In order to address the security and privacy issues for future e-healthcare systems using lightweight RFID (radio frequency identification) technology,a generalized medical processing model is built,and an improved scheme on existing protocols is thus proposed.In this new scheme,information from the immediate predecessors is fully used to reduce the searching space.Security analysis shows that it can effectively tradeoff the conflicts between the security and scalability,resist all kinds of attacks,support the reuse of RFID tags,and conform to current EPC C1G2 standards.