Evaluation Of Open Source Cryptographic Systems Computer Science Essay

The intent of this undertaking is to measure and measure four open-source cryptographic package, DM-Crypt/CryptSetup, DiskCryptor, TrueCrypt and eCryptfs, for usage by the Defence Science and Technology Agency ( DSTA ) . We hope that through this undertaking we would be able to assist DSTA in choosing the best disc encoding package that would outdo suit their demands.

Introduction

Cryptanalysis, in simple footings is the procedure that consists of Encryption and Decryption. In Encryption, it is defined as the procedure of changing legible clear informations into indecipherable informations for the intent of protecting the information from unwanted exposure or alteration during storage or transmittal. Decryption therefore is the procedure of returning indecipherable informations into clear informations, which is the antonym of Encryption.

Cryptanalysis relies upon two basic constituents: an algorithm and a key. The algorithm is a mathematical map which is normally pre-defined and approved by assorted standard organic structures, such as NIST ( National Institutes of Standards and Technology ) , and besides the key which is a parametric quantity used in the transmutation either manually supplied or automatically generated.

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There are three basic types of sanctioned cryptanalytic algorithms as defined by NIST: Symmetric Key Algorithms, Asymmetric Key Algorithms and Cryptographic Hash Functions.

Symmetric key algorithms are the most basic and widely used algorithm to protect informations in twenty-four hours to twenty-four hours activities. The basic parametric quantities needed in the encoding procedure are the informations and the secret key. An illustration would be in a state of affairs in which a user wants to direct a plaintext ( clear informations ) in secret, to another user. The user would merely code the plaintext utilizing a secret key that he would provide to the encoding algorithm and the consequence would be a ciphertext ( indecipherable informations ) , which is an encrypted plaintext.

Asymmetric key algorithms are more advanced and unafraid and normally used in endeavor systems, concern minutess or in state of affairss that require higher degrees of informations security. Asymmetric cardinal algorithms rely on a cardinal brace construct which requires a public key, which is normally known and can be distributed to everyone, and a private key, which merely the proprietor of the cardinal knows and is ne’er distributed. Both the keys are mathematically related to each other, and encoding with one key can merely be decrypted with the other key. Asymmetric cardinal algorithms are normally slower than symmetric algorithms. Use of these keys allows protection of the genuineness of a message by making a digital signature of a message utilizing the private key which can be verified utilizing the public key.

Cryptanalytic hash maps are particular one manner keyless algorithms ( although they can be used in a manner in which keys are used ) . They are sometimes used in concurrence with private key or public cardinal cryptanalysis. It is a type of one-way encoding, which when applied to a message, it can non be recovered. Unlike key-based cryptanalysis, the chief end of hash maps is non to code informations for later decoding, but to make a kind of a alone digital fingerprint of a message. The value derived from using the hash map can be re-calculated at the having terminal, to guarantee that the message has non been tampered with during theodolite.

However asymmetric cardinal algorithms and cryptanalytic hash maps are out of the range of this rating. More information about the three approved cryptanalytic algorithms can be found at NIST Special Publication 800-21 [[ 1 ]] .

This rating deals chiefly with Disk Encryption ( includes external devices such as CD/DVDs, USB Drives and etc. ) and normally uses symmetric cardinal algorithms.

Normally in Disk Encryption, the symmetric key that the disc is encrypted to is placed in the RAM, so any file accessed by the system is transparently decrypted for usage. Any file saved to the disc is besides transparently encrypted before being saved to the disc. In theory all files in the drives/disk is really ever encrypted. However, anyone that has entree to the running computing machine will besides hold entree to the files. Therefore Disk Encryption protections normally apply to discs that are non in usage, such as when the computing machine is shutdown.

Premise

Our premise is that DSTA approximately knows the procedures of encoding and decoding and have done some basic research sing the 4 Crypto-Systems that were chosen for this rating.

Caution

Backup all informations prior to encoding. Failure to make so might do possible loss of of import informations, as it can ne’er be recovered. Although a possible manner to retrieve the information is to seek and check the key that was used during the encoding procedure, nevertheless an effort would take 1000000s of old ages to finish depending on the size of the key. It is hence wise to both back up the informations, and if possible back up the key that was used. Of class the backed up key will necessitate to be protected from unauthorised entree, but that is out the range of this rating.

Evaluation at a glimpse

DM-Crypt

DiskCryptor

TrueCrypt

eCryptfs

Version Used for Evaluation

V1.1.3

V 0.9.593.106

V 7.0a

V 83

Operating Mode ( Encryption Layer )

Whole Disk, Partition, File, Hibernation File

Whole Disk, Partition,

Hibernation File

Whole Disk, Partition, File, Hibernation File ( Windows Merely )

File and Folder Merely

Operating System Support

Linux

Windows Merely

Windows, Linux, Macintosh

Linux Merely

Licensing / Copyrights

GPL v2

GPL v3

TrueCrypt Collective License

GPL v2

User Friendliness

Console Based Merely

GUI Based,

Console Mode Available

GUI Based,

Console Mode Available ( Linux Merely )

Console Based Merely

Encoding Algorithms Available

AES

Snake

Twofish

Blowfish

AES

Snake

Twofish

AES

Snake

Twofish

AES

Blowfish

DES3 EDE

Cast5

Cast6

Twofish

Encoding and Decryption Modes

Complete blood count

LRW

Crosstalk

Crosstalk Merely

Crosstalk Merely

CBC with Secret IVs Merely

Encoding of Swap Space ( Virtual Memory )

Yes

Yes

Yes

No

Key manageableness

LUKS divider shops all the keys

Heading may be backup and restored

Heading can be backup and restored, rescue disc option is besides available

N/A

Crypto-Systems Overview

DM-Crypt/CryptSetup

DM-Crypt, besides known as Device Mapper Crypt, is merely designed to work on Linux based distributions. DM-Crypt is based on the Device-Mapper Infrastructure and hence is a native faculty of the Linux 2.6+ Kernel. Thus the user is able to lade the faculties to be used when needed. The Device-Mapper Infrastructure serves as a generic model to map one block device to another. It works as an intermediary by treating informations passed in from a practical block device, and go throughing the end point informations on to another block device ( difficult discs, CD/DVDs, etc ) , kind of supplying a common interface for different block devices with different filesystems to pass on with other block devices. DM-Crypt utilizations Linux Crypto-APIs to ease its encoding and decoding procedures.

In add-on to that, DM-Crypt besides addresses some dependability jobs of CryptoLoop, which was its predecessor. DM-Crypt presently relies on either one of the two available frontends to create/delete and activate/deactivate encrypted volumes, and manage hallmark. The two presently available frontends are CryptSetup and CryptMount. Our rating will be based on CryptSetup frontend. CryptSetup [[ 2 ]] is used to handily setup DM-Crypt volumes and encoding and decoding processs.

More information can be found at DM-Crypt Homepage. [[ 3 ]]

DiskCryptor

DiskCryptor was developed by Ntldr, a forum name. When it was foremost released, it was the first unfastened beginning ( GPL Licensed [[ 4 ]] ) full disc encoding system for MS Windows that offers encoding of all disc dividers, including the system divider. One of the few jobs we experienced with DiskCryptor is that its chief home page is Russian ; nevertheless they do hold an English version of the home page. In add-on their official forum is manned by chiefly Russians, and it ‘s uncommon to happen English stations, but aid can still be found if you ‘re patient plenty to wait for a answer.

DiskCryptor is simple to utilize, nevertheless there are non much characteristics in comparing to other Crypto-Systems but it still provides a good solution for difficult disc encoding.

More information can be found at DiskCryptor English Homepage. [[ 5 ]]

TrueCrypt

TrueCrypt is presently by far the most celebrated difficult disc encoding package in comparing to the popularity of other solutions. There is an extended certification about all the maps and characteristics of the merchandise at their home page. In add-on they have a broad user voluntary base to assist out with development and designation of bugs. It has a batch of alone characteristics that is non present in other Crypto-Systems such as the construct of plausible deniability [[ 6 ]] , in which a secret volume can be created inside a false outer volume to conceal sensitive informations in a state of affairs where the proprietor needs to uncover the volume watchword in the instance of a existent life physical onslaught.

Other than that TrueCrypt provides a nice and elaborate User Interface to enable any user to easy and safely utilize the application. TrueCrypt besides provides an extended PDF Manual included in the installing file if the user of all time needs any aid offline.

More information can be found at TrueCrypt Homepage. [[ 7 ]]

eCryptfs

eCryptfs ( the Enterprise Cryptographic Filesystem ) is a POSIX-compliant encrypted filesystem ( PortableA OperatingA SystemA Interface [ for UNIX ] A is the name of a household of relatedA criterions specified by theA IEEEA to specify theA application programming interface ) that has been included in Ubuntu since version 9.04. It is a signifier of disc encoding package similar to Microsoft ‘s BitLocker Drive Encryption and Apple ‘s FileVault ; nevertheless eCryptfs is merely intended for usage in Linux.

Unlike other Linux encoding solutions such as DM-Crypt, eCryptfs is a kernel-native stacked cryptanalytic filesystem alternatively of full disc encoding. Filesystem encoding has certain advantages and disadvantages over block-level encoding. Stacked filesystems bed on top of bing mounted filesystems that are referred to as lower filesystems. eCryptfs is a stacked filesystem that encrypts and decrypts the files as they are written to or read from the lower filesystem.

eCryptfs purposes to supply the flexibleness of a Pretty Good Privacy ( PGP ) application as a crystalline meat service. For that ground, the OpenPGP ( RFC 2440 ) specification inspires the basic key managing techniques in eCryptfs. This includes the common process of utilizing a hierarchy of keys when executing cryptanalytic operations.

More information can be found at eCryptfs Homepage. [[ 8 ]]

Evaluation Standards

The rating standards of the assorted Crypto-Systems are as follows.

Operating System Support

Portability of Crypto-System

Licensing Mode/Copyrights

The Operating Manner

Mode of Encryption & A ; Decryption

Implementation Quality

Installation and Management of Crypto-System

Algorithms and Key Lengths supported

Data Recoverability ( in the event of the loss of user ‘s key )

Configurable entree control mechanism for cryptanalytic faculty

Acceptable Performance

Swap Space Encryption

Key Management facets

Evaluation Platform

Hardware

The rating of the package is under the premise that DSTA will be running a workstation based on Intel-x 86 ( 32 spot ) dual-core processor platforms with at least 2GB of memory.

Software

Operating Systems used in our testing is Fedora Core 10 ( 32 spot ) for the Linux platform and Windows Vista Ultimate ( 32 spot ) and Windows 7 Ultimate ( 32 spot ) for the Windows platform.

Operating System Support

Based on the latest version of the Crypto-Systems used [[ 9 ]] , these are the list of Operating Systems that the Crypto-Systems support.

Operating System

DM-Crypt

DiskCryptor

TrueCrypt

eCryptfs

Windows

Ten

Linux ( Kernel v2.4 and above )

Ten

Macintosh

Ten

Ten

Ten

Legend

Operating System

Version

Service Pack

Bitness

Windows

2000

SP0-SP4

32

XP

SP0-SP3

32

Waiter 2003

SP0-SP2

32

View

SP0-SP2

32, 64

Waiter 2008

SP0-SP2

32, 64

7

32, 64

Server 2008 R2

64

Macintosh

Mac OS X 10.4

Tiger

Mac OS X 10.5

Leopard

Mac OS X 10.6

Snow Leopard

Using LUKS Extension

DM-Crypt/CryptSetup

There is a particular 3rd party characteristic for DM-Crypt. By utilizing the LUKS ( Linux Unified Key Setup ) extension, DM-Crypt encrypted drives/partitions/files can be read and written to on the Windows platform via a 3rd party package called, FreeOTFE ( Free on the Fly Encryption ) .

The existent creative activity of a DM-Crypt encrypted volume nevertheless has to be done on Linux. It can non be encrypted in Windowss. Merely drives/partitions/files encrypted in Linux with LUKS extension can be read/seen in Windowss or copied to Windowss by utilizing FreeOTFE. It supports all versions of MS Windows from Windows 2000 onwards ( including Windows 7 ) , and Windows Mobile 2003 and subsequently ( including Windows Mobile v6.5 ) .

LUKS is the first cross-platform criterion for crystalline difficult disc encoding and is a specification for how encrypted content is stored in the filesystem, which makes it possible to construct LUKS-compatible tools for any OS. [[ 10 ]]

FreeOTFE can be used in “ portable manner ” , which allows it to be kept on a USB thrust or other portable media, together with its encrypted information, and carried about. This allows it to be used underA Microsoft Windows without installing of the complete plan to “ mount ” and entree the encrypted informations through a practical disc.

It requires put ining drivers to make practical discs. Like most unfastened beginning package which uses device drivers the user must enable trial sign language when run under Windows Vista x64 and Windows 7 x64 systems.

How it works:

On the Ubuntu side:

Grab cryptsetup and cryptmount: A sudo apt-get install cryptsetup cryptmount

Wipe the disc or do some dividers: A sudo cfdisk /dev/sdbA [ NOTE: look into your thrust ‘s existent way with dmesg as you do n’t desire to be pass overing something like your primary thrust ]

Create an encrypted divider: A sudo luksformat /dev/sdbA [ NOTE: choice a passphrase that you can retrieve because if you forget it snog your informations adieu ]

On the Windows side:

Plug in the USB thrust and travel to Computer Management & gt ; & gt ; Disk Management, happen the thrust, and take the assigned thrust missive, FreeOTFE will delegate a free missive to the thrust when it mounts it

Unzip it into a directory and get down it in Portable Mode

File & gt ; & gt ; Linux Volume & gt ; & gt ; Mount divider and come in your passphrase[ 11 ]

For Cryptsetup, the tool is straightforward to utilize, but unluckily works on the partition-level merely, so you can non merely make an encrypted directory inside your place booklet and travel it with easiness, as TrueCrypt and eCryptfs permit.A[ 12 ]

2 ) Crypto-System Portability

PortabilityA is one of the cardinal constructs ofA high-ranking scheduling. Portability is theA softwareA codebase characteristic to be able to recycle the bing codification alternatively of making new codification when traveling package from an environment to another. The requirement for portability is the generalizedA abstractionA between the application logic andA system interfaces. When one is aiming several platforms with the same application, portability is the cardinal issue for development cost decrease.[ 13 ]

TrueCrypt

Portability for TrueCrypt is standard as it supports the 3 major runing systems. Both 32 spot and 64 spot OS of the Windows household are supported. For Mac users, Mac OS X 10.4 Tiger or newer is needed to run TrueCrypt. For the Linux community, every bit long as the meat version is 2.4 and supra, TrueCrypt is supported. It does non back up floppy discs. TrueCrypt is able to run from an external device without being installed on the machine alternatively, running an application called PortableApps from the external thrust, transporting it everyplace you go. TrueCrypt has both command-line interface and a GUI client. TrueCrypt does n’t let coding an bing booklet ; you can merely make a new volume and transcript bing content into it.[ 14 ]

Operating Systems

Service Pack

Bitness

2000

SP0-SP4

32

XP

SP0-SP3

32

Waiter 2003

SP0-SP2

32

View

SP0-SP2

32, 64

Waiter 2008

SP0-SP2

32, 64

7

32, 64

Server 2008 R2

64

Mac OS X 10.4

Tiger

Mac OS X 10.5

Leopard

Mac OS X 10.6

Snow Leopard

Linux

Kernel 2.4,2.6 & A ; above

32bit,64bit

TrueCrypt has both command-line interface and a GUI client.

You must besides pre-choose the entire size of the volume — this is one of TrueCrypt ‘s weak points ; it creates the full volume at a fixed size that can non be expanded if necessary subsequently. In add-on to that TrueCrypt does non let coding an bing booklet ; the lone manner to work out the job is to make a new volume and transcript bing content into it.[ 15 ]

More information can be found at ( TrueCrypt Foundation, 2010 )

3 ) Licensing Mode / Copyrights

DM-Crypt/CryptSetup

hypertext transfer protocol: //www.gnu.org/licenses/old-licenses/gpl-2.0.html

DiskCryptor

hypertext transfer protocol: //www.gnu.org/licenses/gpl-3.0.html

TrueCrypt

hypertext transfer protocol: //www.truecrypt.org/legal/license

eCryptfs

hypertext transfer protocol: //www.gnu.org/licenses/gpl-2.0.html

4 ) Operating Manner

What is an Operating Manner?

The solutions to supply informations security in the signifier of cryptanalytic filesystems in the meat infinite are chiefly based on two attacks. Volume encoding and Filesystem flat encoding. In volume encoding attack, the informations written to the storage device mounted as a volume is encrypted as a whole. A individual cryptanalytic key is used to code both informations and metadata of all the files over the full storage device. Filesystem flat encoding attack is used to code filesystem objects ( files, directories and metadata ) , instead than the storage device as a whole. Different keys are used in this attack for different filesystem objects.

Operating Mode Support ( Encryption Layer )

Full Disk Enc ( Whole Disk )

Partition Enc

Filesystem Level Enc ( Folder or File )

Volume Enc

Hidden Volume Enc

DM-Crypt

?

DiskCryptor

Ten

Ten

Ten

TrueCrypt

eCryptfs

Ten

Ten

Ten

Ten

A filesystem ( frequently besides written as “ filesystem ” ) is a method of hive awaying and forming computing machine files and their informations. Basically, it organizes these files into a database for the storage, organisation, use, and retrieval by the computing machine ‘s operating system.

Full disc encoding ( or whole disc encoding ) uses disk encoding package or hardware to code every spot of informations that goes on a disc or disc volume. Full disc encoding prevents unauthorised entree to informations storage. The term “ full disc encoding ” is frequently used to mean that everything on a disc is encrypted, including the bootable operating system dividers. However they must still go forth the maestro boot record ( MBR ) unencrypted. There are hardware-based full disc encoding and intercrossed full disc encoding systems that can truly code the full boot disc, including the MBR.

Partition EncryptionA package normally works on basic discs. It is a more flexible manner of coding informations, because it allows the user to open ( enter watchword and acquire entree to ) different encrypted dividers independently. Note that if a divider occupies the whole difficult thrust, it works for the user as Whole Disk Encryption.

Filesystem-level encoding, frequently called file or booklet encoding, is a signifier of disc encoding where single files or directories are encrypted by the filesystem itself. This is in contrast toA full disc encryptionA where the full divider or disc, in which the filesystem resides, is encrypted.

Volume Encryption package works with volume as with a individual part of informations. Volume is ever in one of the two definite provinces: if watchword is non entered, the whole volume is non accessible. If the user enters the proper watchword and opens the volume, all its parts, even stored on different difficult thrusts, become accessible. A volume shops a complete filesystem construction and a complete tree of the user ‘s files. As in the modern universe individual volume shops informations scattered on a figure of physical discs, it is more convenient and safe to pull off a volume, instead than work with every physical thrust individually. Note that if Volume Encryption package encrypts a volume dwelling of a individual divider, for the user it will give the same consequence as Partition Encryption package. If a individual divider occupies the whole difficult thrust, Volume Encryption will be equal both to Whole Disk Encryption and Partition Encryption.

The followers are some benefits of full disc encoding:

About everything including the barter infinite and the impermanent files is encrypted. Coding these files is of import, as they can uncover confidential informations.

With full disc encoding, the determination of which single files to code is non left up to users ‘ discretion. This is of import for state of affairss in which users might non desire or might bury to code sensitive files.

Support for pre-boot hallmark.

Immediate informations devastation, as merely destructing the cryptanalysis keys renders the contained informations useless. However, if security towards future onslaughts is a concern, purging or physical devastation is advised.

The advantages of filesystem-level encoding include:

Flexible file-based cardinal direction so that each file can be and normally is encrypted with a separate encoding key.

Individual direction of encrypted files. E.g. incremental backups of the person changed files even in encrypted signifier, instead than backup of the full encrypted volume.

Access control can be enforced through the usage of public-key cryptanalysis, and the fact that cryptanalytic keys are merely held in memory while the file that is decrypted by them is help open.

( Volume Encryption, 2010 )

Swap Partition

A barter divider is a placeq on the thrust where practical random-access memory resides, leting the meat to easy utilize disc storage for informations that does non suit into the physical Ram. The general regulation for barter divider size was 2x the sum of physical RAM. Over clip as computing machines have gained of all time larger memory capacities, this regulation has become progressively deprecated.

DM-Crypt/CryptSetup

DM-Crypt is a divider based cryptanalytic faculty. Rather than coding a whole device, it really merely encrypts assorted dividers on the block device. It is besides able to code the full disc dividers including the root filesystem which is more complex. However, Linux does n’t supply a tool to assist code the root filesystem during the install or subsequently. You ‘ll hold to hold some hands-on constellation. DM-Crypt besides supports coding a file-based volume when used with losetup public-service corporation included with all major Linux distributions. It works by first making a file to keep the users informations and subsequently mounting it on a loop device utilizing the device plotter substructure.

The cons of DM-Crypt are all informations that is written to the disc underneath ( including metadata ) is encrypted. It lacks an advanced cardinal direction strategy due to the use of merely a individual key for the whole volume. Incremental backups are difficult to implement. These restrictions of dm-crypt restrict its usage to a smaller section of users, instead than it being used in big corporate where file sharing and incremental back-ups happen on a regular basis.

DiskCryptor

DiskCryptor is able to code full difficult thrust dividers, including the system divider every bit good as brassy thrusts or single dividers in existent clip without impacting public presentation or destructing any bing informations. It can besides make encrypted CDs/DVDs ( through the usage of disc images.ISO files ) . Other encoding options include coding the barter infinite and hibernation files ( if hibernation is supported on the OS ) .

TrueCrypt

TrueCrypt supports encoding of system dividers and storage devices such as thumbdrive or other removable media. Furthermore it allow users to make a encrypted container to hive away sensitive informations. TrueCrypt uses Block Device Encryption[ 16 ]. TrueCrypt supports a construct called plausible deniability, by leting a individual hidden volume to be created in another volume. In add-on the Windows version of TrueCrypt supports two sorts of plausible deniability. One sort of it is Hidden volumes and concealed operating systems. Another is that TrueCrypt besides has the ability to make a concealed operating system. TrueCrypt besides uses a public API to code hibernation and clang shit files in a safe documented manner.[ 17 ]

eCryptfs

eCryptfs uses a Stacked Filesystem encoding. This package merely performs encoding on per-file footing. Each of the files are encrypted with its ain File Encryption Key ( FEK ) that is so wrapped by the File Key Encryption Key ( FKEK ) derived from the mount-wide key ( either utilizing a passphrase or external cardinal faculties ) . eCryptfs is stackable and can be used on top of an bing filesystem ; requires no particular on-disk storage allotment attempt. eCryptfs allows selective encoding of the contents of merely the sensitive files. eCryptfs can non maintain all filesystem metadata confidential. Since stacked filesystem encrypts on a per-file footing, aggressors will cognize the approximative file sizes. Individual encrypted files can be accessed transparently by applications ; no extra work needed on the portion of applications before traveling the files to another location. However it is non designed to protect swap infinite.

5 ) Encoding and Decryption Modes

What are Encryption and Decryption Modes? With a symmetric key block cypher algorithm, the same plaintext block will ever code to the same ciphertext block when the same symmetric key is used. If the multiple blocks in a typical message are encrypted individually, an antagonist could easy happen certain sorts of informations form in the plaintext, such as repeated blocks which would be evident in the ciphertext.

Encoding manners have been defined to turn to this job by uniting the basic cryptanalytic algorithm with feedback regulations and a variable low-level formatting values ( normally known as low-level formatting vectors ) for the information derived from the cryptanalytic operation.

Listed below are the operating modes that the assorted crypto-systems support.

Encoding Mode

Complete blood count

CFB

OFB

CTR

LRW

Crosstalk

DM-Crypt /CryptSetup

Ten

Ten

Ten

Disk Cryptor

Ten

Ten

Ten

Ten

Ten

True Crypt

Ten

Ten

Ten

Ten

Ten

eCryptfs

Ten

Ten

Ten

Ten

Ten

Legend

Complete blood count

Cipher Block Chaining

CFB

Cipher Feedback Mode

OFB

Output Feedback Mode

CTR

Counter Mode

LRW

It is derived from the names Liskov, Rivest, Wagner, tweakable narrow-block manner – the writers of the encoding manner.

Crosstalk

XEX-based Tweaked CodeBook manner ( TCB ) with CipherText Stealing ( CTS )

Cipher Block Chaining ( CBC )

The CBC manner is a confidentiality manner whose encoding procedure features the combine ( chaining ) of the plaintext blocks with the old ciphertext blocks. The CBC manner requires an IV ( Initialization Vector ) to unite with the first plaintext block. The IV need non be secret, but it must be unpredictable. Below is a simple diagram of how CBC works.

Legend

CIPHK,

Encoding Algorithm ( E.g. 3DES, AES )

CIPH-1K

Decoding Algorithm ( E.g. 3DES, AES )

aS•

Exclusive Or ( It is a type ofA logical disjunctionA on twoA operandsA that consequences in a value ofA trueA if precisely one of the operands has a value of true. )

More information can be found at NIST Special Publication 800-38A

( Morris Dworkin, 2001 )

Liskov, Rivest, Wagner ( LRW )

LRW is a tweakable narrow block encoding cypher that acts on “ narrow ” blocks of 16 bytes ( 128bits ) . Narrow-block algorithms operate on comparatively little parts of informations and hence have the advantage of more efficient hardware execution.

Tweak block chaining ( TBC ) is similar to code block chaining ( CBC ) . An initial pinch T0 plays the function of the low-level formatting vector ( IV ) for CBC. Each consecutive message block Mi is encrypted under control of the encoding cardinal K and a pinch TiA?1,

Legend

M1

Plaintext

T0

Pinch

EK

Encoding Algorithm ( E.g. 3DES, AES )

More info can be found at ( Moses Liskov, Ronald L. Rivest, and David Wagner )

From the twelvemonth 2004 to the twelvemonth 2006, bill of exchanges of the P1619 criterions were usingA AESA inA LRW manner. In theA Aug 30, 2006A meeting of the SISWG, a straw canvass showed that most members would non O.K. P1619 “ as is ” . Consequently, LRW-AES has been replaced by the XEX-AESA tweakable block cypher in P1619.0 DraftA 7 ( and renamed to XTS-AES in DraftA 11 ) .

Beginning from ( Wikipedia )

XEX-based Tweaked CodeBook manner ( TCB ) with CipherText Stealing ( CTS ) ( XTS )

XTS-AES is presently considered by SISWG for the IEEE P1619 Standard for Cryptographic Protection of Data on Block-Oriented Storage Devices.

Crosstalk is based on XEX ( Xor-Encrypt-Xor ) , which was designed by Rogaway to let efficient processing of back-to-back blocks ( with regard to the cypher used ) within one informations unit ( e.g. a disc sector ) . It besides uses cipher text stealing to manage sectors non incorporating a figure of bytes equal to an whole number multiple of the AES block size. XTS uses a tweak operand, which is similar to an low-level formatting vector ( IVs ) . However an IV must be random, whereas a pinch does n’t hold to be.

The pinch aims to supply variableness of the ciphertext, whereas the cardinal provides security against an adversary retrieving the plaintext.

From IEEE P1619 ( Storage Working Group, 2007 )

Ciphertext Stealing ( CTS )

Ciphertext Stealing is the technique of changing processing of the last two blocks ofA plaintext, ensuing in a reordered transmittal of the last two blocks of ciphertext and no ciphertext enlargement. This is accomplished by embroidering the last plaintext block ( which is perchance uncomplete ) with the high order spots from the 2nd to last ciphertext block ( stealing the ciphertext from the 2nd to last block ) . The ( now full ) last block is encrypted, and so exchanged with the 2nd to last ciphertext block, which is so truncated to the length of the concluding plaintext block, taking the spots that were stolen, ensuing in ciphertext of the same length as the original message size.

More info can be found at IEEE P1619 ( Storage Working Group, 2007 )

DM-Crypt/CryptSetup

DM-Crypt supports 3 manners of operation. These manners are CBC, LRW and XTS. CBC is still the default coding manner for encoding, nevertheless it is non recommended due to a exposure to watermarking onslaughts. As such, the user should ever provide the parametric quantity to stipulate the manner of operation, algorithm and cardinal length to avoid such exposures.

Watermarking Attack

It is an onslaught onA disc encryptionA methods where the presence of a specially crafted piece of informations ( E.g. aA decoyA file ) can be detected by an aggressor without cognizing the encryptionA key. More information pertaining to watermarking onslaughts can be found at ( Watermarking Attack Wikipedia )

DiskCryptor

DiskCryptor merely employs XTS as the manner of operation for encoding and decoding. On multiprocessor systems encoding operations can run in analogue, where DiskCryptor automatically chooses optimum parallel manner based on system constellation.

( Ntldr & A ; Jet-Phryx, 2010 )

TrueCrypt

TrueCrypt uses XTS for encrypted dividers, thrusts and practical volumes. Crosstalk makes usage of two different keys ( independent keys ) , normally generated by dividing the supplied block cypher ‘s key in half. While XEX manner uses a individual key for two different intents. Crosstalk has to be created with TrueCrypt version 5.0 and subsequently.[ 18 ]CBC w/ predictable IVs and LRW is besides used but with legacy support ( can be use older versions of TrueCrypt ) .[ 19 ]For CBC, merely TrueCrypt versions 1.0 through 4.0. As for LRW, merely TrueCrypt versions 4.1 through 4.3a.

eCryptfs

Mode of encoding for eCryptfs is Stacked Filesystem Encryption. Unlike most of the other cryptanalytic package, eCryptfs is really a existent filesystem. This allows the user to code on top of an bing divider unlike Block Device Encryption which creates a physical block device. Merely supports CBC with secret IVs. CBC with secret Four: The CBC manner where low-level formatting vectors are statically derived from the encoding key and sector figure. The IVs are secret, but they are re-used with overwrites. Methods for this include ESSIV and encrypted sector Numberss ( CGD ) .

Low-level formatting Vector Support

An Initialization Vector ( IVs ) is a continuously altering figure ( block of spots ) used in combination with a secret key to code informations. Low-level formatting Vectors are used to forestall sequence of text that is indistinguishable to a old sequence from bring forthing the same exact ciphertext when encrypted. Therefore doing it more hard for a hacker utilizing aA dictionary attackA to happen forms and interrupt a cypher. For illustration, a sequence might look twice or more within the organic structure of a message. If there are perennial sequences in encrypted informations, an aggressor could presume that the corresponding sequences in the message were besides indistinguishable. The IV prevents the visual aspect of matching duplicate character sequences in theA ciphertext.A

The size of the IV depends on the encoding algorithm and on the cryptanalytic protocol ( E.g. TLS ) in usage and is usually every bit big as the block size of the cypher or every bit big as the encoding key. The IV must be known to the receiver of the encrypted information to be able to decode it. If the IV is chosen atA random, the cryptanalyst must take into consideration the chance of hits, and if an incremental IV is used as aA time being ( figure used one time ) , the algorithm ‘s opposition to related-IV onslaughts must besides be considered.

Summary of cypher manners.

Name

Parallelisable

Four Requirements

Remarks

Complete blood count

No

Salt

CFB

No

Salt

OFB

No

Time being

Unsuitable for difficult disc encoding

CTR

Yes

Drawn-out Requirements

Unsuitable for difficult disc encoding

LRW

Yes

Pinch

Replaced by Crosstalk

Crosstalk

?

Salt or Nonce

SISWG Candidate

Legend

Time being

A figure used merely one time.

Pinch

A non-random predictable value that can be reused.

Salt

Generated indiscriminately.

ESSIV

Encrypted Salt-Sector Initialization Vector

A alone unpredictable point.

5 ) Key Manageability

Uses PBKDF2 ( Password-Based Key Derivation Function ) is a cardinal derivation map that is portion of RSA Laboratories ‘ Public-Key Cryptanalysis Standards ( PKCS ) series, specifically PKCS # 5 v2.0, besides published as Internet Engineering Task Force ‘s RFC 2898. It replaces an earlier criterion, PBKDF1, which could merely bring forth derived identify up to 160 spots long.

DM-Crypt

Empty.

DiskCryptor

Empty.

TrueCrypt

TrueCrypt offers no centralised key direction ( creates, distributes and shops encryption keys while keeping the organisation ‘s ability to retrieve informations ) or cardinal escrow services ( keeps encoding keys used in cryptography-based communicating ) . As such, a doomed or forgotten watchword will ensue in irreversible informations loss.

eCryptfs

In footings of per-file cardinal direction, eCryptfs uses methods of PGP ( Pretty Good Privacy ) and takes the obvious and conceptually fiddling measure of using those methods within filesystem service in the meat.

6 ) Crypto algorithm ( s ) and cardinal length supported

List of crypto algorithm ( s ) supported.

DM-Crypt

DiskCryptor

TrueCrypt

eCryptfs

DES

Ten

Ten

Ten

Ten

3DES

Ten

Ten

Ten

AES

Blowfish

Ten

Ten

Twofish

Snake

Ten

Ten

Cast5

Ten

Ten

Ten

Cast6

Ten

Ten

Ten

Ternary DESA ( 3DES ) is the common name for the Triple Data Encryption Algorithm ( TDEA ) A block cypher, which applies theA Data Encryption StandardA ( DES ) cypher algorithm three times to each information block. Because of the handiness of increasing computational power, theA cardinal sizeA of the original DES cypher was going capable to brute force onslaughts ; Triple DES was designed to supply a comparatively simple method of increasing the cardinal size of DES to protect against such onslaughts, without planing a wholly new block cypher algorithm.

Advanced Encryption StandardA ( AES ) is a symmetric-keyA encoding criterion adopted by theA U.S. authorities. The standard comprises threeA block cyphers, AES-128, AES-192 and AES-256, adopted from a larger aggregation originally published asA Rijndael.A Each of these cyphers has a 128-bit block size, withA cardinal sizes of 128, 192 and 256 spots, severally. The AES cyphers have been analyzed extensively and are now used worldwide, as was the instance with its predecessor, A theA Data Encryption Standard ( DES ) .

BlowfishA is aA keyed, A symmetricA block cypher, designed in 1993 byA Bruce SchneierA and included in a big figure of cypher suites and encoding merchandises. Blowfish provides a good encoding rate in package and no effectiveA cryptanalysisA of it has been found to day of the month. However, theA Advanced Encryption StandardA now receives more attending.

InA cryptanalysis, A TwofishA is aA symmetric key block cipherA with aA block sizeA of 128A bitsA and key sizesA up to 256 spots. It was one of the five finalists of theA Advanced Encryption Standard competition, but was non selected for standardization. Twofish is related to the earlier block cipherA Blowfish.

Like otherA AESA entries, Serpent has aA block sizeA of 128 spots and supports aA cardinal sizeA of 128, 192 or 256 spots. TheA cipherA is a 32-roundA substitution-permutation web runing on a block of four 32-bitA words. Each unit of ammunition applies one of eight 4-bit to 4-bitA S-boxesA 32 times in analogue. Serpent was designed so that all operations can be executed inA analogue, utilizing 32 1-bit pieces. This maximizes correspondence, but besides allows usage of the extended cryptanalysisA work performed onA DES.

InA cryptanalysis, A CAST-128A ( alternativelyA CAST5 ) is a block cipherA used in a figure of merchandises, notably as the defaultA cipherA in some versions ofA GPGA andA PGP. It has besides been approved forA CanadianA authorities usage by the Communications Security Establishment. The algorithm was created inA 1996A byA Carlisle AdamsA andA Stafford TavaresA utilizing theA CASTA design process ; another member of the CAST household of cyphers, A CAST-256A ( a former AESA campaigner ) was derived from CAST-128. Harmonizing to some beginnings, the CAST name is based on theA initialsA of its discoverers, thoughA Bruce SchneierA reports the writers ‘ claim that “ the name should raise up images of entropy ” ( Schneier, 1996 ) .

InA cryptanalysis, A CAST-256A ( orA CAST6 ) is aA block cypher published in JuneA 1998. It was submitted as a campaigner for theA Advanced Encryption StandardA ( AES ) ; nevertheless, it was non among the fiveA AES finalists. It is an extension of an earlier cypher, A CAST-128 ; both were designed harmonizing to the “ CAST ” design methodological analysis invented byA Carlisle Adams andA Stafford Tavares.A Howard HeysA andA Michael Wiener besides contributed to the design.

Glossary

CBC – Cipher block chaining ( CBC ) is a common chaining manner in which the old block ‘s ciphertext is Xored with the current block ‘s plaintext before encoding.

Block Cipher – It is a symmetric key cypher runing on fixed-length groups of spots, called blocks, with an changeless transmutation. A block cypher encoding algorithm might take ( for illustration ) a 128-bit block of plaintext as input, and end product a corresponding 128-bit block of ciphertext.

Block device – Block particular files or block devices correspond to devices through which the system moves informations in the signifier of blocks. These device nodes frequently represent addressable devices such as difficult discs, CD-ROM drives, or memory-regions.

Crypto API – It is a cryptanalysis model in the Linux meat, for assorted parts of the meat that trade with cryptanalysis, such as IPSec and DM-crypt. It was introduced in meats version 2.4.12 and has since expanded to include basically all popular block cyphers and hash maps.

Cryptmount – It is a package tool for pull offing encrypted filesystems under the GNU/Linux household of runing systems. It uses the device plotter and DM-Crypt substructure to supply crystalline encoding of filesystems stored in disc dividers or within ordinary files.

Cryptoloop – It is a disk encoding faculty for Linux which relies on the Crypto API in the 2.6 Linux meat series.

Cryptsetup – It is used to handily setup DM-Crypt managed block devices under Linux.

Device mapper – A generic model used to map one block device into another.

ESSIV – Encrypted Salt-Sector Initialization Vector ( ESSIV ) is a method for bring forthing low-level formatting vectors for block encoding to utilize in disc encoding.

LRW – A tweakable narrow-block encoding cypher ( LRW ) is an instantiation of the manner of operations introduced by Liskov, Rivest, and Wagner.

LUKS – Linux Unified Key Setup or LUKS is a disk-encryption specification created by Clemens Fruhwirth and originally intended for Linux.

Water-marking onslaught – It is an onslaught on disc encoding methods where the presence of a specially crafted piece of informations ( e.g. , a steerer file ) can be detected by an aggressor without cognizing the encoding key.

XOR – The logical operation sole disjuncture, besides called sole or ( symbolized XOR, EOR, EXOR ) , is a type of logical disjuncture on two operands that consequences in a value of true if precisely one of the operands has a value of true. A simple manner to province this is “ one or the other but non both. ”

XTS – It is XEX-based Tweaked CodeBook manner ( TCB ) with Ciphertext Stealing ( CTS )