Doubts about the problem-solving process.
Xiaobai's learning record, the master does not spray, welcome to communicate.
In this problem, both join and strcat are functions that realize splicing characters. But in the process of solving the problem, I found that when concatenating the src and v9 strings, the two strings should be connected in reverse, that is, key3 + "hadow" and key + "NDCLS".
For the time being, it is assumed that the data is taken out according to the stack, just like the access bytes in the assembly. I do n’t know how to learn art, and I did n’t find relevant information on the Internet. I think so and leave doubts.
There is a modulo operation here. If you want to decrypt it, you need a modulo inverse operation. But I haven't thought of how to do the inverse modular operation. I might have to deal with the number theory knowledge here. I will point it out here for later modification. I used brute force to solve the problem here. Every traversal, if it meets the conditions, then break again.