How do I backup OpeBSD FDE header?

uxer

This has already been asked on the mailing list.

A question without any replies:
https://marc.info/?l=openbsd-misc&m=145651555632472&w=2

Three replies to another question without an actual answer:
https://marc.info/?l=openbsd-misc&m=167289127525804&w=2
https://marc.info/?l=openbsd-misc&m=167289575727338&w=2
https://marc.info/?l=openbsd-misc&m=167292745710871&w=2

As if nobody on the mailing list understands how OpenBSD FDE works and where it puts its header and how to read and write that piece!

I would expect it to be stored in a well-known place and be readable, erasable and restorable with dd...

uxer

Stumbled upon a partial answer:
https://marc.info/?l=openbsd-misc&m=167291329902704&w=2

Look at /usr/src/sys/dev/softraidvar.h.

The structures that contain the softraid metadata are defined there. There is
general softraid metadata, and crypto specific metadata.

These are stored near the beginning of the RAID partition as defined in the
disklabel. In fact, they are SR_META_OFFSET blocks from the start, which is
currently 8192 bytes.

No reports on practical application though