Look into /etc/crypttab file, it should have the path to the key afaik
Make sure you have a good backup and be careful in the Debian partitioner. Unless they have changed something recently, rather than unlocking and using the current encrypted drive like most other distros, it will ask you for your key and then re-encrypt the drive (clearing data). It does this prior to confirming any partition changes. Ubuntu has done the same in my experience.
Every time I have tried to keep data I had to do some manual stuff. Fedora, SUSE, most others are happy to unlock it.
The encryption key is stored in the luks header on the disk and the phrase or key to open the encryption key can be entered at boot or after via the keyboard or from a file (usually a usb drive). So long as the luks header and encrypted data are not damaged and so long as you have the phrase or key that opens the encryption key it should survive the move. Take a dd backup of the disk just in case.
You have nothing to do if you have the keys already. But, a backup can always be welcome if things go south
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.
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