detail explanation needed

1. [30] A large e-commerce operator (with payment interface) collects customers' data and utilizes third party vendors to perform advanced data analytics for providing value added services to customers. (a) [5] What are the various security threats that specifically apply for this e-commerce operator? (b) [7] How would you go about designing usability studies for building such platform? (c) [10] Design a usable data sharing protocol with built in security mechanisms to prevent data theft and manipulation. Why would it work for this specific scenario? (d) [8] What sort of guarantees does the protocol described in (c) provide for data confidentiality and integrity? Describe specific scenarios where they fail