Re: Password hash as LUKS key

[Martin Olsson <martinolsson311@yahoo.com>]

On Wed, Mar 15, 2023 at 08:35:05PM +0000, Michael Kj�rling wrote:
> Aside from that already mentioned by Grzegorz Szymaszek, a more
> general question: what leads you to believe that you can give the
> output from mkpasswd (which at least on Debian is provided by the
> "whois" package) to cryptsetup (provided by the "cryptsetup-bin"
> package) and have the mkpasswd output be recognized by cryptsetup as
> being somehow special?

> A quick web search for the two didn't reveal anything obvious
> connecting the two; and the cryptsetup man page does not mention
> mkpasswd.

Oh, I was pretty certain that it wasn't going to work since like you
said it isn't documented anywhere. So I just assumed it wasn't supported
but then Arno replied:

>In priciple,
>this works and is supported, but interactive, pipe and
>read-from-file are all a bit different.

So I decided to give it another try. But I'm pretty sure now that Arno
misunderstood what I wanted to accomplish.

I want to encrypt the password before piping it to cryptsetup.
mkpasswd was just an example of that operation. You can also use python
for example:

python3 -c 'import crypt,getpass; print(crypt.crypt(getpass.getpass(), crypt.mksalt(crypt.METHOD_SHA512)))

But as you pointed out there is nothing in cryptsetup that recognizes
the encrypted string as anything other than a normal password. I was
hoping there was an option somewhere that I could add as an argument
to my cryptsetup command.

As there is no such option I am wondering if there is another solution
to my use case:

"I want to encrypt a drive for a user and I don't want the user to send me
their password in clear text."