Abstract: To solve the security issues in the mobile payment, this paper designs a mobile payment protocol based on CA system which uses the digital certificate to bind the user identity and public key. There are tow protocols included: (a) remote mobile payment protocol; (b) on-site payment protocol. The protocols provide mobile network users or Internet network users with information encryption and decryption and digital signature, provide users and information service providers with identity authentication and data authentication, which assures the confidentiality of transaction informa- tion, non-repudiation and integrity, prevents replay attacks, and basically solves the ccommerce security issue.

Key words: Mobile payment, Digital certificate, Digital signature, Integrity