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From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: Ken Goldman <kgold@linux.ibm.com>,
	Eric Biggers <ebiggers@kernel.org>,
	Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Cc: herbert@gondor.apana.org.au, davem@davemloft.net,
	zohar@linux.ibm.com, dmitry.kasatkin@gmail.com,
	jmorris@namei.org, serge@hallyn.com,
	linux-crypto@vger.kernel.org, linux-integrity@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] crypto: sm3 - add a new alias name sm3-256
Date: Mon, 10 Feb 2020 08:39:37 -0800
Message-ID: <1581352777.3526.17.camel@HansenPartnership.com> (raw)
In-Reply-To: <1a623251-e83a-3b70-9fbd-8e929a23f7d8@linux.ibm.com>

On Mon, 2020-02-10 at 11:30 -0500, Ken Goldman wrote:
> On 2/9/2020 10:17 PM, Eric Biggers wrote:
> > According to https://tools.ietf.org/id/draft-oscca-cfrg-sm3-01.html
> > ,
> > SM3 always produces a 256-bit hash value.  E.g., it says:
> > 
> > 	"SM3 produces an output hash value of 256 bits long"
> > 
> > and
> > 
> > 	"SM3 is a hash function that generates a 256-bit hash value."
> > 
> > I don't see any mention of "SM3-256".
> > 
> > So why not just keep it as "sm3" and change hash_info.c instead?
> > Since the name there is currently wrong, no one can be using it
> > yet.
> 
> Question:  Is 256 bits fundamental to SM3?

No.

>   Could there ever be a 
> variant in the future that's e.g., 512 bits?

Yes, SM3 like SHA-3 is based on a 512  bit input blocks.  However,
what's left of the standard:

https://www.ietf.org/archive/id/draft-sca-cfrg-sm3-02.txt

Currently only defines a 256 output (via compression from the final 512
bit output).  In theory, like SHA-3, SM3 could support 384 and 512
output variants.  However, there's no evidence anyone is working on
adding this.

James


  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-07  9:22 [PATCH] IMA hash algorithm supports sm3-256 Tianjia Zhang
2020-02-07  9:22 ` [PATCH 1/2] crypto: sm3 - add a new alias name sm3-256 Tianjia Zhang
2020-02-10  3:17   ` Eric Biggers
     [not found]     ` <b7ce247b-ede1-4b01-bb11-894c042679e1.tianjia.zhang@linux.alibaba.com>
2020-02-10 12:06       ` 回复:[PATCH " Tianjia Zhang
2020-02-10 16:30     ` [PATCH " Ken Goldman
2020-02-10 16:39       ` James Bottomley [this message]
     [not found]       ` <7a496bb15f264eab920bf081338d67af@MN2PR20MB2973.namprd20.prod.outlook.com>
2020-02-10 17:01         ` Van Leeuwen, Pascal
2020-02-10 17:39           ` Mimi Zohar
2020-02-10 18:02           ` Ken Goldman
2020-02-10 18:36             ` Eric Biggers
     [not found]           ` <3b21122352a44cb9a20030a32f07e38a@MN2PR20MB2973.namprd20.prod.outlook.com>
2020-02-11  7:56             ` Van Leeuwen, Pascal
2020-02-07  9:22 ` [PATCH 2/2] ima: add sm3-256 algorithm to hash algorithm configuration list Tianjia Zhang

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