Backup disk image isn't encrypted
 

I'm backing up my hard drive into a disk image on another drive, using SuperDuper. I thought I had set it to be an encrypted image, but it doesn't seem to be. I can open it in the Finder by just clicking on it. It also mounts if I launch SuperDuper, again without entering a password.

I checked Keychain and it doesn't seem to have stored a password, so apparently there's no password protection.

Can I change this one so it's encryted and password-protected, or do I just have to start over and make a new image?

If you're comfortable with Terminal and the command line, you can use hdiutil to convert the sparse image to an encrpted on: see

for details. SD! doesn't create encrypted images internally -- you'd have to create one with Disk Utility and point us at it.

Note, though: if the password is in the keychain, it would open, and you might not be finding the right entry. Try creating a 'guest' account and opening it from there to see if it opens without a password.

I did check the Keychain.

If I make an encrypted image and back up my hard drive onto it, will it still be bootable?

No, no disk images (as opposed to directly-written backups) are bootable until restored to a real drive.

That's odd, I could swear I've booted off of a disk-image that I made on an external drive using SuperDuper. I'll have to double-check.

You definitely can't boot from an image (e.g. DMG or Sparse Image): they're not actual drives, and aren't even open at boot time.