Year according to a wiki page on the unofficial Signal wiki the backup will not be directly linked to the user “It appears that backups will not be directly linkable to a user. Authentication for operations against a given backup will use zero-knowledge proofs.”.
Cloud backups, for security!
If anyone is actually going to get that right in a mainstream product, it will probably be Signal.
Year according to a wiki page on the unofficial Signal wiki the backup will not be directly linked to the user “It appears that backups will not be directly linkable to a user. Authentication for operations against a given backup will use zero-knowledge proofs.”.