Difference between pages "Encase image file format" and "BitLocker Disk Encryption"

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The Encase image file format is used by [[EnCase]] used to store various types of digital evidence e.g.
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'''BitLocker Disk Encryption''' (BDE) is [[Full Volume Encryption]] solution by [[Microsoft]] first included with the Enterprise and Ultimate editions of [[Windows|Windows Vista]]. It is also present in [[Windows|Windows 7]] along with a system for encrypting removable storage media devices, like [[USB]], which is called BitLocker To Go. Unlike previous versions of BitLocker, BitLocker To Go allows the user to protect volumes with a password or smart card.
* disk image (physical bitstream of an acquired disk)
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* volume image
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* memory
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* logical files
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== History ==
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== BitLocker ==
Expert Witness (for Windows) was the original name for EnCase (dating back to 1998). More info about this can be found on the Internet Archive [http://web.archive.org/web/19980504153628/http://guidancesoftware.com/] including a demo of the original software [http://web.archive.org/web/19980504153759/http://guidancesoftware.com/data/ewsetup.exe].
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Volumes encrypted with BitLocker will have a different signature than the standard [[NTFS]] header. Instead, they have in their volume header (first sector): <tt>2D 46 56 45 2D 46 53 2D</tt> or, in ASCII, <tt>-FVE-FS-</tt>.
  
(presumably) the product was renamed because it intruded the Expert Wittness trademark held by ASR Data [http://www.asrdata.com/wp-content/themes/asr/pdf/ruling.pdf].
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These volumes can be identified by the BitLocker GUID/UUID: 4967d63b-2e29-4ad8-8399-f6a339e3d00.
  
The Encase image file format therefore is also referred to as the Expert Witness (Compression) Format.
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The actual data on the encrypted volume is protected with either 128-bit or 256-bit [[AES]] and optionally diffused using an algorithm called Elephant. The key used to do the encryption, the Full Volume Encryption Key (FVEK) and/or TWEAK key, is stored in the BitLocker metadata on the protected volume. The FVEK and/or TWEAK keys are encrypted using another key, namely the Volume Master Key (VMK). Several copies of the VMK are also stored in the metadata. Each copy of the VMK is encrypted using another key, also know as key-protector key. Some of the key-protectors are:
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* TPM (Trusted Platform Module)
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* Smart card
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* recovery password
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* start-up key
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* clear key; this key-protector provides no protection
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* user password
  
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BitLocker has support for partial encrypted volumes.
  
Currently there are 2 versions of the format:
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== BitLocker To Go ==
* version 1 is (reportedly) based on [[ASR Data's Expert Witness Compression Format]]
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Volumes encrypted with BitLocker To Go will have a hybrid encrypted volume, meaning that part of the volume is unencrypted and contains applications to unlock the volume and the other part of the volume is encrypted. The "discovery drive" volume contains BitLocker To Go Reader to read from encrypted volumes on versions of Microsoft [[Windows]] without BitLocker support.
* version 2 was introduced in EnCase 7, for which a format specification (at least non-encrypted Ex01) is available, but requires registration.
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The libewf project indicates that the January 2012 version of the version 2 format specification, besides Lx01 not being specified, is sufficient to read non-encrypted Ex01 files.
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== manage-bde ==
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To view the BitLocker Drive Encryption (BDE) status on a running Windows system:
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<pre>
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manage-bde.exe -status
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</pre>
  
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To obtain the recovery password for volume C:
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<pre>
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manage-bde.exe -protectors -get C: -Type recoverypassword
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</pre>
  
Although the format specification is not complete, at the moment Guidance Software is working on an update. This will not include:
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Or just obtain the all “protectors” for volume C:
* encrypted Ex01
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<pre>
* Lx01
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manage-bde.exe -protectors -get C:
 
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</pre>
 
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So in contrast to other claims [http://tech.groups.yahoo.com/group/linux_forensics/message/3555] both versions of the EWF file format are:
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* proprietary
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* partially open specification
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For more information about these definitions see: [[File formats]]
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== Version 1 ==
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The media data can be stored in multiple evidence files, which are called segment files.
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Each segment file consist of multiple sections, which has a distinct section start definition containing a section type.
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Up to EnCase 5 the segment file were limited to 2 GiB, due to the internal 31-bit file offset representation. This limitation was lifted by adding a base offset value in EnCase 6.
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EnCase allows to store the data compressed either using a fast or best level of the deflate compression method.
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EnCase 7 no longer distinguishes between fast or best compression and just provides for either uncompressed or compressed.
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Besides digital evidence the evidence files, or segment files, contain a header containing case information.
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The case information which entails date and time of acquisition, an examiner's name, notes on the acquisition, and an optional password.
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* In EnCase 3 the case information header is stored in the "header" section, which is defined twice within the file and contain the same information.
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* As of EnCase 4 an additional "header2" section was added. The "header" section now appears only once, but the new "header2" section twice.
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The format adds error detection by storing the data with checksums (Adler32), for both the metadata as the data blocks, which are by default 64 x 512 byte sectors (32 KiB).
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As of EnCase 5 the number of sectors per block (chunk) can vary.
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EnCase 3F introduced an "error2" section that it uses to record the location and number of bad sector chunks. The way it handles the sections it can't read is that those areas are filled with zero.
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Then EnCase displays to the user the areas that could not be read when the image was acquired. The granularity of unreadable chunks appears to be 32K.
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As of EnCase 5 the granularity of unreadable chunks can vary.
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EnCase 3 can store a one-way hash of the data. For a bitstream it does so by calculating e.g. a MD5 hash of the original media data and adds a hash section to the last of the segment file.
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As of EnCase 6 the option to store a SHA1 hash was added.
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EnCase 5 and later have the option to store '''single files''' into the EnCase Logical Evidence File (LEF) or EWF-L01.
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This format changed slightly in EnCase 6 and 7.
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== Version 2 ==
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In EnCase 7 the EWF format was succeeded by the EnCase Evidence File Format Version 2 (EWF2-EX01 and EWF2-LX01).
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EWF2-EX01 is at it's lower levels a different format then EWF-E01 and provides support for:
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* bzip2 compression
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* direct encryption (AES-256) of the section data
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The same features are added to the new logical evidence file format (EWF2-LX01) with the exception of encryption.
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The actual encryption method and corresponding key derivation are, currently, not open.
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EWF2-EX01, EWF2-LX01 are not backwards compatible with previous EnCase products.
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== See Also ==
 
== See Also ==
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* [[BitLocker:_how_to_image|BitLocker: How to image]]
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* [[Defeating Whole Disk Encryption]]
  
* [[ASR Data's Expert Witness Compression Format]]
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== External Links ==
* [[EnCase]]
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== External Links ==  
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* [http://www.nvlabs.in/archives/1-NVbit-Accessing-Bitlocker-volumes-from-linux.html NVbit : Accessing Bitlocker volumes from linux], 2008
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* Jesse D. Kornblum, [http://jessekornblum.com/publications/di09.html Implementing BitLocker for Forensic Analysis], ''Digital Investigation'', 2009
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* [http://en.wikipedia.org/wiki/BitLocker_Drive_Encryption Wikipedia entry on BitLocker]
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* [http://technet2.microsoft.com/WindowsVista/en/library/c61f2a12-8ae6-4957-b031-97b4d762cf311033.mspx?mfr=true Microsoft's Step by Step Guide]
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* [http://technet.microsoft.com/en-us/windowsvista/aa906017.aspx Microsoft Technical Overview]
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* [http://technet.microsoft.com/en-us/magazine/2009.05.win7.aspx An Introduction to Security in Windows 7]
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* [http://www.microsoft.com/whdc/system/platform/hwsecurity/BitLockerFAQ.mspx Microsoft FAQ]
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* [http://www.microsoft.com/downloads/details.aspx?FamilyID=131dae03-39ae-48be-a8d6-8b0034c92555&DisplayLang=en Microsoft Description of the Encryption Algorithm]
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* [http://secude.com/htm/801/en/White_Paper%3A_Cold_Boot_Attacks.htm Cold Boot Attacks, Full Disk Encryption, and BitLocker]
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* [http://technet.microsoft.com/en-us/library/hh831412.aspx What's New in BitLocker] in Windows 8
  
* [http://www.cfreds.nist.gov/v2/Basic_Mac_Image.html Sample image in EnCase, iLook, and dd format] - From the [[Computer Forensic Reference Data Sets]] Project, the E01 sample image dates from January 2005
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== Tools ==
* [https://googledrive.com/host/0B3fBvzttpiiSMTdoaVExWWNsRjg/Expert%20Witness%20Compression%20Format%20(EWF).pdf Expert Witness Compression Format (EWF)], by the [[libewf|libewf project]], March 2006
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* [http://www.hsc.fr/ressources/outils/dislocker/ dislocker]
* [http://encase-enterprise-blog.guidancesoftware.com/2012/01/2nd-generation-encase-evidence-file.html 2nd Generation EnCase Evidence File Technical Specification now Available], Guidance Software, January 2012
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* [[libbde]]
* Requires registration: [http://www.guidancesoftware.com/DocumentRegistration.aspx?did=1000018246 EnCase Evidence File Format Version 2], Guidance Software, January 2012
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* [http://www.guidancesoftware.com/Document.aspx?did=1000019161 ex01 Example], by [[Guidance Software]], March 2012
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* [https://googledrive.com/host/0B3fBvzttpiiSMTdoaVExWWNsRjg/Expert%20Witness%20Compression%20Format%202%20(EWF2).pdf Expert Witness Compression Format (EWF) version 2], by the [[libewf|libewf project]], July 2012
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[[Category:Forensics File Formats]]
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[[Category:Disk encryption]]
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[[Category:Windows]]

Revision as of 00:44, 15 July 2013

BitLocker Disk Encryption (BDE) is Full Volume Encryption solution by Microsoft first included with the Enterprise and Ultimate editions of Windows Vista. It is also present in Windows 7 along with a system for encrypting removable storage media devices, like USB, which is called BitLocker To Go. Unlike previous versions of BitLocker, BitLocker To Go allows the user to protect volumes with a password or smart card.

BitLocker

Volumes encrypted with BitLocker will have a different signature than the standard NTFS header. Instead, they have in their volume header (first sector): 2D 46 56 45 2D 46 53 2D or, in ASCII, -FVE-FS-.

These volumes can be identified by the BitLocker GUID/UUID: 4967d63b-2e29-4ad8-8399-f6a339e3d00.

The actual data on the encrypted volume is protected with either 128-bit or 256-bit AES and optionally diffused using an algorithm called Elephant. The key used to do the encryption, the Full Volume Encryption Key (FVEK) and/or TWEAK key, is stored in the BitLocker metadata on the protected volume. The FVEK and/or TWEAK keys are encrypted using another key, namely the Volume Master Key (VMK). Several copies of the VMK are also stored in the metadata. Each copy of the VMK is encrypted using another key, also know as key-protector key. Some of the key-protectors are:

  • TPM (Trusted Platform Module)
  • Smart card
  • recovery password
  • start-up key
  • clear key; this key-protector provides no protection
  • user password

BitLocker has support for partial encrypted volumes.

BitLocker To Go

Volumes encrypted with BitLocker To Go will have a hybrid encrypted volume, meaning that part of the volume is unencrypted and contains applications to unlock the volume and the other part of the volume is encrypted. The "discovery drive" volume contains BitLocker To Go Reader to read from encrypted volumes on versions of Microsoft Windows without BitLocker support.

manage-bde

To view the BitLocker Drive Encryption (BDE) status on a running Windows system:

manage-bde.exe -status

To obtain the recovery password for volume C:

manage-bde.exe -protectors -get C: -Type recoverypassword

Or just obtain the all “protectors” for volume C:

manage-bde.exe -protectors -get C:

See Also

External Links

Tools