Hardware-based full disk encryption: Difference between revisions

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{{short description|Cryptographic hardware}}

{{NPOV language|date=April 2013}}

'''Hardware-based full disk encryption''' ('''FDE''') is available from many [[hard disk drive]] (HDD/[[Solid-state drive|SSD]]) vendors, including: [[Hitachi]], Integral Memory, iStorage Limited, [[Micron Technology|Micron]], [[Seagate Technology]], [[Samsung]], [[Toshiba]], [[ViaSat|Viasat UK]], and [[Western Digital]]. The [[symmetric-key algorithm|symmetric encryption key]] is maintained independently from the computer's [[Central processing unit|CPU]], thus allowing the complete data store to be encrypted and removing computer memory as a potential attack vector.

'''Hardware-based full disk encryption''' ('''FDE''') is available from many [[hard disk drive]] (HDD/[[Solid-state drive|SSD]]) vendors, including: [[Hitachi]], Integral Memory, iStorage Limited, [[Micron Technology|Micron]], [[Seagate Technology]], [[Samsung]], [[Toshiba]], [[ViaSat|Viasat UK]], [[Western Digital]]. The [[symmetric-key algorithm|symmetric encryption key]] is maintained independently from the computer's [[Central processing unit|CPU]], thus allowing the complete data store to be encrypted and removing computer memory as a potential attack vector.

Hardware-FDE has two major components: the hardware encryptor and the data store.

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#Hard disk drive (HDD) FDE (self-encrypting drive)

#Enclosed hard disk drive FDE

#Removable Hardhard Drivedisk drive FDE

#Bridge and [[Chipset]] (BC) FDE

Hardware designed for a particular purpose can often achieve better performance than [[disk encryption software]], and disk encryption hardware can be made more transparent to software than encryption done in software. As soon as the key has been initialised, the hardware should in principle be completely transparent to the OS and thus work with any OS. If the disk encryption hardware is integrated with the media itself the media may be designed for better integration. One example of such design would be through the use of physical sectors slightly larger than the logical sectors.

== Hardware-based full disk encryption Typestypes ==

=== Hard disk drive FDE ===

Usually referred to as '''self-encrypting drive''' ('''SED''').

HDD FDE is made by HDD vendors using the [[Opal Storage Specification|OPAL]] and Enterprise standards developed by the [[Trusted Computing Group]].<ref>{{cite web |url=http://www.trustedcomputinggroup.org/solutions/data_protection |title=Trusted Computing Group Data Protection page |publisher=Trustedcomputinggroup.org |date= |access-date=2013-08-06 |url-status=dead |archive-url=https://wwwarchive.webcitation.orgtoday/20120915073808/65fUDqdql?url=http://www.trustedcomputinggroup.org/solutions/data_protection |archive-date=2012-0209-23 |df=15 }}</ref> [[Key management]] takes place within the hard disk controller and encryption keys are 128 or 256 [[bit]] [[Advanced Encryption Standard]] (AES) keys. [[Authentication]] on power up of the drive must still take place within the [[Central processing unit|CPU]] via either a [[software]] [[pre-boot authentication]] environment (i.e., with a [[Disk encryption software|software-based full disk encryption]] component - hybrid full disk encryption) or with a [[BIOS]] password. In additions, some SEDs support [[IEEE 1667]] standard.<ref>{{Cite web |title=The Value of Crucial Hardware Encryption |url=https://eu.crucial.com/support/hardware-encryption |access-date=2024-11-16 |website=Crucial |language=en}}</ref>

[[Hitachi]], [[Micron Technology|Micron]], [[Seagate Technology|Seagate]], [[Samsung]], and [[Toshiba]] are the disk drive manufacturers offering [[Trusted Computing Group|TCG]] [[Opal Storage Specification|OPAL]] [[Serial ATA|SATA]] drives. HDDs have become a commodity so SED allow drive manufacturers to maintain revenue.<ref>{{cite web |last1=Skamarock |first1=Anne |title=Is Storage a commodity |url=https://www.itworld.com/article/2799690/is-storage-a-commodity-.html |website=ITWorld.com |publisher=Network World |accessdate=2020-05-22 |date=2020-02-21 }}{{Dead link|date=August 2025 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> Older technologies include the proprietary Seagate DriveTrust, and the older, and less secure, [[Parallel ATA|PATA]] Security command standard shipped by all drive makers including [[Western Digital]]. Enterprise SAS versions of the TCG standard are called "TCG Enterprise" drives.

=== Enclosed hard disk drive FDE ===

Within a standard [[Harddrive#Form factors|hard drive form factor]] case the encryptor (BC), [[Cryptographic key|key]] store and a smaller form factor, commercially available, hard disk drive is enclosed.

*The enclosed hard disk drive's case can be [[tamper-evident]], so when retrievedinspected the user can be assured that the [[Data breach|data has not been compromised]].

*The encryptors electronics including the [[Cryptographic key|key]] store and integral hard drive (if it is [[Solid-state drive|solid-state]]) can be protected by other [[Tamper resistance|tamper respondent]] measures.

*The key can be [[Crypto-shredding|purged]], allowing a user to prevent his [[Authentication factors#Authentication factors|authentication parameters]] being used without destroying the encrypted data. Later the same [[Cryptographic key|key]] can be re-loaded into the Enclosed hard disk drive FDE, to retrieve this data.

*Tampering is not an issue for SEDs as they cannot be read without the decryption key, regardless of access to the internal electronics {{Clarify|reason=see Talk page, decryption keys can be recovered from the internal electornics in several cases|date=July 2016}}.

Examples include [[ViaSat|Viasat UK (formerly Stonewood Electronics)]] with their FlagStone, Eclypt<ref name="softpedia">{{cite web|url=http://news.softpedia.com/news/Stonewood-039-s-Eclypt-Drive-the-AES-256-Data-Fortress-84632.shtml |title=Softpedia on Eclypt Drive AES-256 |publisher=News.softpedia.com |date=2008-04-30 |accessdate=2013-08-06}}</ref> and DARC-ssd<ref>{{cite web |title=Data At Rest (DAR) encryption solutions |url=https://www.viasat.com/products/cybersecurity/data-at-rest-encryption/ |website=www.Viasat.com |publisher=Viasat, Inc. ©2023 |access-date=2 February 2023}}</ref> drives or GuardDisk <ref>{{cite web |title=Hardware Disk Encryption for the Masses, Finally! |url=https://www.turbotas.co.uk/2003/07/30/hardware-disk-encryption-for-the-masses-finally/ |website=turbotas.co.uk |publisher=Turbotas |accessdate=2020-05-22 |date=2003-05-30 |archive-date=2020-09-25 |archive-url=https://web.archive.org/web/20200925191820/https://www.turbotas.co.uk/2003/07/30/hardware-disk-encryption-for-the-masses-finally/ |url-status=dead }}</ref> with an [[Radio-frequency identification|RFID]] token.

For example: Viasat UK (formerly Stonewood Electronics) with their FlagStone and Eclypt drives or GuardDisk with an RFID token.

=== Removable Hardhard Drivedrive FDE ===

The Insertedinserted [[hard disk drive|Hardhard Drivedrive]] FDE allows a standard [[List of disk drive form factors|form factor]] [[hard disk drive]] to be inserted into it. The concept can be seen on <ref>{{cite web |title=Removable Drives |url=https://www.cru-inc.com/industries/removables/ |website=www.Cru-inc.com |publisher=CRU |accessdate=2020-05-15}}</ref>

*This is an improvement on removing [unencrypted] [[hard disk drive|hard drives]] from a [[computer]] and storing them in a [[safe]] when not in use.

*This design can be used to encrypt multiple [[hard disk drive|drives]] using the same [[Cryptographic key|key]].

*Generally they are not securely locked<ref>{{cite web |title=Sapphire Cipher Snap-In |url=https://www.addonics.com/products/ssna256eu.php |website=Addonics.com |publisher=Addonics |accessdate=2020-05-15 |archive-date=2020-12-01 |archive-url=https://web.archive.org/web/20201201214820/https://www.addonics.com/products/ssna256eu.php |url-status=dead }}</ref> so the drive's interface is open to attack.

=== Chipset FDE ===

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Hardware-based encryption when built into the drive or within the drive enclosure is notably transparent to the user. The drive, except for bootup authentication, operates just like any drive, with no degradation in performance. There is no complication or performance overhead, unlike [[disk encryption software]], since all the encryption is invisible to the [[operating system]] and the host [[Central processing unit|computer's processor]].

The two main use cases are [[Data at Restrest]] protection, and Cryptographic Disk Erasure.

For Data at Restrest protection a computer or laptop is simply powered off. The disk now self-protects all the data on it. The data is safe because all of it, even the OS, is now encrypted, with a secure mode of [[Advanced Encryption Standard|AES]], and locked from reading and writing. The drive requires an authentication code which can be as strong as 32 {{nbs}}bytes (2^256{{nbs}}bits) to unlock.

==={{anchor|Crypto erase}}Disk sanitisation===

[[Crypto-shredding]] is the practice of 'deleting' data by (only) deleting or overwriting the encryption keys.

When a cryptographic disk erasure (or crypto erase) command is given (with proper authentication credentials), the drive self-generates a new media encryption key and goes into a 'new drive' state.<ref>{{cite web |title=10 Reasons to Buy Self-Encrypting Drives |author=Trusted Computing Group |url=https://www.trustedcomputinggroup.org/wp-content/uploads/10-Reasons-to-Buy-SEDs_Sept.2010.pdf |year=2010 |publisher=Trusted Computing Group |accessdate=2018-06-06}}</ref> Without the old key, the old data becomes irretrievable and therefore an efficient means of providing [[Data erasure|disk sanitisation]] which can be a lengthy (and costly) process. For example, an unencrypted and unclassified computer hard drive that requires sanitising to conform with [[United States Department of Defense|Department of Defense]] Standards must be overwritten 3+ times;<ref>[https://web.archive.org/web/20130723215341/http://www-03.ibm.com/systems/resources/IBM_Certified_Secure_Data_Overwrite_Service_SB.pdf www-03.ibm.com] {{Bare URL PDF|date=March 2022}}</ref> a one Terabyte Enterprise SATA3 disk would take many hours to complete this process. Although the use of faster [[solid-state drive]]s (SSD) technologies improves this situation, the take up by enterprise has so far been slow.<ref>http{{cite web |title=Slow on the Uptake |url=https://wwwdocplayer.researchandmarkets.comnet/reports/683004/ssd_story_slow_on_the_uptake30164112-Ssd-story-slow-on-the-uptake.pdfhtml |access-date=18 February 2021}}</ref> The problem will worsen as disk sizes increase every year. With encrypted drives a complete and secure data erasure action takes just a few milliseconds with a simple key change, so a drive can be safely repurposed very quickly. This sanitisation activity is protected in SEDs by the drive's own key management system built into the firmware in order to prevent accidental data erasure with confirmation passwords and secure authentications related to the original key required.

When [[Cryptographic key|keys]] are self -generated randomly, generally there is no method to store a copy to allow [[data recovery]]. In this case protecting this data from accidental loss or theft is achieved through a consistent and comprehensive data backup policy. The other method is for user-defined keys, for some Enclosed hard disk drive FDE ,<ref>{{cite web |title=Eclypt Core Encrypted Internal Hard Drive |url=https://www.viasat.com/products/encryptioncybersecurity/data-eclyptat-corerest-encryption/ |website=Viasat.com |publisher=Viasat |accessdate=20202021-0502-2217 |date=2020}}</ref>, to be generated externally and then loaded into the FDE.

===Protection from alternative boot methods===

Recent hardware models circumvents [[booting]] from other devices and allowing access by using a dual [[Master Boot Record]] (MBR) system whereby the MBR for the operating system and data files is all encrypted along with a special MBR which is required to boot the [[operating system]]. In SEDs, all data requests are intercepted by their [[firmware]], that does not allow decryption to take place unless the system has been [[Booting|booted]] from the special SED [[operating system]] which then loads the [[Master boot record|MBR]] of the encrypted part of the drive. This works by having a separate [[Disk partitioning|partition]], hidden from view, which contains the proprietary [[operating system]] for the encryption management system. This means no other boot methods will allow access to the drive.{{citation needed|date=December 2024}}

=== Vulnerabilities ===

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When a computer with a self-encrypting drive is put into [[sleep mode]], the drive is powered down, but the encryption password is retained in memory so that the drive can be quickly resumed without requesting the password. An attacker can take advantage of this to gain easier physical access to the drive, for instance, by inserting extension cables.<ref name="sed-attacks" />

The firmware of the drive may be compromised<ref>{{cite webmagazine | url = https://www.wired.com/2015/02/nsa-firmware-hacking/ | title = How the NSA’sNSA's Firmware Hacking Works and Why It’sIt's So Unsettling | first = Kim | last = Zetter | date = 2015-02-22 | workmagazine = Wired }}</ref><ref>{{cite web | url = https://www.theregister.co.uk/2015/02/17/kaspersky_labs_equation_group/ | title = Your hard drives were RIDDLEDriddled with NSA SPYWAREspyware for YEARSyears | first = Darren | last = Pauli | date = 2015-02-17 | work = The Register }}</ref> and so any data that is sent to it may be at risk. Even if the data is encrypted on the physical medium of the drive, the fact that the firmware is controlled by a malicious third-party means that it can be decrypted by that third-party. If data is encrypted by the operating system, and it is sent in a scrambled form to the drive, then it would not matter if the firmware is malicious or not.

=== Criticism ===

Hardware solutions have alsogained been criticisedcriticism for being poorly documented{{fact|date=April 2014}}. Many aspects of how the encryption is done are not published by the vendor. This leaves the user with little possibility to judge the security of the product and potential attack methods. It also increases the risk of a [[vendor lock-in]].

In addition, implementing system wide hardware-based full disk encryption is prohibitive for many companies due to the high cost of replacing existing hardware. This makes migrating to hardware encryption technologies more difficult and would generally require a clear migration and central management solution for both hardware- and software-based [[Disk encryption#Full disk encryption|full disk encryption]] solutions.<ref>{{cite documentweb|url=http://www.secude.com/html/?id=1375|archive-url=https://archive.today/20120909075410/http://www.secude.com/html/?id=1375|url-status=dead|archive-date=September 9, 2012|title=Closing the Legacy Gap|publisher=Secude|date=February 21, 2008|accessdate=2008-02-22}}</ref> however Enclosed hard disk drive FDE and Removable Hard Drive FDE are often installed on a single drive basis.

==See also==

* [[Disk encryption hardware]] <!-- The page linked contains unbalanced criticism should to be merged into this page -->

* [[Disk encryption software]]

* [[Crypto-shredding]]

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==References==

{{Reflist}}

[[Category:Disk encryption]]