Secure Electronic Transactions (SET) is a security protocol for an electronic payment system that utilizes PKI to address e-commerce security and privacy concerns. Although PKI technologies used by the SET protocol were proven to be effective in addressing security issues in e-commerce, several implementation issues were found from SET applications de-signed to support security mechanisms of PKI. SET failed to be implemented by e-commerce end-users. This paper studies how SET was predicted, designed, and rejected by e-commerce end-users. PKI issues associated with SET implementation in B2C e-commerce are also reviewed. Although e-commerce end-users are concerned about security issues, usability is a more dominant factor than security for a secure system project to be adopted by the users.