This book describes an authentication protocol implemented using OffPAD device ( https://www.offpad.org) and a server. This authentication protocol is used for securing online banking transactions from intruders. It used a mobile app , browser plugin and secure channel for transmission of vital data. In the online banking systems, authentication has always been the focus point due to increasing security threats. There have been various authentication systems tested and implemented for securing the user and data authentication. Among all entities of the online banking system, the client is the most vulnerable entity in terms of security threats. So the main focus of this book is to provide an authentication mechanism that preserves security even if the client is infected or has security vulnerabilities.