  The order-preserving encryption (OPE) problem was initially formulated by the
database community in 2004 soon after the paradigm database-as-a-service (DaaS)
was coined in 2002. Over the past two decades, OPE has drawn tremendous
research interest from communities of databases, cryptography, and security; we
have witnessed significant advances in OPE schemes both theoretically and
systematically. All existing OPE schemes assume that the outsourced database is
modeled as a single semi-honest adversary who should learn nothing more than
the order information of plaintext messages up to a negligible probability.
This paper addresses the OPE problem from a new perspective: instead of
modeling the outsourced database as a single semi-honest adversary, we assume
the outsourced database \textit{service} compromises a cluster of non-colluding
servers, which is a practical assumption as all major cloud vendors support
multiple database instances deployed to exclusive sub-networks or even to
distinct data centers. This assumption allows us to design a new stateless OPE
protocol, namely order-preserving database encryption with secret sharing
(ODES), by employing secret-sharing schemes among those presumably
non-colluding servers. We will demonstrate that ODES guarantees the latest
security level, namely IND-FAOCPA, and outperforms the state-of-the-art scheme
by orders of magnitude.
