Key Transparency Comes to Messenger

What this post added

Introduced key transparency verification for end-to-end encrypted chats on Messenger, building upon WhatsApp's implementation. Leverages the Auditable Key Directory (AKD) library and Cloudflare's key transparency auditor. Addressed engineering challenges related to high volume and frequency of key updates by optimizing algorithmic efficiency for smaller proof sizes and improving infrastructure resilience to outages and sequencing delays. This allows users to automatically verify the authenticity of their contacts' encryption keys for one-on-one chats.