Today I am going to write about how to do dynamic analyses of our keygen challenge with IDA Pro. In order to make you easier to do the dynamic analyses, you should change variable/function name and add line comments so that it will be more descriptive.
You can use ‘n’ button on the function or varibale name to rename them like the image below
I would change the call __ZNKSs4sizeEv to Get_Array_Size
in order to give comment to your code, you can use ‘;’ and put your description for the line that you want to comment
If you are using Ghidra to reverse, It has the same capabilities like IDA to rename and make comment using different button ‘l’ to rename function or variable name
It is important step to be done prior your dynamic analyses in order to make it easier to read and remember
here is below for the 3 first check
So what does this mean ? Based on the above condition, Our array lenght must be 16 chars and the first char shall be between 64 to 90 in decimal