Abstract: Disclosed herein is a method and system that addresses the need of securing an online transaction of a consumer. The user is provided with a client application on a mobile device. The user registers the mobile device on a transaction server. The user inputs transaction details for the online transaction on a web portal hosted on the transaction server. The transaction server creates a challenge to the user on a confirmation page to confirm the online transaction. The challenge comprises a challenge code and a transaction confirmation image. The graphical image and the transaction details are computationally inseparable in real time. The user conveys the challenge to the mobile device by inputting the challenge code in the client application. The client application generates a response for the challenge. The user then inputs the response on the confirmation page. The transaction server validates the response and authorizes the online transaction.