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From: Eric Biggers <ebiggers@kernel.org>
To: "Dey, Megha" <megha.dey@intel.com>
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	ravi.v.shankar@intel.com, tim.c.chen@intel.com,
	andi.kleen@intel.com, dave.hansen@intel.com,
	wajdi.k.feghali@intel.com, greg.b.tucker@intel.com,
	robert.a.kasten@intel.com, rajendrakumar.chinnaiyan@intel.com,
	tomasz.kantecki@intel.com, ryan.d.saffores@intel.com,
	ilya.albrekht@intel.com, kyung.min.park@intel.com,
	Tony Luck <tony.luck@intel.com>,
	ira.weiny@intel.com
Subject: Re: [RFC V1 3/7] crypto: ghash - Optimized GHASH computations
Date: Fri, 15 Jan 2021 17:43:23 -0800	[thread overview]
Message-ID: <YAJEu1esw0zPA7Qh@gmail.com> (raw)
In-Reply-To: <dfb5f2e0-027d-2b9c-aec7-313ff0275381@intel.com>

On Fri, Jan 15, 2021 at 04:14:40PM -0800, Dey, Megha wrote:
> > Hello Megha,
> > 
> > What is the purpose of this separate GHASH module? GHASH is only used
> > in combination with AES-CTR to produce GCM, and this series already
> > contains a GCM driver.
> > 
> > Do cores exist that implement PCLMULQDQ but not AES-NI?
> > 
> > If not, I think we should be able to drop this patch (and remove the
> > existing PCLMULQDQ GHASH driver as well)
> 
> AFAIK, dm-verity (authenticated but not encrypted file system) is one use
> case for authentication only.
> 
> Although I am not sure if GHASH is specifically used for this or SHA?
> 
> Also, I do not know of any cores that implement PCLMULQDQ and not AES-NI.
> 

dm-verity only uses unkeyed hash algorithms.  So no, it doesn't use GHASH.

- Eric

  parent reply	other threads:[~2021-01-16  1:44 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-18 21:10 [RFC V1 0/7] Introduce AVX512 optimized crypto algorithms Megha Dey
2020-12-18 21:10 ` [RFC V1 1/7] x86: Probe assembler capabilities for VAES and VPLCMULQDQ support Megha Dey
2021-01-16 16:54   ` Ard Biesheuvel
2021-01-20 22:38     ` Dey, Megha
2020-12-18 21:10 ` [RFC V1 2/7] crypto: crct10dif - Accelerated CRC T10 DIF with vectorized instruction Megha Dey
2021-01-16 17:00   ` Ard Biesheuvel
2021-01-20 22:46     ` Dey, Megha
2020-12-18 21:11 ` [RFC V1 3/7] crypto: ghash - Optimized GHASH computations Megha Dey
2020-12-19 17:03   ` Ard Biesheuvel
2021-01-16  0:14     ` Dey, Megha
2021-01-16  0:20       ` Dave Hansen
2021-01-16  2:04         ` Eric Biggers
2021-01-16  5:13           ` Dave Hansen
2021-01-16 16:48             ` Ard Biesheuvel
2021-01-16  1:43       ` Eric Biggers [this message]
2021-01-16  5:07         ` Dey, Megha
2020-12-18 21:11 ` [RFC V1 4/7] crypto: tcrypt - Add speed test for optimized " Megha Dey
2020-12-18 21:11 ` [RFC V1 5/7] crypto: aesni - AES CTR x86_64 "by16" AVX512 optimization Megha Dey
2021-01-16 17:03   ` Ard Biesheuvel
2021-01-20 22:46     ` Dey, Megha
2020-12-18 21:11 ` [RFC V1 6/7] crypto: aesni - fix coding style for if/else block Megha Dey
2020-12-18 21:11 ` [RFC V1 7/7] crypto: aesni - AVX512 version of AESNI-GCM using VPCLMULQDQ Megha Dey
2021-01-16 17:16   ` Ard Biesheuvel
2021-01-20 22:48     ` Dey, Megha
2020-12-21 23:20 ` [RFC V1 0/7] Introduce AVX512 optimized crypto algorithms Eric Biggers
2020-12-28 19:10   ` Dey, Megha
2021-01-16 16:52     ` Ard Biesheuvel
2021-01-16 18:35       ` Dey, Megha

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