Securing my Time Machine back-up

[tekno]

If someone steals my laptop, they'll need my password to log-in and see any of my sensitive documents.

If someone steals my external hard drive, what's stopping them looking through my TM back-up or even simply restoring a Mac with all my files?

 

[aristobrat]

If you don't enable the option to encrypt your Time Machine backup, nothing is stopping them AFAIK.

 

[Weaselboy]

If someone steals my laptop, they'll need my password to log-in and see any of my sensitive documents.

If someone steals my external hard drive, what's stopping them looking through my TM back-up or even simply restoring a Mac with all my files?

Starting with Lion you can encrypt a Time Machine backup to a locally attached drive. You will see the setting in the Time Machine pane in System Prefs. Mountain Lion added the ability to encrypt networked backups like to a Time Capsule.

Also, the login password you mentioned is on its own not very secure. You should enable an EFI password to prevent your admin password from being reset and also enable Filevault2 encryption if you are concerned about the theft of data from a stolen laptop.