SSDs with usable built-in hardware-based full disk encryption

(tl;dr / post summary: Many current SSDs do super fast hardware AES encryption, but only a very few expose this correctly to the user, meaning you often still need a third-party software solution. Information on this is incredibly hard to find.)

Imagine that your laptop or your PC gets stolen. That would be terrible. However, it would be even worse if your laptop contained confidential data, either your own or that of your employer or client. It’s clear that encrypting one’s hard drive has become a necessity. There are good open source software solutions for this, for example TrueCrypt (Windows, Linux and OSX) and the LUKS/dm-crypt system. However, such software encryption systems require a small chunk of your CPU capacity, and also affect SSD performance and durability to a lesser or greater extent, depending on the controller.

Intel 520 self-encrypting SSD. Image courtesy of Anand Tech.
Intel 520 self-encrypting SSD. Image courtesy of Anand Tech.

A number of SSD drives now implement real-time AES encryption in hardware. Usually the reason for this is to enable fast secure erase: When the AES keys are destroyed by the firmware, a very cheap operation that requires almost no writing to the flash, no data on the whole SSD can be read, and can thus the data can be considered securely erased. The encryption and decryption take place in the controller hardware, so there is no performance hit. The Sandforce SF2281 controller is one of the more well-known SSD controllers that does this. In some cases, the manufacterer uses the HDD password or ATA password (configurable via many laptop BIOSes, very few desktop BIOSes, or the ATASX BIOS extension) to encrypt the AES keys. This means that even if the manufacturer got hold of your drive, and you had set a strong ATA password, they would probably never be able to decrypt your data. I call this usable built-in-hardware-based full disk encryption. In these cases, you do NOT need to install third-party software full disk encryption, and can enjoy the full performance of your SSD. In many other cases, the encryption keys are stored in the drive firmware, but are NOT explicitly encrypted with a user-supplied password. This is non-usable encryption, because in theory the manufacturer or a sufficiently skilled hardware hacker can extract the encryption keys from the drive firmware and decrypt all of your data. In these cases, you ABSOLUTELY have to use a third-party software disk encryption software tool. The purpose of this post is to keep a list of current SSDs with usable and non-usable built-in hardware-based full disk encryption. Whilst recently shopping for a suitable SSD, this information was unreasonably hard to come by, hence this list. If you have additions or corrections, please let me know in the comments.

SSDs with USABLE built-in encryption:

Intel 320

This post and this post by an Intel representative confirm that the AES keys on the Intel 320 SSD are encrypted with the user’s ATA password. The second gives more detail on the implementation details, for example that the ATA password itself is also stored in non-reversible hashed form in the drive firmware. The white paper linked to under the Intel 520 heading below confirms the working of the 320 encryption setup.

Intel 520

This is the first Intel SSD making use of the Sandforce SF-2281 controller. Due to a bug in the controller, the drive does AES-128 encryption (instead of the advertised AES-256). AES-128 is still considered to be sufficient for most purposes. After two unsuccessful attempts getting a clear answer on the details of the Intel 520 encryption directly from Intel support, I finally stumbled on this white paper by Intel: Managing Intel Solid-State Drives Using Intel vPro Technology (mirror here). On page 3, in the grey box at the bottom of the page, we see the following text (bold words by me):

How Self-encrypting drives (SEDs) Work: SEDs, such as the Intel® SSD 320 Series and Intel® SSD 520 Series, have a drive controller that automatically encrypts all data to the drive and decrypts all the data from the drive. The disk encryption key is never present in the computer’s processor or memory, where it could be accessed by hackers. The key used to encrypt and decrypt is securely stored only on the drive. Because the disk encryption key is encrypted with the ATA (Advanced Technology Attachment) passwords, the key is made accessible to the drive only after successful user authentication; without the key the data remains encrypted on the media. Authentication of the user is done within the SED by supplying the ATA user password, which is isolated from the OS. Therefore, attacks on OS vulnerabilities cannot affect an SED’s pre-boot process.

That’s a pretty conclusive statement by Intel that both the 320 and the 520 encrypt their AES encryption key with the user-supplied ATA password. After a few weeks and some mails with Intel tech support, I also received the following confirmation concerning the Intel 520 SSD:

Yes, ATA password is used to encrypt the encryption keys stores on the SSD. In other words: The Encryption Keys depends on the ATA password to decrypt them. The ATA password is not used in combination with the Encryption Keys to encrypt the data.

Intel support furthermore confirmed that the Intel 520 is compliant with FIPS-197.

SSDs with PERHAPS USABLE built-in encryption

In these cases there are indications that the mentioned drives are encrypting the encryption keys with the ATA user password, but I have not been able to find more conclusive confirmation. If you find anything, please let me know it the comments, because eventually I’d like to move them out to the list of USABLE or NON-USABLE encryption.

Plextor M5 Pro

On the product page the graphic shows quite clearly that ata passwords are related to encryption keys, but it does not specify in which way these are linked. A reasonable approach would of course be that the key is encrypted with the ATA password, but until that’s confirmed, this drive remains on the “perhaps”-list.

Samsung 840 Pro

Again it’s far too hard to find conclusive information on the encryption implementation. On this product page, we find the following text:

Keep your data safe with Self-Encrypting Drive (SED) Technology Simply enable an HDD password via your computer’s BIOS, and Samsung’s SSD 840 applies data encryption automatically.

This is not as conclusive as I’d like, but there is an implication that there’s a link between the HDD password and the encryption on the Samsung.

Samsung PM830

This drive is not to be confused with the consumer-oriented Samsung 830. The PM830 is a special professional OEM version, found for example in Dell Latitude laptops. There are indications, such as this great 2012 overview paper, titled Hardware-based Full Disk Encryption (In)Security Survey, by Tilo Muller, Tobias Latzo, and Felix C. Freiling (accompanying website with demonstration videos), which mention the PM830 as an example of hardware-based full disk encryption. I’m still searching for the cited spec document that might confirm whether the PM830 encrypts its AES-256 keys with the ATA password, and also the possible password-length limitations.

SSDs with NON-USABLE built-in encryption

OCZ Agility / Vertex 2 / 3 / 4

In this posting on the OCZ Technology Forum, we see that in at least some of the OCZ SSDs, “The encryption key is not directly linked to the ATA Security password (or the BIOS password).” I have not been able to find more specific information about other OCZ offerings. However, my expectations are not very high based on this previous work by OCZ.

Conclusion

  1. Manufacturers of SSDs with built-in encryption are doing an absolutely TERRIBLE job of informing their customers of their specific encryption implementations. For something as critical as full disk encryption, I would expect full disclosure. If the encryption approach is good, disclosing its details won’t affect its security.
  2. The only SSDs that I’d recommend in terms of usable built-in disk encryption are the Intel 320 and 520 drives. It would be great if this list could be expanded. If you have a direct connection to the relevant persons at the various manufacturers, please make use of this and let me know of the results so I can update this blog post.
  3. Your BIOS has to support the full 32 character ATA password specification. The Samsung laptop I’m typing this on only supports 8  character ATA passwords, so I’d think carefully about installing a hardware-based encrypted SSD in here. My desktop with the Intel 520 SSD has the ATASX bios extension and supports up to the full 32 characters. When you buy a new laptop or motherboard, make sure it has a good ATA security extensions implementation, supporting the full 32 characters.
  4. Although ideally the built-in hardware encryption would be usable and secure, the disappointing state of affairs leads me to the conclusion that a good option at this point is still to select an SSD that is impacted as little as possible by the software encryption (avoid the Sandforce controllers, or any other controllers that make use of hardware compression), and then use a solution such as TrueCrypt or luks/dm-crypt (even for a non-Sandforce controller such as on the OCZ Vertex 4, the negative impact is significant, unfortunately). For my next SSD purchase, I will again compare the super-fast hardware encryption of the Intel 520 vs. SSDs that are able to cope to some extent with software encryption, although I am currently leaning towards the Intel 520.

Other resources

  • I’ve written another post documenting my successful experience with r0m30’s open source TCG Opal configuration utility and PBA image.
  • Vincent Tenniglo sent in this article by AnandTech where Anand himself experiments with the TCP Opal 2.0 compliant Crucial M500 and the Windows 8 eDrive support. In theory, with eDrive-compatible drives (meaning Opal 2.0), Windows BitLocker makes use of the drive’s hardware encryption. Ed: Because this is Windows closed-source, we are unfortunately even less sure of what’s happening behind the scenes. It’s an interesting development nonetheless.
  • Great 2012 overview paper, titled Hardware-based Full Disk Encryption (In)Security Survey, by Tilo Muller, Tobias Latzo, and Felix C. Freiling. Also see the accompanying website with demonstration videos.

Updates

  • 2015-02-11: Added link to my msed, PBA and Opal post.
  • 2014-07-02: Updated with AnandTech Opal 2.0 Windows eDrive Crucial M500 article submitted by Vincent Tenniglo.
  • 2013-02-08: Updated with confirmation by Intel tech support concerning the Intel 520.
  • 2013-01-15: Updated link to Muller et al. overview paper.
  • 2012-12-23: Added the Samsung PM830 to the “perhaps” list (thank you Pieter Kitslaar), and linked to great hardware-based full disk encryption overview paper.

Adding the ATA Security eXtension BIOS to AMIBIOS (Asus P5KC)

I’ve just purchased an Intel 520 SSD drive, which does hardware-based AES encryption of the whole disk, and is clever enough to encrypt the AES passphrase with the ATA / HDD password. This encryption implementation was my primary reason for getting this specific SSD. Many modern SSDs also employ hardware-based AES encryption for randomisation and for fast secure erase (they just reset the AES key!), but do NOT use the ATA password to encrypt the keys, so the encryption is far less effective at protecting your precious data. As far as my current information goes, the Intel 320, 520 and 710 drives do it correctly, as does the Samsung SSD 840 Pro and the Kingston SSDNow 200V+.

However, the AMI-BIOS in the Asus P5KC motherboard in my workstation does not support the ATA Security Mode Feature Set, and hence does not allow me to set the ATA password, or to enter the set ATA password at bootup so that the SSD can be unlocked. Enter the ATA Security eXtension BIOS, or ATASX, a piece of ROM BIOS code that you can add to your system or network ROM in various ways, that then gives you the required ATA Security Mode Feature Set components.

This post documents the exact steps I took to patch the AMI-BIOS of my Asus P5KC motherboard. If you follow these instructions, you do so entirely at your own risk. 

I made use of method 2 for the AMI-BIOS, that is to integrate the ATASX as a PCI extension ROM, targeted at the boot room on the built-in network card, into a BIOS ROM image, which I could then flash on the motherboard using the built-in EZ-Flash tool.

  1. The ATASX.ROM needs to be configured with the network and vendor id of your network card. Under Linux, I used “lspci -nn”, which returned “02:00.0 Ethernet controller [0200]: Atheros Communications Inc. Attansic L1 Gigabit Ethernet [1969:1048] (rev b0)” for the ethernet card. At the very end, you can see that the vendor id is 1969 and the device id is 1048.
  2. Using bromcfg.exe (part of the ATASX download) in a dosbox (it’s a dos utility, and I only have Windows 7 64bit on my laptop, which can’t run dos EXEs) I loaded ATASX.ROM and entered the correct vendor and device IDs. I left the default passwords blank, and the default Ctrl-S delay at 1 second.
  3. Downloaded the latest Asus P5KC .ROM file from the Asus support site.
  4. Downloaded mmtool.exe, loaded the Asus P5KC.ROM file, selected the PCI Option ROM with the vendor and device ID extracted in step 1 in the RunLoc column, and then used the replace tab to replace it with the BROMCFG configured ATASX.ROM, see below for screenshot. Saved the new .ROM file.

    Replacing the network card’s PCI Option ROM with ATASX.
  5. Burn the mmtool-saved ROM with ASUS EZ Flash (Alt-F2 at boot). It should look like this:

    Flashing your new AMI-BIOS.
  6. After rebooting, make sure you have Enabled the “LAN Option ROM” in the BIOS, under Advanced | Onboard Devices Configuration, else ATASX.ROM will never get a chance to start!

At your next boot, you should see the ATASX CTRL+S message:

Press CTRL+S to enter the ATASX setup!

If you press Control-S on time, you should be greeted with the ATASX drive selection screen (the Intel 520 SSD is not installed yet, you’re seeing my Barracuda only):

Press CTRL+S to enter the ATASX setup!

From which you can select a drive and then configure various ATA Security related variables, such as the master and user HDD passwords, which is exactly what we were after:

ATASX drive detail screen, on which the HDD passwords can be set.

Update on 2012-12-23

I’ve discovered one more caveat: ATASX unfortunately does not support drives in AHCI mode. AHCI mode can be faster than IDE mode, especially for multi-threaded disk access.

Update on 2012-12-01

I now have this working with an Intel 520 SSD. There is one caveat though: If your machine suspends to RAM (S3), the drive goes into its locked state. At resume, there is no secure way to supply the drive password, and so it remains locked. In many cases this means that S3 suspend-to-ram is not usable for password protected drives. This seems to be a common problem with desktops and also some laptops, as can be seen here on askubuntu, here on the intel communities, here on the ATASX forums, and here in the German C’T magazine.