diff --git a/example/Makefile.inc b/example/Makefile.inc
index e8f4a25e8..cb8d199c3 100644
--- a/example/Makefile.inc
+++ b/example/Makefile.inc
@@ -2,11 +2,13 @@ VPATH += ${BTSTACK_ROOT}/src
 VPATH += ${BTSTACK_ROOT}/src/ble
 VPATH += ${BTSTACK_ROOT}/src/classic
 VPATH += ${BTSTACK_ROOT}/example
+VPATH += ${BTSTACK_ROOT}/3rd-party/mbedtls/library
 
 CFLAGS += -I.
 CFLAGS += -I${BTSTACK_ROOT}/src/ble
 CFLAGS += -I${BTSTACK_ROOT}/src/classic
 CFLAGS += -I${BTSTACK_ROOT}/src
+CFLAGS += -I${BTSTACK_ROOT}/3rd-party/mbedtls/include
 
 CORE += \
     btstack_memory.c            \
@@ -54,6 +56,11 @@ SM_MINIMAL += \
 PAN += \
 	pan.c \
 
+MBEDTLS = 					\
+	bignum.c 				\
+	ecp.c 					\
+	ecp_curves.c 			\
+
 EXAMPLES = 					\
 	ancs_client_demo		\
 	gap_dedicated_bonding	\
@@ -87,7 +94,7 @@ EXAMPLES_USING_LE =			\
 # .o for .c
 CORE_OBJ    = $(CORE:.c=.o)
 COMMON_OBJ  = $(COMMON:.c=.o) 
-SM_REAL_OBJ = $(SM_REAL:.c=.o)
+SM_REAL_OBJ = $(SM_REAL:.c=.o) $(MBEDTLS:.c=.o)
 SM_MINIMAL_OBJ = $(SM_MINIMAL:.c=.o)
 ATT_OBJ     = $(ATT:.c=.o)
 GATT_CLIENT_OBJ = $(GATT_CLIENT:.c=.o)
diff --git a/example/le_counter.c b/example/le_counter.c
index 38a0baff6..c210191da 100644
--- a/example/le_counter.c
+++ b/example/le_counter.c
@@ -98,6 +98,9 @@ static void le_counter_setup(void){
 
     // setup SM: Display only
     sm_init();
+#ifdef ENABLE_LE_SECURE_CONNECTIONS
+    sm_set_authentication_requirements(SM_AUTHREQ_SECURE_CONNECTION);
+#endif
 
     // setup ATT server
     att_server_init(profile_data, att_read_callback, att_write_callback);    
diff --git a/example/le_counter.gatt b/example/le_counter.gatt
index fb0e8a549..a9aad864b 100644
--- a/example/le_counter.gatt
+++ b/example/le_counter.gatt
@@ -8,5 +8,7 @@ CHARACTERISTIC, GATT_SERVICE_CHANGED, READ,
 PRIMARY_SERVICE, 0000FF10-0000-1000-8000-00805F9B34FB
 // Counter Characteristic, with read and notify
 CHARACTERISTIC,  0000FF11-0000-1000-8000-00805F9B34FB, READ | NOTIFY | DYNAMIC,
+// Counter Characteristic, with read and notify + authentication
+CHARACTERISTIC,  0000FF12-0000-1000-8000-00805F9B34FB, READ | NOTIFY | DYNAMIC | AUTHENTICATION_REQUIRED,
 
 
diff --git a/port/libusb/btstack_config.h b/port/libusb/btstack_config.h
index c42181cbe..c424fc133 100644
--- a/port/libusb/btstack_config.h
+++ b/port/libusb/btstack_config.h
@@ -14,6 +14,7 @@
 // BTstack features that can be enabled
 #define ENABLE_BLE
 #define ENABLE_CLASSIC
+#define ENABLE_LE_SECURE_CONNECTIONS
 #define ENABLE_LOG_ERROR
 #define ENABLE_LOG_INFO 
 #define ENABLE_LOG_INTO_HCI_DUMP