  Contact tracing is paramount to fighting the pandemic but it comes with
legitimate privacy concerns. This paper proposes a system enabling both,
contact tracing and data privacy.
  We propose the use of the Intel SGX trusted execution environment to build a
privacy-preserving contact tracing backend. While the concept of a confidential
computing backend proposed in this paper can be combined with any existing
contact tracing smartphone application, we describe a full contact tracing
system for demonstration purposes.
  A prototype of a privacy-preserving contact tracing system based on SGX has
been implemented by the authors in a hackathon.
