Hardware-based full disk encryption: Difference between revisions

Revision as of 20:53, 19 May 2020

Revision as of 18:18, 22 May 2020

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#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 initializedinitialised, 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.

==Hard Hardware-based full disk driveencryption Types FDE==

=== 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://www.webcitation.org/65fUDqdql?url=http://www.trustedcomputinggroup.org/solutions/data_protection |archive-date=2012-02-23 |df= }}</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.

[[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. HDD drives have become a comodity 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}}</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 retrieved 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}}.

For example,: [[ViaSat|Viasat UK (formerly Stonewood Electronics)]] with their FlagStone and 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> 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}}</ref> with an [[Radio-frequency identification|RFID]] token.

=== Removable Hard Drive FDE ===

The Inserted [[hard disk drive|Hard Drive]] 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.

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*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}}</ref> so the drive's interface is open to attack.

=== Chipset FDE ===

The encryptor bridge and chipset (BC) is placed between the computer and the standard hard disk drive, encrypting every sector written to it.

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

InFor Data at Rest 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 bytes (2^256) to unlock.

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

[[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 sanitizationsanitisation]] which can be a lengthy (and costly) process. For example, an unencrypted and unclassified computer hard drive that requires sanitizingsanitising to conform with [[United States Department of Defense|Department of Defense]] Standards must be overwritten 3+ times;<ref>http://www-03.ibm.com/systems/resources/IBM_Certified_Secure_Data_Overwrite_Service_SB.pdf</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://www.researchandmarkets.com/reports/683004/ssd_story_slow_on_the_uptake.pdf</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 sanitizationsanitisation 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. There is no way to retrieve data once erased in this way {{Citation needed|reason=see Talk page, data remanence exists in memory chips used in SED, so the original decryption key can technically be recovered in several cases|date=July 2016}} - the keys are self generated randomly so there is no record of them anywhere. Protecting this data from accidental loss or theft is achieved through a consistent and comprehensive data backup policy.

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/encryption-eclypt-core |website=Viasat.com |publisher=Viasat |accessdate=2020-05-22 |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]]. AllIn SEDs, all data requests are intercepted inby the SEDtheir [[firmware]], andthat willdoes not allow decryption to take place unless the system has been [[Booting|booted]] from the special SED [[operating system]] which will then loadloads 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.

=== Vulnerabilities ===

TypicalTypically self-encrypting drivesFDE, once unlocked, will remain unlocked as long as power is provided.<ref name="sed-attacks" /> Researchers at [[University of Erlangen-Nuremberg|Universität Erlangen-Nürnberg]] have demonstrated a number of attacks based on moving the drive to another computer without cutting power.<ref name="sed-attacks">{{cite web|url=https://www1.cs.fau.de/sed |title=Hardware-based Full Disk Encryption (In)Security &#124; IT-Sicherheitsinfrastrukturen (Informatik 1) |publisher=.cs.fau.de |date= |accessdate=2013-08-06}}</ref> Additionally, it may be possible to reboot the computer into an attacker-controlled operating system without cutting power to the drive.

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" />

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The firmware of the drive may be compromised<ref>{{cite web | url = https://www.wired.com/2015/02/nsa-firmware-hacking/ | title = How the NSA’s Firmware Hacking Works and Why It’s So Unsettling | first = Kim | last = Zetter | date = 2015-02-22 | work = Wired }}</ref><ref>{{cite web | url = https://www.theregister.co.uk/2015/02/17/kaspersky_labs_equation_group/ | title = Your hard drives were RIDDLED with NSA SPYWARE for YEARS | 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 also been criticised 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 document|url=http://www.secude.com/html/?id=1375|title=Closing the Legacy Gap|publisher=Secude|date=February 21, 2008|accessdate=2008-02-22}}{{dead link|date=September 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> however Enclosed hard disk drive FDE and Removable Hard Drive FDE are often installed on a single drive basis.

==See also==