luks encryption master key file

[paige...@gmail.com]

Hello,
I'm trying to reset my luks passphrase using the master key file in the OS per these suggestions: http://unix.stackexchange.com/questions/161915/change-password-on-a-luks-filesystem-without-knowing-the-password
and
http://www.thegeekstuff.com/2016/03/cryptsetup-lukskey/

Unfortunately I installed Qubes last night in a not-so-awake state and forgot the passphrase I used but fortunately have not turned off the computer yet so I still have access to the master key file.

The instructions from the first link gave me permission failures and ended with "Cannot read keyfile /dev/fd/63". The instructions from the second link gave me no permission failures and only the response above. That file doesn't exist, though other files exist in that folder. The internet doesn't have much to say about that type of response so I'm wondering if this is a qubes specific issue.

Would rather not reinstall since I did a lot of configuration today but it's not the end of the world if I must.

Thanks in advance!

[Marek Marczykowski-Górecki]

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Did you run that commands as root?
You can do that in two steps:
1. Extract master key:
dmsetup table --showkeys $volume_name | awk '{ print $5 }' | xxd -r -p >
/tmp/master-key
2. Use it to reset password:
cryptsetup luksAddKey $device --master-key-file /tmp/master-key

Of course you need to set volume_name and device variables first (as explained in
that stackexchange answer.

- --
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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[paige...@gmail.com]

Hey Marek, thanks for the response. I did run as root for all my attempts. Your suggestion seems similar to what the second link recommends but it actually works! Not sure why it was looking for the file I referenced in the other attempts.

Anyways, I appreciate your help! And I'm very much enjoying Qubes other than this little mishap I put myself through. :)
Cheers!