How Trail of Bits helps verify the integrity of Signal chats

Signal recently launched Automatic Key Verification, a feature that uses key transparency to prevent attackers from intercepting chats by providing false encryption keys. Trail of Bits operates one of three independent auditors that continuously verify the system's integrity by maintaining a Merkle tree of public keys and signing it periodically; if the server attempts to hide a malicious key, clients will detect inconsistencies and display warnings within seven days.