I want a dog to protect me because I'm going to become homeless. What can I do to make a dog aggressive towards people?

Ok, this might sound bad, but I'm going to become Homeless this year and I'm a Girl. So I, want to get a dog to protect me. So I want it to be aggressive toward people. I know its a liablity and dangerous but I don't have $$ for protection training. Is there certain thing or things I can do to making him this way. And is there a test I can do on him to see if he can be aggressive? I'm think of getting a German Shepherd or American Pitbull Terrier. 6-10 months old.

Also I would be very careful with him around friends and make sure he wears a muzzle.

Thank You