This add-on stores your IIT Kharagpur ERP roll number, password, and security answers in browser storage on your device. If you set a 4-digit PIN, those values are encrypted with it. They are used only to fill the login form on erp.iitkgp.ac.in. They are not sent to the add-on author or to any other server. You can delete them with Clear & Reset in the add-on popup.