In class, we gave a very basic macro design to implement stack guard with canary. In

that design, we haven$$t talk about how to define $\_\_$SECRET$\_$VAR in the macros. A

simple way to define $\_\_$SECRET$\_$VAR is some marco like

#define $\_\_$SECRET$\_$VAR $11223344$

But the issue is that it is a constant so an attacker can know. A better strategy is to make

it a variable and assign a random number to it at run time.