These are useful for plain devices as they don't have any metadata by themselves. Instead of using an unreliable hardcoded device name in crypttab you can then put static metadata at the start of the partition for a stable UUID or label.
https://bugs.freedesktop.org/show_bug.cgi?id=87717 https://bugs.debian.org/751707 https://launchpad.net/bugs/953875
4eac277 cryptsetup: Implement offset and skip options
man/crypttab.xml | 24 ++++++++++++++++++++++++
src/cryptsetup/cryptsetup.c | 31 ++++++++++++++++++++++++++++---
2 files changed, 52 insertions(+), 3 deletions(-)
Upstream: github.com