Ubuntu 18.04 LTS

Hi, just bought a new laptop and have forgotten the LUKS password for 2 USB-128GB drive backups.

On the old laptop I have it set to auto-login to the LUKS drives on start-up and still works fine. I don't really need that actual password, but it would be handy. I am hoping I find whatever file the old one is using to auto-login and transfer that file to the new laptop.

I checked the LUKS drives and only slot-0 is being used on both. I thought I might be able to add another password since it is already accessible, but it asks for the current password. Catch-22.

The backups are about 80GB, so copying off is an option, just not a pleasant one.

Any help?

Thanks