Recently, a new light-weight version of the secure electronic transaction protocol was proposed. The protocol can achieve two goals. One goal is that the security level is the same as the SET protocol. The other goal is to reduce the computational time in message generation and verification, and reduce the communication overhead. However, the protocol has a weakness, which is that non-repudiation is acquired, but confidentiality is lost. In this paper, we point out the weakness of the protocol. We also propose an improvement to the protocol to overcome this weakness.