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How to use an external hard drive on Mac AND PC + encrypt it?


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#1 chooza97

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Posted 08 July 2014 - 01:06 PM

Hi all, thanks for any responses in advance. 

 

I have a 1 TB external hard drive that I need to be able to use on both Mac and PC computers. Additionally, I need to be able to encrypt it with a password. The issue that I'm having is combining these two needs. Currently I have the drive formatted to exFAT (to use on both operating systems) but I am unable to encrypt using Disk Utility, as I get the message "A GUID Partition Table (GPT) partitioning scheme is required."

 

When I try to repartition, I get "You can't resize the partitions on this disk because it uses the Master Boot Partition scheme." 

 

How can I get past this? Ideally, I would not like to download any additional software and use Disk Utility, but I don't know how to get past the error messages.

 

There is nothing on the drive I need so I am prepared to wipe the HD if required. 

 

Thanks, 

 

Chooza97


Edited by chooza97, 08 July 2014 - 01:08 PM.


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#2 JohnC_21

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Posted 08 July 2014 - 01:50 PM

If you have a MAC format to exFAT but under Options select GUID partition scheme.

 

http://forums.macrumors.com/showpost.php?p=12483448&postcount=22



#3 chooza97

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Posted 08 July 2014 - 04:29 PM

Thanks, I was able to select GUID. However, when I tried to encrypt one of the two partitions I created by right-clicking, choosing encrypt and entering a password, I was given the error message "The given file system is not supported on core storage." 

 

So still unable to encrypt.



#4 JohnC_21

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Posted 08 July 2014 - 05:15 PM

I don't know what encryption program you are using but it seems it does not support exFAT. The disk encryption program is part of the MAC OS Disk Utility? How would you decrypt if the external was on a PC and not a MAC?

#5 Kilroy

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Posted 08 July 2014 - 05:58 PM

I've never done this, but have received a fully encrypted drive from a data recovery company.  This process using True Crypt should work, provided you use a format for the drive that can be read by both operating systems.



#6 green_orange

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Posted 08 July 2014 - 08:44 PM

This process using True Crypt should work, provided you use a format for the drive that can be read by both operating systems.

I second that, only if there is no other way (which seems to be the situation here).

 

That's because the official truecrypt site says now:

 

 

WARNING: Using TrueCrypt is not secure

You should download TrueCrypt only if you are migrating data encrypted by TrueCrypt.

 



#7 chooza97

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Posted 09 July 2014 - 10:58 AM

JohnC_21, I suppose I wouldn't, because I am unable to encrypt the hard drive in the first place. I wasn't using Disk Utility TO encrypt persay; I was just right-clicking on the drive on my desktop and choosing "encrypt". Whether that process uses Disk Utility I don't know. 

 

This drive is going to have very sensitive data on it (patient records and the like) so I don't think using TrueCrypt is the best option for me if it isn't secure. The drive has to be secure. Does anyone have any other solutions? (Desperate plea for help here)



#8 JohnC_21

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Posted 09 July 2014 - 11:33 AM

Truecrypt has been undergoing an audit and so far, a backdoor has not been found. There has been a lot of speculation on why the developers said Truecrypt was no longer secure. See this. If you do decide to use Truecyrpt download version 7.1a at the grc site and create a container instead of encrypting the full partition. You can use multiple encryption schemes.

 

https://www.calyxinstitute.org/education/howto-encrypting-documents-and-files-on-osx-with-truecrypt

 

http://www.ecu.edu/cs-itcs/mac/TrueCrypt-Making-it-Portable.cfm

 

Mac's can use filevault.s

 

Edit: Truecrypt cannot be uses on a GPT disk or Diskcryptor for that matter.


Edited by JohnC_21, 09 July 2014 - 11:35 AM.


#9 chooza97

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Posted 10 July 2014 - 03:29 PM

I'm the polar opposite of tech savvy so sorry if this comes across as a stupid question but does your edit  "Truecrypt cannot be uses on a GPT disk or Diskcryptor for that matter" mean that I should disregard the rest of your post because it is no longer relevant to me? (i.e. Do I have a "GPT disk" - whatever that is - on my hands and thus should not try and use TrueCrypt?)



#10 JohnC_21

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Posted 10 July 2014 - 03:38 PM

In your first post,  you wanted to encrypt the drive but it stated you needed a GPT disk to do it. You formatted to exFAT and created a GPT partition scheme using a MAC I assume from post #3. If you are planning to use Truecypt, then you have to use a MBR partition scheme. Truecyrpt will not work on a GPT disk. Diskcryptor is an alternative to Truecrypt but there is no MAC version as far as I know. It also cannot be used on a GPT disk. If you are going to encrypt and decrypt on a MAC, you may be better off using MAC's own Filevault that I linked to. I do not know if Filevault uses a GPT or MBR partition scheme.



#11 chooza97

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Posted 11 July 2014 - 03:11 PM

Ah, I see. Thanks for bearing with me. I suppose the only solution is to go back to the MBR partition scheme and use TrueCrypt. 

 

Unless... I download Diskcryptor on a PC, encrypt the disk on a PC, and use the disk on both PC and Mac. Is that possible?



#12 JohnC_21

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Posted 11 July 2014 - 05:06 PM

That is correct. Diskcryptor also has to be installed on the computer you are using to encrypt and decrypt. There is no portable mode with containers as Truecyrpt has. If you had the drivers of Truecrypt on the external hard drive that had the encrypted container, you would be able to decrypt the container on any computer as long as you had admin rights. So basically with Truecrypt you could have one partition on the external drive with the encrypted container.

 

It's also best to backup the data unencrypted and store it in an offsite location like a safety deposit box. One nice thing about Diskcryptor is the ability to use keyfiles in addition to your password. This makes is doubly difficult to hack. But, you need to make backups of the keyfiles because if they become corrupted you would not longer be able to decrypt the partition. With Diskcryptor you can also back up the partition header for recovery. So for your situation the external hard drive would have two partitons, one unencrypted and the other encrypted. Do not make the mistake of encrypting your system partition when setting up Diskcryptor.

 

Here are some helpful links on Diskcryptor.

 

http://www.ghacks.net/2014/06/06/five-tips-disk-encryption-software-diskcryptor/

 

http://www.ghacks.net/2012/08/08/how-to-encrypt-partitions-with-diskcryptor/



#13 chooza97

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Posted 17 July 2014 - 09:33 AM

Sorry, I've been out of town for a few days and unable to check the forum. 

 

Wait... but if Diskcryptor has to be installed on the computer I am using to encrypt and decrypt, and there is no MAC version of it, then doesn't it follow that I wouldn't be able to use it on both my Mac and PC? (This of course based on the assumption that every time I plug it in I would need to decrypt it to view and add files.) 



#14 JohnC_21

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Posted 17 July 2014 - 09:52 AM

That is correct, if using Diskcryptor, you would only be able to decrypt on a PC with Diskcryptor installed. I am not sure if you could encrypt or decrypt between a PC and MAC if you use Truecrypt because I believe the drivers between the PC and MAC would not be compatible. You have to decide which OS you want to emcrypt and decrypt on and install that version.




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