I agree with rolf on how difficult, costly and ineffective trying to implement this sort of "security" over the internet can be. I cannot imagine anything beyond setting up simple html pages protected by username/passwords. This does very little to prevent leaks, but at least it will give your customers a sense of confidentiality.
Alternatively you could try to work with it, not against it. Copying can be free publicity, and an measure of how much people like the article.
If possible, this is the best choice you could make.