  The recent proliferation of smart devices has given rise to ubiquitous
computing, an emerging computing paradigm which allows anytime & anywhere
computing possible. In such a ubiquitous computing environment, customers
release different computing or sensing tasks, and people, also known as data
processors, participate in these tasks and get paid for providing their idle
computing and communication resources. Thus, how to select an appropriate and
reliable customer while not disclosing processors' privacy has become an
interesting problem. In this article, we present a trust-based and
privacy-preserving customer selection scheme in ubiquitous computing, called
TPCS, to enable potential processors select the customers with good reputation.
The basic concept of TPCS is that each data processor holds a trust value, and
the reputation score of the customer is calculated based on processors' trust
values and feedbacks via a truth discovery process. To preserve processors'
privacy, pseudonyms and Paillier cryptosystem are applied to conceal each
processor's real identity. In addition, three authentication protocols are
designed to ensure that only the valid data processors (i.e., the processors
registering in the system, holding the truthful trust values, and joining the
computing tasks) can pass the authentication. A comprehensive security analysis
is conducted to prove that our proposed TPCS scheme is secure and can defend
against several sophisticated attacks. Moreover, extensive simulations are
conducted to demonstrate the correctness and effectiveness of the proposed
scheme.
