Hardware-based full disk encryption

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

Contents

Hardware-FDE has two major components: the hardware encryptor and the data store. There are currently four varieties of hardware-FDE in common use:

  1. Hard disk drive (HDD) FDE (self-encrypting drive)
  2. Enclosed hard disk drive FDE
  3. Removable hard disk drive FDE
  4. 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 types

Hard disk drive FDE

Usually referred to as self-encrypting drive (SED). HDD FDE is made by HDD vendors using the OPAL and Enterprise standards developed by the Trusted Computing Group. [1] 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 CPU via either a software pre-boot authentication environment (i.e., with a software-based full disk encryption component - hybrid full disk encryption) or with a BIOS password.

Hitachi, Micron, Seagate, Samsung, and Toshiba are the disk drive manufacturers offering Trusted Computing Group Opal Storage Specification Serial ATA drives. HDDs have become a commodity so SED allow drive manufacturers to maintain revenue. [2] Older technologies include the proprietary Seagate DriveTrust, and the older, and less secure, 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 hard drive form factor case the encryptor (BC), key store and a smaller form factor, commercially available, hard disk drive is enclosed.

For example: Viasat UK (formerly Stonewood Electronics) with their FlagStone, Eclypt [3] and DARC-ssd [4] drives or GuardDisk [5] with an RFID token.

Removable hard drive FDE

The inserted hard drive FDE allows a standard form factor hard disk drive to be inserted into it. The concept can be seen on [6]

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.

Intel announced the release of the Danbury chipset [8] but has since abandoned this approach.[ citation needed ]

Characteristics

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 computer's processor.

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

For 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 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.

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. [9] Without the old key, the old data becomes irretrievable and therefore an efficient means of providing 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 Department of Defense Standards must be overwritten 3+ times; [10] a one Terabyte Enterprise SATA3 disk would take many hours to complete this process. Although the use of faster solid-state drives (SSD) technologies improves this situation, the take up by enterprise has so far been slow. [11] 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 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, [12] 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 booted from the special SED operating system which then loads the MBR of the encrypted part of the drive. This works by having a separate 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

Typically FDE, once unlocked, will remain unlocked as long as power is provided. [13] Researchers at Universität Erlangen-Nürnberg have demonstrated a number of attacks based on moving the drive to another computer without cutting power. [13] 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. [13]

The firmware of the drive may be compromised [14] [15] 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[ by whom? ]. 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 full disk encryption solutions. [16] however Enclosed hard disk drive FDE and Removable Hard Drive FDE are often installed on a single drive basis.

See also

Related Research Articles

The Encrypting File System (EFS) on Microsoft Windows is a feature introduced in version 3.0 of NTFS that provides filesystem-level encryption. The technology enables files to be transparently encrypted to protect confidential data from attackers with physical access to the computer.

<span class="mw-page-title-main">TrueCrypt</span> Discontinued source-available disk encryption utility

TrueCrypt is a discontinued source-available freeware utility used for on-the-fly encryption (OTFE). It can create a virtual encrypted disk within a file, or encrypt a partition or the whole storage device.

Data security means protecting digital data, such as those in a database, from destructive forces and from the unwanted actions of unauthorized users, such as a cyberattack or a data breach.

Disk encryption software is a computer security software that protects the confidentiality of data stored on computer media by using disk encryption.

In computing, data recovery is a process of retrieving deleted, inaccessible, lost, corrupted, damaged, or formatted data from secondary storage, removable media or files, when the data stored in them cannot be accessed in a usual way. The data is most often salvaged from storage media such as internal or external hard disk drives (HDDs), solid-state drives (SSDs), USB flash drives, magnetic tapes, CDs, DVDs, RAID subsystems, and other electronic devices. Recovery may be required due to physical damage to the storage devices or logical damage to the file system that prevents it from being mounted by the host operating system (OS).

Encryption software is software that uses cryptography to prevent unauthorized access to digital information. Cryptography is used to protect digital information on computers as well as the digital information that is sent to other computers over the Internet.

<span class="mw-page-title-main">BitLocker</span> Disk encryption software for Microsoft Windows

BitLocker is a full volume encryption feature included with Microsoft Windows versions starting with Windows Vista. It is designed to protect data by providing encryption for entire volumes. By default, it uses the Advanced Encryption Standard (AES) algorithm in cipher block chaining (CBC) or "xor–encrypt–xor (XEX)-based Tweaked codebook mode with ciphertext Stealing" (XTS) mode with a 128-bit or 256-bit key. CBC is not used over the whole disk; it is applied to each individual sector.

The Linux Unified Key Setup (LUKS) is a disk encryption specification created by Clemens Fruhwirth in 2004 and originally intended for Linux.

Disk encryption is a technology which protects information by converting it into code that cannot be deciphered easily by unauthorized people or processes. Disk encryption uses disk encryption software or hardware to encrypt every bit of data that goes on a disk or disk volume. It is used to prevent unauthorized access to data storage.

<span class="mw-page-title-main">BestCrypt</span> Commercial disk encryption app available for Windows, Linux, macOS and Android

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This is a technical feature comparison of different disk encryption software.

<span class="mw-page-title-main">Private Disk</span>

Private Disk is a disk encryption application for the Microsoft Windows operating system, developed by Dekart SRL. It works by creating a virtual drive, the contents of which is encrypted on-the-fly; other software can use the drive as if it were a usual one.

In computer security, a cold boot attack is a type of side channel attack in which an attacker with physical access to a computer performs a memory dump of a computer's random-access memory (RAM) by performing a hard reset of the target machine. Typically, cold boot attacks are used for retrieving encryption keys from a running operating system for malicious or criminal investigative reasons. The attack relies on the data remanence property of DRAM and SRAM to retrieve memory contents that remain readable in the seconds to minutes following a power switch-off.

Pre-boot authentication (PBA) or power-on authentication (POA) serves as an extension of the BIOS, UEFI or boot firmware and guarantees a secure, tamper-proof environment external to the operating system as a trusted authentication layer. The PBA prevents anything being read from the hard disk such as the operating system until the user has confirmed they have the correct password or other credentials including multi-factor authentication.

Data erasure is a software-based method of data sanitization that aims to completely destroy all electronic data residing on a hard disk drive or other digital media by overwriting data onto all sectors of the device in an irreversible process. By overwriting the data on the storage device, the data is rendered irrecoverable.

The Opal Storage Specification is a set of specifications for features of data storage devices that enhance their security. For example, it defines a way of encrypting the stored data so that an unauthorized person who gains possession of the device cannot see the data. That is, it is a specification for self-encrypting drives (SED).

<span class="mw-page-title-main">VeraCrypt</span> Free and open-source disk encryption utility

VeraCrypt is a free and open-source utility for on-the-fly encryption (OTFE). The software can create a virtual encrypted disk that works just like a regular disk but within a file. It can also encrypt a partition or the entire storage device with pre-boot authentication.

Rombertik is spyware designed to steal confidential information from targets using Internet Explorer, Firefox, or Chrome running on Windows computers. It was first publicized by researchers at Cisco Talos Security and Intelligence Group.

Crypto-shredding is the practice of 'deleting' data by deliberately deleting or overwriting the encryption keys. This requires that the data have been encrypted. Data may be considered to exist in three states: data at rest, data in transit and data in use. General data security principles, such as in the CIA triad of confidentiality, integrity, and availability, require that all three states must be adequately protected.

<span class="mw-page-title-main">Evil maid attack</span> Type of computer security breach

An evil maid attack is an attack on an unattended device, in which an attacker with physical access alters it in some undetectable way so that they can later access the device, or the data on it.

References

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