Private delegated computations using strong isolation

TL;DR

This paper introduces Veracruz, a framework that simplifies the development and deployment of privacy-preserving delegated computations across various isolation technologies, including hardware-backed and software-based solutions, demonstrated with real-world applications.

Contribution

Veracruz provides a unified programming model and attestation protocol for multiple isolation technologies, enabling secure delegated computations even on legacy devices without hardware Confidential Computing support.

Findings

Successfully deployed private in-cloud object detection on encrypted video streams

Supports multiple isolation technologies including hardware and software isolates

Demonstrates practical deployment on diverse hardware platforms

Abstract

Sensitive computations are now routinely delegated to third-parties. In response, Confidential Computing technologies are being introduced to microprocessors, offering a protected processing environment, which we generically call an isolate, providing confidentiality and integrity guarantees to code and data hosted within -- even in the face of a privileged attacker. Isolates, with an attestation protocol, permit remote third-parties to establish a trusted "beachhead" containing known code and data on an otherwise untrusted machine. Yet, the rise of these technologies introduces many new problems, including: how to ease provisioning of computations safely into isolates; how to develop distributed systems spanning multiple classes of isolate; and what to do about the billions of "legacy" devices without support for Confidential Computing? Tackling the problems above, we introduce Veracruz, a framework that eases the design and implementation of complex privacy-preserving, collaborative, delegated computations among a group of mutually mistrusting principals. Veracruz supports multiple isolation technologies and provides a common programming model and attestation protocol across all of them, smoothing deployment of delegated computations over supported technologies. We demonstrate Veracruz in operation, on private in-cloud object detection on encrypted video streaming from a video camera. In addition to supporting hardware-backed isolates -- like AWS Nitro Enclaves and Arm Confidential Computing Architecture Realms -- Veracruz also provides pragmatic "software isolates" on Armv8-A devices without hardware Confidential Computing capability, using the high-assurance seL4 microkernel and our IceCap framework.