A note on modified SET protocol for mobile payment

Recently a modified SET protocol for mobile payment (MSET) has been proposed in the literature. MSET claims to be a promising protocol for mobile payment. However, we have observed certain flaws and drawbacks in the proposed protocol. In this paper we discuss those flaws and drawbacks and propose counter measures for the same to ensure secure transaction. The first flaw is that a dishonest client can buy goods from a merchant without paying the actual price of the goods. We also observed that the MSET protocol lacks the Non-Repudiation property of transaction. Further, we would like to mention that the modified SET is using certificate, which is having no use once the symmetric key is distributed. This causes communication overhead for the mobile application. As a result the protocol will be useful only for mobiles with reasonably high processing power. With the growing demand of mobile based payment systems in developing countries this could be a disadvantage.