摘要 |
Executable software 30B is protected by inserting an additional block of code 50, immediately after the header 30A. The block 50 is executable to analyse all or part of the structure 30 to determine whether or not any change has been made to the structure after the creation of the structure. For example, a CRC value may be checked. When the software 30B is to be executed, the security block 50 executes first, to check if any changes have been made, such as by the effect of a virus. If this is detected, a compressed copy 52 is used to replace at least the program region 30B, prior to execution being handed to the block 30B. |