Service or software for managing tasks with data encryption and the ability to synchronize

Question

Task Management

Requirements:
- applications for android and desktop OS (WIndos, Linux)
- data storage does not have to take place on the servers of the service, it can be on some dropbox, but I have no idea how synchronization between windows and android will look like, for example
- data must be stored encrypted using strong cryptographic algorithms
- Ability to use for personal needs, not for the team.
thank.

Answer 1

As a variant of duplicity, you can at least encrypt the entire disk.

Answer 2

"The ability to use for personal needs, not for the team." and "command" will be used? Personal, etc.