LAB4作业完整版.doc

Laboratory Two – Decoding Lab (Part 1) Objectives: For this exercise, you have to compile a program as attached and supply four secret keys to determine the contents. In this laboratory, you have to supply the first two. The remaining will be done next week. I will guide you to solve the problem. This exercise is extracted from the CTE, SSD6 – Exercise one. The details are as follows. Start the program: invoke the visual C++ and use new to start the workplace. Select the New Menu and click “workplace”. The name is called exercise 1 The project is exercise 1: Select Win32 Console The output after selecting the project is as follows. Select the empty button until you see the following screen Now Select New again and then Files, type the name of file “Exercise 1” and select C++ source file. Click the fileview and the source files you will see exercise1.cpp is there, but is empty. Now you download the secret file (secret.cpp) from CTE web site or get it from appendix. Compile the program without any bug. Set a breakpoint: Set a break point to force the program to break, press F9. A good programmer must know how to debug. Press F9 at the location of int dummy under main() Now Click Debug and choose start debug then go, you will see the screen It means the program stops at this location, You can now dummy the message to analysis the data. Right click your mouse and you will get a screen as follows: Select quick watch and you will see a quick watch Type the data and write the address Address of data is: _______________ (hint: in hex, ox……..) In the address screen: Enter the value of the address of data: 0x_______________. You can see the value of on the right hand side. Write down the first 40 characters. Determine the value of start and stride: [Hint] Now you find that if you can extract the message, pick the start message and then the stride (after how many characters for the next), you can then guess how to determine it. For example, 1234567890A Start:0 and