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Re: Encrypted home directory



"Nikolay Vladimirov" <nikolay vladimiroff com> writes:

> 2008/12/23 Eric Christensen <eric christensenplace us>:
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>>
>> Ralf Ertzinger wrote:
>>> Hi.
>>>
>>> On Tue, 23 Dec 2008 10:30:31 +0200, Nikolay Vladimirov wrote:
>>>
>>>> Ok. I'm not really sure about this but I think that full disk
>>>> encryption on a software level
>>>> with a key storng enough will bring some performance loss. And some
>>>> people just want
>>>> some confidential files to be encrypted.
>>>
>>> I'm running full-LV encryption for /home (and some other directories) in
>>> my laptop, and the performance loss is nonexistant for me. Getting the
>>> bits off the rotating rust takes quite longer then decrypting them.
>>>
>>> After all, all the cores in that thing have to be good for something.
>>>
>>> (Core Duo, 1.6GHz)
>>>
>> I've been running full disk encryption via LUKS since F8 with a 6 year
>> old laptop.  I don't see any noticeable performance loss.
>>
>> Just to comment on the whole disk versus just a folder in the /home,
>> Windows did the same thing a number of years ago on XP (and since I
>> believe but I don't know).  You could select a folder and "encrypt" it.
>>  The crypto implementation was horrible and when people actually used it
>> they never realized that they weren't getting ALL the sensitive data
>> encrypted.  There will always be a cache or tmp file laying around in
>> the clear that will contain sensitive information.
>>
>> The DoD didn't like the use of the folder level encryption and has sense
>> mandated full disk encryption for all portable devices.  It saves the
>> user from trying to figure out what is sensitive and what needs to be
>> encrypted and breaking their storage schema just to put a specific file
>> into a specific folder.  The user will ALWAYS miss something and will
>> ALWAYS be left vulnerable.
>>
>> Thanks,
>> Eric Christensen
>>
>
> That seems reasonable. I really see two good paths to this data security thing:
> 1) Some hardware level encryption. Like in my thingpad I have some
> trusted something thingie
> and another hard drive security thing. This way there will be no
> software complications.
> 2) Encrypted /home since all of the user's sensitive data should be there.
>
>  It's good to have some notice like "Full disk encryption is more
> secure" and "Note that some cache saved outside of the /home dir may
> be visible ( swap, /tmp, stuff)" and "Using some BIOS setting stuff is
> more secure".
> Some benchmarks of encrypted stuff vs non encrypted will be nice to
> know for sure about the performance loss.
> And some info in the installation media about this stuff maybe taken
> from "Security Guide" in the wiki will be nice.
>
> Note: I'm not very competent in this whole encryption stuff. I'm just
> offering some user point of view on this.


I am using dm-crypt/LUKS on F10 and have been doing so for several
releases.

Since F9, when Anaconda began supporting encrypted partitions during
installation, as opposed to the PITA manual set up previously, I have
been using LVM to configure my disk. So '/', '/home' and swap are all
encrypted as separate partitions within the LVM group configuration.

I have a separate /boot partition outside the LVM, since that cannot be
encrypted.

Using hdparm to test sequential reads on the encrypted and unencrypted
partitions, I get 30 MB/Sec on the former and 36 MB/Sec on the latter.
So I am looking at a 15-20% hit on throughput and that has been pretty
consistent over several releases.

This is on a 4 year old Dell Inspiron laptop, with a 3.2Ghz P4 and a
7200 rpm HD.

HTH,

Marc Schwartz



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