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From: Chris Murphy <lists@colorremedies.com>
Date: Tue, 15 Mar 2022 10:45:23 -0600
Message-ID: <CAJCQCtSRe-nip3a6m+hzccXMYyKTP3AzPmAbHgnVPFJPLbdfCA@mail.gmail.com>
Subject: Bitlocker resize
To: cryptsetup@lists.linux.dev
Content-Type: text/plain; charset="UTF-8"

Hi,

I'm curious how Linux distro installers should go about supporting the
increasingly common case of Bitlocker enabled by default.

Is the Bitlocker format similar to LUKS in that the ciphertext volume
size is inferred from the underlying partition size?

I see in bitlkDump results of a Bitlocker volume there's no apparent
reference to its size so I'm thinking it might be conceptually the
same as LUKS, in which case the installer workflow would be the same
as LUKS. I know that cryptsetup doesn't support modifying a Bitlocker
header, but maybe it's not necessary?

pseudocode:
cryptsetup open /dev/ $name
ntfsresize --size $size /dev/mapper/$name
cryptsetup close $name
libfdisk/parted (resize the partition, create a new one in free space, etc)

Thanks,

-- 
Chris Murphy