| 摘要 |
PROBLEM TO BE SOLVED: To execute only a properly signed program code by a computing device, and to ensure that the program code is not modified or changed before it is executed. SOLUTION: This system comprises a memory and a processor that support different privilege levels. Only a program code executing at a certain privilege level is permitted to map the memory, and to assign access permission to the mapped memory, such as read-only, writable, and executable. A control code executed on the processor at this privilege level in response to a request from the other code executed at the different privilege level, maps a portion of the memory for loading an executable file. After the executable file has been loaded into the mapped memory, the control code then verifies a signature associated with the executable file. When the signature is verified, the control code permits the executable file to be executed by the processor at a privilege level other than the one at which the control code is executed. COPYRIGHT: (C)2006,JPO&NCIPI |
