Open a LUKS container storing the operating system, with a header file in another location

[21naown@gmail.com]

Hello,


I would like to open a LUKS container (which is the OS Debian) through 
GRUB, but with the header stored in a USB key for example. Through the 
file crypttab 
(https://manpages.debian.org/stretch/cryptsetup/crypttab.5.en.html), it 
seems possible to specify the path of the header, but I have different 
failures and I do not know where the problem is.

Do you have an example, especially of a header path which works outside 
of the OS? (ArchLinux provides some fragments of examples, but it does 
not seem to work with Debian; other sites do not help either, and I 
would sincerely like to avoid using scripts in initrd/initramfs)


Thank you for your understanding.

Best regards.