From: Eric Biggers <ebiggers@kernel.org>
To: "Bae, Chang Seok" <chang.seok.bae@intel.com>
Cc: "dm-devel@redhat.com" <dm-devel@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@suse.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
Ingo Molnar <mingo@kernel.org>,
"Lutomirski, Andy" <luto@kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Herbert Xu <herbert@gondor.apana.org.au>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
"Williams, Dan J" <dan.j.williams@intel.com>,
"Gairuboyina, Charishma1" <charishma1.gairuboyina@intel.com>,
"Dwarakanath, Kumar N" <kumar.n.dwarakanath@intel.com>,
"Krishnakumar,
Lalithambika" <lalithambika.krishnakumar@intel.com>,
"Shankar, Ravi V" <ravi.v.shankar@intel.com>
Subject: Re: [PATCH v4 00/13] x86: Support Key Locker
Date: Wed, 5 Jan 2022 21:07:42 -0800 [thread overview]
Message-ID: <YdZ5HrOKEffBrQIm@sol.localdomain> (raw)
In-Reply-To: <4101B942-6327-49A9-BE8B-9E51F0427F50@intel.com>
On Wed, Jan 05, 2022 at 09:55:17PM +0000, Bae, Chang Seok wrote:
> >> +-----------+---------------+---------------+
> >> | Cipher | Encryption | Decryption |
> >> | (AES-KL) | (MiB/s) | (MiB/s) |
> >> +-----------+---------------+---------------+
> >> | AES-CBC | 505.3 | 2097.8 |
> >> | AES-XTS | 1130 | 696.4 |
> >> +-----------+-------------------------------+
> >
> > Why is AES-XTS decryption so much slower than AES-XTS encryption? They should
> > be about the same.
>
> Analyzing and understanding this with specific hardware implementation takes
> time for us. Will come back and update you when we have anything to share here.
Note that for disk encryption, decryption performance is usually more important
than encryption performance. So your performance results are strange.
> > Also, is the AES-CBC support really useful, given that for disk encryption,
> > AES-XTS is recommended over AES-CBC these days?
>
> Yes, we understand that AES-XTS is the primary option for disk encryption.
>
> But it seems that AES-CBC had been used for disk encryption, [1]:
>
> Comparing XTS to CBC for hard disk encryption
> If a storage device vendor is seeking FIPS 140-2 certification today,
> they will typically use CBC encryption, or even ECB. CBC is a good
> mode, ...
That document is very old. XTS has been NIST-approved for over a decade now.
>
> As long as it is factual that the mode was once popular, it can help somebody
> who wants to use Key Locker for an old disk image I think.
AES-CBC is/was usually used with ESSIV, in which case the key cannot be fully
protected by Key Locker.
I'm not sure you should bother to support legacy use cases, especially since it
might mislead users into choosing a worse algorithm.
- Eric
next prev parent reply other threads:[~2022-01-06 5:07 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-14 0:51 [PATCH v4 00/13] x86: Support Key Locker Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 01/13] Documentation/x86: Document " Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 02/13] x86/cpufeature: Enumerate Key Locker feature Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 03/13] x86/insn: Add Key Locker instructions to the opcode map Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 04/13] x86/asm: Add a wrapper function for the LOADIWKEY instruction Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 05/13] x86/msr-index: Add MSRs for Key Locker internal wrapping key Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 06/13] x86/keylocker: Define Key Locker CPUID leaf Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 07/13] x86/cpu/keylocker: Load an internal wrapping key at boot-time Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 08/13] x86/power/keylocker: Restore internal wrapping key from the ACPI S3/4 sleep states Chang S. Bae
2021-12-17 15:42 ` Rafael J. Wysocki
2021-12-22 4:58 ` Bae, Chang Seok
2021-12-14 0:52 ` [PATCH v4 09/13] x86/cpu: Add a configuration and command line option for Key Locker Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 10/13] crypto: x86/aes - Prepare for a new AES implementation Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 11/13] crypto: x86/aes-kl - Support AES algorithm using Key Locker instructions Chang S. Bae
2021-12-24 17:42 ` Andy Lutomirski
2022-01-07 18:06 ` Bae, Chang Seok
2021-12-14 0:52 ` [PATCH v4 12/13] crypto: x86/aes-kl - Support CBC mode Chang S. Bae
2021-12-14 0:52 ` [PATCH v4 13/13] crypto: x86/aes-kl - Support XTS mode Chang S. Bae
2021-12-16 1:09 ` [PATCH v4 00/13] x86: Support Key Locker Eric Biggers
2022-01-05 21:55 ` Bae, Chang Seok
2022-01-06 5:07 ` Eric Biggers [this message]
2022-01-06 6:13 ` Bae, Chang Seok
2022-01-06 16:25 ` [dm-devel] " Milan Broz
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