| With the conveniences USB interface providing to the users,some potential dangers appear companied with its advantage.And the USB interface has been an impormant I/O channel which unauthorized users can resort to to access the system security resources.Both of Microsoft and third-party manufacturers provide some solutions to users for USB access control.But,all of the solutions carry out in Windows,so,when Windows security is destroied,no solution can ensure the effectiveness.Based on ENSS card which is an achievement of a National 863 project called "A safe terminal technology of windows based on Dual-Core and Dual-OS",an USB module is added for USB access control in this paper.USB access control solutions can be carried out by the Linux which runs in the secure terminal.So when the Windows security is destroied,we can ensure the effectiveness all the same.For adding USB module to ENSS card,this paper designs two solutions.After balancing the advantages against the disadvantages,the paper decides to employ the "Based on the independent channel"solution.Based on this solution,the paper redesigns the ENSS circuit,and adds the USB interface.The paper also retransplantations the Linux operation system,and improves its performance.At the same time,the paper researches and analysises the USB controller drivers and client software,optimizes the I/O operation steps for improving USB communication speed.As for U disk access control,the paper designs and realizes three solutions.And they are based on information direction access control mechanism,based on information content access control mechanism,and based on user ID access control mechanism.What is more, the paper tests these mechanisms's access control effects.At last,based on the three mechanisms,the paper designs a role of multi-level strategy to manage the U disk users.In the experiment,making use of the methods above,unauthorized users can be prevented from accessing the system security resources via the USB interface. |
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