  The next generation of cellular networks will be characterized by openness,
intelligence, virtualization, and distributed computing. The Open Radio Access
Network (Open RAN) framework represents a significant leap toward realizing
these ideals, with prototype deployments taking place in both academic and
industrial domains. While it holds the potential to disrupt the established
vendor lock-ins, Open RAN's disaggregated nature raises critical security
concerns. Safeguarding data and securing interfaces must be integral to Open
RAN's design, demanding meticulous analysis of cost/benefit tradeoffs.
  In this paper, we embark on the first comprehensive investigation into the
impact of encryption on two pivotal Open RAN interfaces: the E2 interface,
connecting the base station with a near-real-time RAN Intelligent Controller,
and the Open Fronthaul, connecting the Radio Unit to the Distributed Unit. Our
study leverages a full-stack O-RAN ALLIANCE compliant implementation within the
Colosseum network emulator and a production-ready Open RAN and 5G-compliant
private cellular network. This research contributes quantitative insights into
the latency introduced and throughput reduction stemming from using various
encryption protocols. Furthermore, we present four fundamental principles for
constructing security by design within Open RAN systems, offering a roadmap for
navigating the intricate landscape of Open RAN security.
