| According to the provisions of the State Secrecy Bureau, secret departments need to distinguish the computers concerned secret and the ones not. Secret computers must be physically isolated from commonly used computers, and removable storage media is strictly forbidden. However, people need to obtain much information from outside in the Information Age, especially real-time cutting-edge information. Physical isolation greatly decreases work efficiency and increases cost. Therefore, it is meaningful to research on data transmission between different security levels.According to Bell-LaPudula security model, a unidirectional data transmission solution based on removal storage media is proposed. On low security level computers, data can only be written to the storage media; while on high security level computers, data can only be read from the storage media. Thus, the storage media only contains non-secret information, and secret information is safe from leaking. The device consists of USB interface module and unidirectional data transmission module. The USB interface module is used to read/write U disks and communicate with hosts. Two ARM chips are in charge respectively. Embedded Linux is built on both chips to lower developing difficulties. The ARM chips communicate only through the unidirectional data transmission module to provide the overall unidirectional transmission.Firstly, the dissertation introduces the background, the basic research concept, the status quo and the significance of the research. Secondly, the dissertation proposes the overall design, introduces the digital circuit and underlying software design in detail. Finally, it summarizes the work of the dissertation and prospects the future work.After tests, the speed between two modules can reach202Mbps and135Mbps on the transmission and reception side. File transmission speed averages about103Mbps, which exceeds common U disks and satisfies basic needs. |
PDF Full Text Request