Yes, your assignment is stupid and asking for help is justifiable
Your professor is doing a poor job. His philosophy is probably that he will throw you in the lake and if you can swim you will have learned a lot, and if not, well then ... he probably did not care.
Being totally new in a field, and not having research experience, it is impossible to know which papers to start with. So I totally understand your questions.
Some of the answers to this post, the arrogant and unfriendly ones, come because people just imagine that the professor knows what he is doing. These people have probably gone to good universities. Crappy universities sometimes have really crappy professors.
Asking you to read five papers is stupid. It took me one day to read a paper, and I considered myself an average computer science student. The result of your assignment will be that most students just pretend. They write something about the protocol, and then browse each article to find at least one (perhaps irrelevant) fact to weave into the report.
When I wrote my thesis most of the literature was suggested by my professor. Note: That was my thesis! Your professor is sending you out of the classroom without recommending any...
My best suggestion would be
I can't suggest any articles. But the approaches below might work.
Asking someone who can give advice on which papers. I guess you didn't know any. Well, when I have a programming task that I can't solve I often use StackOverflow or other forums. So you could try and write in a forum. I would expect that in a security forum there would be people from the academic world, a PhD perhaps, that have worked with the field. They should be able to recommend a few articles. However, you must prepare for arrogant answers.
D.W. suggests reading the Wikipedia article and use those sources. That is a really good approach.
Another approach is to follow references in papers. This is not actually something I've practiced, but I imagine it would work. Browse (don't read) some random papers on the topic, and look at their references. There will probably be some papers that a lot of papers refer to. That probably means they are helpful sources, or just sources that form the basis. Pick one of those. Read it through, and make sure you understand it. Of course this article will be one of the five. In this article, when you've read it carefully, you will see references to other articles, and you will have some understanding of what these articles cover. Pick four more among these.