a) We discussed TOR, which enables, for example, anonymous Internet browsing. Briefly explain how TOR provides anonymous Internet browsing. You can draw a figure to illustrate your argumentation. TOR also allows so called hidden services. Please briefly explain what a hidden service is and how TOR enables it.

You can draw a figure to illustrate your argumentation.

b) Describe the MapReduce algorithm.

Split it into its phases. For each phase include: what it does and who is responsible (the MapReduce framework or the programmer).