At-rest encryption is not something that Signal Desktop is currently trying to provide or has ever claimed to provide. Full-disk encryption can be enabled at the OS level on most desktop platforms.

Researchers have developed a proof-of-concept side-channel attack that allows them to pull encryption keys from a single decryption for a modern version of OpenSSL.

The encryption being added, known as PQ3, is an implementation of a new algorithm called Kyber that, unlike the algorithms iMessage has used until now, can’t be broken with quantum computing.

The Signal Protocol used by 1+ billion people is getting a post-quantum makeover Update prepares for the inevitable fall of today's cryptographic protocols.