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From: Nikolay Borisov <nborisov@suse.com>
To: Paul Jones <paul@pauljones.id.au>,
	"dsterba@suse.cz" <dsterba@suse.cz>,
	Johannes Thumshirn <jthumshirn@suse.de>
Cc: David Sterba <dsterba@suse.com>,
	Linux BTRFS Mailinglist <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH 00/17] Add support for SHA-256 checksums
Date: Thu, 16 May 2019 11:16:38 +0300	[thread overview]
Message-ID: <4db81b36-a2ac-f954-abad-f020e42120ca@suse.com> (raw)
In-Reply-To: <SYCPR01MB5086D225BE48AD0AD9BBA4B69E0A0@SYCPR01MB5086.ausprd01.prod.outlook.com>



On 16.05.19 г. 9:30 ч., Paul Jones wrote:
> 
>> -----Original Message-----
>> From: linux-btrfs-owner@vger.kernel.org <linux-btrfs-
>> owner@vger.kernel.org> On Behalf Of David Sterba
>> Sent: Thursday, 16 May 2019 3:27 AM
>> To: Johannes Thumshirn <jthumshirn@suse.de>
>> Cc: David Sterba <dsterba@suse.com>; Linux BTRFS Mailinglist <linux-
>> btrfs@vger.kernel.org>
>> Subject: Re: [PATCH 00/17] Add support for SHA-256 checksums
>>
>>
>> Once the code is ready for more checksum algos, we'll pick candidates and
>> my idea is to select 1 fast (not necessarily strong, but better than crc32c) and
>> 1 strong (but slow, and sha256 is the candidate at the moment).
>>
>> The discussion from 2014 on that topic brought a lot of useful information,
>> though some algos have could have evolved since.
>>
>> https://lore.kernel.org/linux-btrfs/1416806586-18050-1-git-send-email-
>> bo.li.liu@oracle.com/
>>
>> In about 5 years timeframe we can revisit the algos and potentially add more,
>> so I hope we'll be able to agree to add just 2 in this round.
>>
>> The minimum selection criteria for a digest algorithm:
>>
>> - is provided by linux kernel crypto subsystem
>> - has a license that will allow to use it in bootloader code (grub at
>>   lest)
>> - the implementation is available for btrfs-progs either as some small
>>   library or can be used directly as a .c file
> 
> 
> Xxhash would be a good candidate. It's extremely fast and almost crypto secure.  Has been in the kernel for ~2 yeas iirc.

Disclaimer: not a cryptographer. But according to the official site:
xxHash is non-cryptography hash. From the (draft) spec:

It is labelled non-cryptographic, and is not meant to avoid intentional
collisions (same digest for 2 different messages), or to prevent
producing a message with predefined digest.

This doesn't disqualify it, however we need to be aware its limitations.
Perhahps it could be used as a replacement for crc32c but definitely not
as secure crypto hash.

> 
> 
> Paul.
> 

  reply	other threads:[~2019-05-16  8:16 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-10 11:15 [PATCH 00/17] Add support for SHA-256 checksums Johannes Thumshirn
2019-05-10 11:15 ` [PATCH 01/17] btrfs: use btrfs_csum_data() instead of directly calling crc32c Johannes Thumshirn
2019-05-10 16:16   ` Nikolay Borisov
2019-05-10 11:15 ` [PATCH 02/17] btrfs: resurrect btrfs_crc32c() Johannes Thumshirn
2019-05-10 16:16   ` Nikolay Borisov
2019-05-10 11:15 ` [PATCH 03/17] btrfs: use btrfs_crc32c() instead of btrfs_extref_hash() Johannes Thumshirn
2019-05-10 13:03   ` Nikolay Borisov
2019-05-10 11:15 ` [PATCH 04/17] btrfs: use btrfs_crc32c() instead of btrfs_name_hash() Johannes Thumshirn
2019-05-10 12:56   ` Chris Mason
2019-05-13  7:04     ` Johannes Thumshirn
2019-05-10 11:15 ` [PATCH 05/17] btrfs: don't assume ordered sums to be 4 bytes Johannes Thumshirn
2019-05-10 13:25   ` Nikolay Borisov
2019-05-10 13:27     ` Nikolay Borisov
2019-05-13  7:06       ` Johannes Thumshirn
2019-05-10 11:15 ` [PATCH 06/17] btrfs: dont assume compressed_bio " Johannes Thumshirn
2019-05-10 11:15 ` [PATCH 07/17] btrfs: use btrfs_crc32c{,_final}() in for free space cache Johannes Thumshirn
2019-05-10 13:27   ` Nikolay Borisov
2019-05-10 11:15 ` [PATCH 08/17] btrfs: format checksums according to type for printing Johannes Thumshirn
2019-05-10 13:28   ` Nikolay Borisov
2019-05-10 11:15 ` [PATCH 09/17] btrfs: add common checksum type validation Johannes Thumshirn
2019-05-10 13:37   ` Nikolay Borisov
2019-05-10 11:15 ` [PATCH 10/17] btrfs: check for supported superblock checksum type before checksum validation Johannes Thumshirn
2019-05-10 13:37   ` Nikolay Borisov
2019-05-10 11:15 ` [PATCH 11/17] btrfs: Simplify btrfs_check_super_csum() and get rid of size assumptions Johannes Thumshirn
2019-05-10 13:41   ` Nikolay Borisov
2019-05-10 11:15 ` [PATCH 12/17] btrfs: add boilerplate code for directly including the crypto framework Johannes Thumshirn
2019-05-10 16:28   ` Nikolay Borisov
2019-05-10 11:15 ` [PATCH 13/17] btrfs: pass in an fs_info to btrfs_csum_{data,final}() Johannes Thumshirn
2019-05-10 11:15 ` [PATCH 14/17] btrfs: directly call into crypto framework for checsumming Johannes Thumshirn
2019-05-10 13:45   ` Chris Mason
2019-05-10 13:54     ` Chris Mason
2019-05-13  7:17       ` Johannes Thumshirn
2019-05-13 13:55         ` Chris Mason
2019-05-14 12:46     ` Johannes Thumshirn
2019-05-13 13:00   ` David Sterba
2019-05-13 13:01     ` Johannes Thumshirn
2019-05-13 14:30       ` David Sterba
2019-05-10 11:15 ` [PATCH 15/17] btrfs: remove assumption about csum type form btrfs_csum_{data,final}() Johannes Thumshirn
2019-05-13 12:56   ` David Sterba
2019-05-10 11:15 ` [PATCH 16/17] btrfs: remove assumption about csum type form btrfs_print_data_csum_error() Johannes Thumshirn
2019-05-10 11:15 ` [PATCH 17/17] btrfs: add sha256 as another checksum algorithm Johannes Thumshirn
2019-05-10 12:30   ` Nikolay Borisov
2019-05-13  7:11     ` Johannes Thumshirn
2019-05-13 12:54       ` David Sterba
2019-05-13 12:55         ` Johannes Thumshirn
2019-05-15  1:45         ` Jeff Mahoney
2019-05-13 12:55     ` David Sterba
2019-05-13 12:58       ` Johannes Thumshirn
2019-05-15 17:27 ` [PATCH 00/17] Add support for SHA-256 checksums David Sterba
2019-05-16  6:30   ` Paul Jones
2019-05-16  8:16     ` Nikolay Borisov [this message]
2019-05-16  8:20       ` Johannes Thumshirn
2019-05-17 18:36   ` Diego Calleja
2019-05-17 19:07     ` Johannes Thumshirn
2019-05-18  0:38       ` Adam Borowski
2019-05-20  7:47         ` Johannes Thumshirn
2019-05-20 11:34           ` Austin S. Hemmelgarn
2019-05-20 11:57             ` Johannes Thumshirn
2019-05-20 11:42     ` Austin S. Hemmelgarn
2019-05-30 12:21     ` David Sterba

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