In recent past SMS (Short Message Service) has become very popular data bearer in GSM networks. SMS, inherently being a messaging protocol, has always been point-to-point and in plaintext. For m-commerce transactions, SMS will be routed through public networks and some application servers of the merchant. Also, to protect itself against unknown roaming environments, SMS needs peer-to-peer object level security at the application level. This demands SMS to offer trustworthy model. The paper uses a novel philosophy to establish trust between users and services. We presented a model of trust and application level public key encryption of SMS with client authentication using JavaCard technology over GSM 03.48.