IPLS: Privacy-preserving storage for your WhatsApp contacts
Oct 22, 2024Slavik Krassovsky, Kevin Lewi, Dillon George, Cheng Tian, Ercan Ozturk
Summary
Introduced Identity Proof Linked Storage (IPLS) for WhatsApp, a novel encrypted storage system that allows users to save and automatically restore contact lists directly through WhatsApp. IPLS leverages existing technologies like key transparency (via Auditable Key Directory - AKD) and hardware security modules (HSMs) for private, tamper-resistant execution. It integrates with Cloudflare as an independent witness for AKD updates and uses HSM-based key storage for encrypted contact names, ensuring availability and privacy even if a phone is lost. This enables users to create and manage contacts within WhatsApp, sync them across linked devices, and customize contact lists for multiple accounts on the same phone.
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