  Cloud computing has been a dominant paradigm for a variety of information
processing platforms, particularly for enabling various popular applications of
sharing economy. However, there is a major concern regarding data privacy on
these cloud-based platforms. This work presents novel cloud-based
privacy-preserving solutions to support collaborative consumption applications
for sharing economy. In typical collaborative consumption, information
processing platforms need to enable fair cost-sharing among multiple users for
utilizing certain shared facilities and communal services. Our cloud-based
privacy-preserving protocols, based on homomorphic Paillier cryptosystems, can
ensure that the cloud-based operator can only obtain an aggregate schedule of
all users in facility sharing, or a service schedule conforming to service
provision rule in communal service sharing, but is unable to track the personal
schedules or demands of individual users. More importantly, the participating
users are still able to settle cost-sharing among themselves in a fair manner
for the incurred costs, without knowing each other's private schedules or
demands. Our privacy-preserving protocols involve no other third party who may
compromise privacy. We also provide an extensive evaluation study and a
proof-of-concept system prototype of our protocols.
