Betrusted: Improving Security Through Physical Partitioning

Abstract

Security requires attention. Anyone who has forgotten to lock their front door because they were distracted by an incoming call can attest to this. The condensation of virtually everything into a single device-the smartphone-has normalized deviant behaviors that create security risks. For example, many smartphone users conduct secure transactions while juggling several other apps, thus creating opportunities for adversaries to exploit human error. Furthermore, both secure and insecure code run on a smartphone's common CPU, thus exposing user secrets to a large and complex attack surface with multiple microarchitectural side channels. This article proposes partitioning a set of secure applications into a physically separate device that is designed using security-first principles. We call this device “Betrusted.” Putting secure apps on a separate screen helps users focus on their secure transactions while minimizing attack surfaces and eliminating microarchitectural sidechannels.