And why exactly would this not be a right site? Is this web site not about computer security? Is this forum not about security programming? Is he asking how to gcc some exploit or something? In fact, this is the kind of thing that should be in this forum. I'm not a regular at this website, but I see no reason for his post not to belong here. I'm sure he, as most of other C programmers is familiar with cprogramming.com . Why posting a link, instead of help or at least your opinion about the correct possible answer???

Anyway, Encrypted, Using

system() isn't smart because your program executes shell commands. Now, if it had root perm ... get the point?

sprintf() - I am really gonna be guesing here, but will look up later (5.46 am here). Since it has infinite size, there might be certain issue with DoS.