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Date:      Wed, 14 Jan 2015 20:42:47 +0100
From:      Adam Nowacki <nowakpl@platinum.linux.pl>
To:        'freebsd-geom' <freebsd-geom@freebsd.org>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: ChaCha8/12/20 and GEOM ELI tests
Message-ID:  <54B6C6B7.4070407@platinum.linux.pl>
In-Reply-To: <54b6b91b.2aa3700a.3a6c.47b5@mx.google.com>
References:  <54b33bfa.e31b980a.3e5d.ffffc823@mx.google.com> <54B4AE55.9090205@platinum.linux.pl> <54b5d299.4914980a.61cd.43a6@mx.google.com> <20150114041708.GA3189@reks> <54b601ec.0515980a.0c9c.47e1@mx.google.com> <20150114082019.GA3669@reks> <54b6ae4c.0905990a.6c9c.642e@mx.google.com> <CAHsZcQH1BTz0Yn%2BxsRFjBxizOLaR=40Rh%2B_3TEmt6Q2mALTOog@mail.gmail.com> <54b6b91b.2aa3700a.3a6c.47b5@mx.google.com>

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On 2015-01-14 19:44, rozhuk.im@gmail.com wrote:
>> Excuse me, but if you think your physical medium is either 100%
>> inaccessible to an adversary, or simply not worth a real attack, and
>> the speed is the concern, then why do you want to use any encryption at
>> all?
> 
> 100% is not available yet introduced GELI keys / mounted drive.
> AES-XTS is good but too slow.

FreeBSD supports AES-NI - hardware accelerated AES available in many
Intel and AMD processors. I'm seeing speeds of 1GB/s on i5 2500K.

> ChaCha is already enough to cryptography was not a bottleneck.
> 
> The case when the disks - local (SATA/SAS/IDE/USB), keys entered / disk is mounted and the attacker has access I do not see because AES-XTS does not help.

A few scenarios that will break ChaCha encryption:
- remapped bad sectors on spinning disks,
- multiple copies of sectors on SSD due to wear leveling,
- RAID with one of the drives dropping out due to bad cabling, bad
sectors or other issues,
- disk imaged at multiple points in time (for example powered-off laptop
left unattended).




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