 
 struct bt_keys *bt_keys_get_addr(const bt_addr_le_t *addr);

net/bluetooth/smp.c

@@ -57,8 +57,13 @@
 #include "l2cap.h"
 #include "smp.h"
 
+#if defined(CONFIG_BLUETOOTH_SIGNING)
 #define RECV_KEYS (BT_SMP_DIST_ID_KEY | BT_SMP_DIST_ENC_KEY | BT_SMP_DIST_SIGN)
 #define SEND_KEYS (BT_SMP_DIST_ENC_KEY | BT_SMP_DIST_SIGN)
+#else
+#define RECV_KEYS (BT_SMP_DIST_ID_KEY | BT_SMP_DIST_ENC_KEY)
+#define SEND_KEYS (BT_SMP_DIST_ENC_KEY)
+#endif /* CONFIG_BLUETOOTH_SIGNING */
 
 enum pairing_method {
 	JUST_WORKS,		/* JustWorks pairing */
@@ -194,6 +199,7 @@ static void xor_128(const uint128_t *p, const uint128_t *q, uint128_t *r)
 	r->b = p->b ^ q->b;
 }
 
+#if defined(CONFIG_TINYCRYPT_AES) || defined(CONFIG_BLUETOOTH_SIGNING)
 /* swap octets for LE encrypt */
 static void swap_buf(const uint8_t *src, uint8_t *dst, uint16_t len)
 {
@@ -215,6 +221,7 @@ static void swap_in_place(uint8_t *buf, uint16_t len)
 		buf[j] = tmp;
 	}
 }
+#endif /* CONFIG_TINYCRYPT_AES || CONFIG_BLUETOOTH_SIGNING */
 
 #if defined(CONFIG_TINYCRYPT_AES)
 static int le_encrypt(const uint8_t key[16], const uint8_t plaintext[16],
@@ -993,6 +1000,7 @@ static void bt_smp_distribute_keys(struct bt_conn *conn)
 		bt_l2cap_send(conn, BT_L2CAP_CID_SMP, buf);
 	}
 
+#if defined(CONFIG_BLUETOOTH_SIGNING)
 	if (smp->local_dist & BT_SMP_DIST_SIGN) {
 		struct bt_smp_signing_info *info;
 
@@ -1013,6 +1021,7 @@ static void bt_smp_distribute_keys(struct bt_conn *conn)
 
 		bt_l2cap_send(conn, BT_L2CAP_CID_SMP, buf);
 	}
+#endif /* CONFIG_BLUETOOTH_SIGNING */
 }
 
 static uint8_t smp_encrypt_info(struct bt_conn *conn, struct bt_buf *buf)
@@ -1158,6 +1167,7 @@ static uint8_t smp_ident_addr_info(struct bt_conn *conn, struct bt_buf *buf)
 	return 0;
 }
 
+#if defined(CONFIG_BLUETOOTH_SIGNING)
 static uint8_t smp_signing_info(struct bt_conn *conn, struct bt_buf *buf)
 {
 	struct bt_smp_signing_info *req = (void *)buf->data;
@@ -1185,6 +1195,12 @@ static uint8_t smp_signing_info(struct bt_conn *conn, struct bt_buf *buf)
 
 	return 0;
 }
+#else
+static uint8_t smp_signing_info(struct bt_conn *conn, struct bt_buf *buf)
+{
+	return BT_SMP_ERR_CMD_NOTSUPP;
+}
+#endif /* CONFIG_BLUETOOTH_SIGNING */
 
 #if defined(CONFIG_BLUETOOTH_CENTRAL)
 static uint8_t smp_security_request(struct bt_conn *conn, struct bt_buf *buf)
@@ -1393,7 +1409,7 @@ bool bt_smp_irk_matches(const uint8_t irk[16], const bt_addr_t *addr)
 	return !memcmp(addr->val, hash, 3);
 }
 
-
+#if defined(CONFIG_BLUETOOTH_SIGNING)
 /* 1 bit left shift */
 static void array_shift(const uint8_t *in, uint8_t *out)
 {
@@ -1672,6 +1688,17 @@ int bt_smp_sign(struct bt_conn *conn, struct bt_buf *buf)
 
 	return 0;
 }
+#else
+int bt_smp_sign_verify(struct bt_conn *conn, struct bt_buf *buf)
+{
+	return -ENOTSUP;
+}
+
+int bt_smp_sign(struct bt_conn *conn, struct bt_buf *buf)
+{
+	return -ENOTSUP;
+}
+#endif /* CONFIG_BLUETOOTH_SIGNING */
 
 #if defined(CONFIG_BLUETOOTH_SMP_SELFTEST)
 /* Test vectors are taken from RFC 4493

samples/bluetooth/shell/prj_arm.conf

@@ -6,3 +6,4 @@ CONFIG_BLUETOOTH_DEBUG=y
 CONFIG_CONSOLE_HANDLER=y
 CONFIG_BLUETOOTH_CENTRAL=y
 CONFIG_BLUETOOTH_PERIPHERAL=y
+CONFIG_BLUETOOTH_SIGNING=y

samples/bluetooth/shell/prj_x86.conf

@@ -6,5 +6,6 @@ CONFIG_BLUETOOTH_UART=y
 CONFIG_CONSOLE_HANDLER=y
 CONFIG_BLUETOOTH_CENTRAL=y
 CONFIG_BLUETOOTH_PERIPHERAL=y
+CONFIG_BLUETOOTH_SIGNING=y
 CONFIG_TINYCRYPT=y
 CONFIG_TINYCRYPT_AES=y

samples/bluetooth/tester/prj_arm.conf

@@ -5,6 +5,7 @@ CONFIG_BLUETOOTH=y
 CONFIG_BLUETOOTH_UART=y
 CONFIG_BLUETOOTH_CENTRAL=y
 CONFIG_BLUETOOTH_PERIPHERAL=y
+CONFIG_BLUETOOTH_SIGNING=y
 CONFIG_BLUETOOTH_DEBUG=y
 CONFIG_BLUETOOTH_DEBUG_HCI_CORE=y
 CONFIG_BLUETOOTH_DEBUG_BUF=y