Abstract: A method and system for secure transactions. The method and system comprise a security co-processor and an interface for interfacing the security co-processor to a host computer system. The method and system wherein secure transaction processing is performed locally in the security co-processor and non-secure transaction processing is performed in the host computer system. The method and system further include means for providing trusted input coupled to the security co-processor. In addition, the method and system include a second interface coupled to the security co-processor for receiving sensitive data from a smart card, and a trusted display coupled to the security co-processor for providing true transaction information. One advantage of the method and system in accordance with the present invention is that transactions are protected from unauthorized intrusion and, in addition, participation is proven so that transactions cannot be repudiated.