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NNTP-Posting-Date: Mon, 12 Oct 2015 16:39:36 -0500
Subject: Re: Encrypt existing Time Machine backups?
Newsgroups: comp.sys.mac.apps,comp.sys.mac.hardware.storage,comp.sys.mac.system
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From: Alan Browne <alan.browne@freelunchvideotron.ca>
Date: Mon, 12 Oct 2015 17:39:35 -0400
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On 2015-10-12 17:32, Jolly Roger wrote:
> On 2015-10-12, John Somerset <somerset@nospam.com> wrote:
>> On 10/12/15 9:54 AM, Alan Browne wrote:
>>> On 2015-10-12 08:58, Alan Browne wrote:
>>>> On 2015-10-11 19:56, John Somerset wrote:
>>
>>>>> Oh, I thought that encrypting a disk, as with Filevault, meant the whole
>>>>> disk had to be unencrypted to work. If memory can grab only what it
>>>>> needs, that sounds much faster.
>>>
>>> Doh.  I really misread what you wrote when I replied with the stuff below.
>>>
>>> But yes, the drive remains encrypted and the data from the FileVaulted
>>> drive is decrypted in memory on your Mac as needed, file by file (or
>>> probably block by block)
>>>
>> Am I correct that if I encrypted a folder, I couldn't get at any file
>> without decrypting the whole folder?
>
> It's my understanding that with FileVault 2 full disk encryption, it is
> not folders and files, but individual *blocks* of the volume. FileVault
> encrypted disks are CoreStorage logical volume groups that work with the
> LVM built into OS X. Encryption and decryption work at the logical
> volume level rather than the file system level.

I took that question to be for a given folder encrypted into a DMG. 
Otherwise agree with what you wrote.

>
>> Correct or not, that was my concept of it.  That's why I assumed
>> Filevault needed to decrypt a disk to get access to any of it.  It
>> sounded time-consuming, with disaster always lurking.
>
> FileVault 2 in particular is extremely simple, reliable, and safe, and
> is used by millions of Apple customers daily.