August 27, 2014

How to Encrypt Your Nifty MiniDrive

I am lucky enough to have received a Nifty MiniDrive for my Retina MacBook Pro, and am in process of putting it through its paces with a SanDisk 64 GB SDXC card. One of the first concerns I had is the steal-ability of such a small, valuable, content-rich item. So I decided to protect it using Mac OS X’s FIleVault 2 full-disk encryption technology. Here’s a step-by-step guide and my post-encryption thoughts!

How to Encrypt the Nifty MiniDrive

First, it’s important to remember that you’re not really encrypting the Nifty MiniDrive at all; instead, you are encrypting the Micro SDXC card it contains. The MiniDrive is transparent to the operating system, as it contains no or logic circuits. So this same guy applies to encrypting any SDXC card!

Second, since I am using an SDXC card, some of these steps might change somewhat for plain SD cards. SDXC was designed to use the ExFAT filesystem, but they retain the same MBR partitioning scheme of previous cards. This doesn’t mean they can’t be repartitioned with GPT and reformatted with HFS+, however!

Without more fuss, here’s the steps to encrypt the SDXC card in your Nifty MiniDrive!

You have to click a lot to get Disk Utility to repartition your Nifty MiniDrive SD card correctly!

  1. First, we repartition the card with GPT and HFS+
    1. Open Disk Utility

    2. Select “Apple SDXC Reader Media”

    3. Click “Partition”

    4. Select “1 Partition” in the Partition Layout drop down

    5. Click “Options…”

    6. Select “GUID Partition Table” and click “OK”

    7. Select “Mac OS Extended (Journaled)” in the Format drop down

    8. Give it a Name

    9. Click “Apply”

    10. Click “Partition”
    11. Quit Disk Utility
  2. Now let’s tell Mac OS X to encrypt this new device
    1. Open a Finder window
    2. Find Nifty in the left side menu
    3. Option-click and select “Encrypt Nifty”
    4. Enter a strong Encryption password and hint
    5. Click “Encrypt Disk”
  3. Wait…
    1. It will unmount and remount as a CoreStorage Encrypted volume
    2. It will take a long time to encrypt – about 10 minutes per GB in my case, so 10 hours for a 64 GB card!
    3. You can use it while it’s encrypting, but then it will take even longer. Just let it go.
  4. Optionally save the password in your Keychain
    1. Once it’s done encrypting, eject the drive
    2. Re-insert it
    3. Enter your password in the dialog and select “Remember this password in my keychain”
    4. Click “Unlock”
    5. Now it’ll automatically remount whenever you insert it

You may want Mac OS X to remember the volume password for you

Watch Out! It’s SLOW!

Micro SD cards are notoriously slow, but encryption makes this even worse. Writing to an encrypted Nifty MiniDrive is absolutely ridiculously pathetically slow. It’s worst than watching paint dry. Seriously. It’s terrible.

Now that I’ve given you the subjective feeling, here are some objective numbers: Before encryption, the 64 GB SanDisk Micro SDXC card would read at a reasonable 40 MB/s but write below 6 MB/s. After encryption, I’m seeing under 2 MB/s writes. That’s floppy drive slow. It makes a USB 2.0 flash drive seem fast.

This is exacerbated by the target market for the Nifty MiniDrive: The MacBook Air and MacBook Pro with Retina are very, very fast, equipped with some of the best SSDs on the market. It’s really jarring to compare the internal SSD’s 200 MB/s or more with the MiniDrive’s 2 MB/s or less. Seriously – it’s easily 100x slower!

Reads are fine, however, even after encryption. Although 30-40 MB/s isn’t exactly speedy, it’s plenty fast for videos, office documents, etc. It’s fast enough on reads that you won’t even notice it except on big transfers.

Note that this performance issue has nothing at all to do with Nifty’s engineering of their MiniDrive. It’s a passive electrical device and does nothing to slow (or speed up) the SD card it contains. The core problem is that Micro SD cards are simple and slow and there’s no getting around that.

Stephen’s Stance

I’m pleased that it’s this easy to encrypt the Nifty MiniDrive. I recommend encrypting all portable media, and this is especially important for a highly steal-able device like this. But the speed impact is so dramatic, it limits the usefulness of the device. Caveat Encryptor!

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