Creating and then erasing the key relies on the disk erasing data
correctly, and otherwise allows attackers to simply decrypt swap just
using "secretkey". We don't actually need a LUKS header, so we can save
ourselves some pointless disk writes and identifiability.
In addition, I wouldn't have made the awful mistake of backing up my swap partition's LUKS header instead of my zpool's. May my data rest in peace.
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