todoist save people data to where? is it secury?
if user account/pass was crack, have other ways stop it happe
All your data is stored very securely on one of the world's largest and most trusted hosts - Amazon Web Services.
However, if you share your password with someone, then it's of course possible for this person to log into your account. It's not possible to get your password in any other way, though because we are hashing and salting passwords in our database so they're not stored anywhere directly.
Is the task data also encrypted?
The task data itself is not encrypted on the server, but is always encrypted the moment it leaves it so all communication is protected from theft by encryption during sending and receiving, and other means during storage.