Abstract: The present invention relates to a method and system for mutual authentication of a user and service provider, said method comprising acts of: authenticating an event by a key generation module (KGM), said event is generated on a computing device by a user, sending a shared secret of registered user for the event by an authentication server to the key generation module (KGM), generating one time key by the KGM for the event, transmitting the one time key by appending the shared secret to registered user mobile device, and performing at least one of: authenticating the user for said event by the KGM when a registered user enters the one-time key on the computing device within a predetermined time period, or terminating the event upon receipt of predefined key sequence from the mobile device.