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From: Ignat Korchagin <ignat@cloudflare.com>
Date: Tue, 14 May 2024 16:38:55 +0100
Message-ID: <CALrw=nE-t6ZWCvPm=3XS_=-UM9D=mMaXL2GOw-QL5GOLtbcHmA@mail.gmail.com>
Subject: Re: [RFC PATCH 0/2] TPM derived keys
To: James Bottomley <James.Bottomley@hansenpartnership.com>
Cc: Jarkko Sakkinen <jarkko@kernel.org>, Mimi Zohar <zohar@linux.ibm.com>, 
	David Howells <dhowells@redhat.com>, Paul Moore <paul@paul-moore.com>, 
	James Morris <jmorris@namei.org>, serge@hallyn.com, linux-integrity@vger.kernel.org, 
	keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, 
	kernel-team@cloudflare.com
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On Tue, May 14, 2024 at 4:30=E2=80=AFPM James Bottomley
<James.Bottomley@hansenpartnership.com> wrote:
>
> On Tue, 2024-05-14 at 14:11 +0100, Ignat Korchagin wrote:
> >   * if someone steals one of the disks - we don't want them to see it
> > has encrypted data (no LUKS header)
>
> What is the use case that makes this important?  In usual operation
> over the network, the fact that we're setting up encryption is easily
> identifiable to any packet sniffer (DHE key exchanges are fairly easy
> to fingerprint), but security relies on the fact that even knowing that
> we're setting up encryption, the attacker can't gain access to it.  The
> fact that we are setting up encryption isn't seen as a useful thing to
> conceal, so why is it important for your encrypted disk use case?

In some "jurisdictions" authorities can demand that you decrypt the
data for them for "reasons". On the other hand if they can't prove
there is a ciphertext in the first place - it makes their case harder.

> James
>