validate the keyselector in imeplementation of get session key APIs

Author: dhineshkumarmcci

src/se/drivers/default/lmic_se_default.c

@@ -154,6 +154,8 @@ In this function the nwkskey is passed to upper layer of LMIC.
 
 LMIC_SecureElement_Error_t
 LMIC_SecureElement_Default_getNwkSKey(LMIC_SecureElement_Aes128Key_t *pNwkSKey, LMIC_SecureElement_KeySelector_t iKey) {
+    if (iKey != LMIC_SecureElement_KeySelector_Unicast)
+        return LMIC_SecureElement_Error_InvalidParameter;
     os_copyMem(pNwkSKey->bytes, s_nwkSKey.bytes, sizeof(pNwkSKey->bytes));
 }
 
@@ -169,6 +171,8 @@ In this function the appskey is passed to upper layer of LMIC.
 
 LMIC_SecureElement_Error_t
 LMIC_SecureElement_Default_getAppSKey(LMIC_SecureElement_Aes128Key_t *pAppSKey, LMIC_SecureElement_KeySelector_t iKey) {
+    if (iKey != LMIC_SecureElement_KeySelector_Unicast)
+        return LMIC_SecureElement_Error_InvalidParameter;
     os_copyMem(pAppSKey->bytes, s_appSKey.bytes, sizeof(pAppSKey->bytes));
 }