Building Private Processing for AI tools on WhatsApp

Introduced Private Processing for AI tools on WhatsApp, a new confidential computing infrastructure built on Trusted Execution Environments (TEEs). This system enables AI processing of messages in a secure and private cloud environment, ensuring that neither Meta nor WhatsApp can access user data. Key technical components include anonymous credentials for authentication, Oblivious HTTP (OHTTP) for routing and encryption via third-party relays, and Remote Attestation + Transport Layer Security (RA-TLS) sessions for secure communication between the user's device and the TEE. The system is designed with foundational requirements for confidential processing, enforceable guarantees, and verifiable transparency, along with additional layers for non-targetability and stateless processing with forward security. A detailed threat model was developed, considering assets, threat actors (insiders, third parties, malicious end users), and threat scenarios such as external exploitation of product attack surface, extraction of messages from CVMs, and interference with CVMs at boot and runtime.