Difference between pages "Disk Imaging" and "Imager NG Ideas"

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This page is for discussing ideas regarding next-generation (NG) imaging tools.
  
Disk imaging is the process of making a bit-by-bit copy of a disk. Imaging (in more general terms) can apply to anything that can be considered as a bit-stream, e.g. a physical or logical volumes, network streams, etc.
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Note that some of the ideas mentioned can be already used by imaging tools, but the idea of this page is to determine how useful these features could be for next-generation of imaging tools.
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The scope is mainly a software-based imaging tools, but not limited to. Some features might not be doable, because of limitations of certain image file formats.
  
The most straight-forward disk imaging method is reading a disk from start to end and writing the data to a [[:Category:Forensics_File_Formats|Forensics image format]].
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Please, do not delete text (ideas) here. Use something like this:
This can be a time consuming process especially for disks with a large capacity.
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The process of disk imaging is also referred to as disk duplication.
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== Disk Imaging Solutions ==
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This will look like:
See: [[:Category:Disk Imaging|Disk Imaging Solutions]]
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== Common practice ==
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<s>bad idea</s>
It common practice to use a [[Write Blockers|Write Blocker]] when imaging a pyhical disk. The write blocker is an additional measure to prevent write access to the disk.
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Also see: [[DCO and HPA|Device Configuration Overlay (DCO) and Host Protected Area (HPA)]]
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= License =
  
== Error tolerance and recovery ==
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= Features =
...
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* Compression
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* Integrity hash calculations
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* Encryption
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* Error correction (parity)
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* Pre-processing during imaging
  
Also see: [[Piecewise hashing]]
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== Compression ==
 
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* Reduces the amount of data that needs to be written; improved the overall imaging speed.
== Smart imaging ==
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** Hash-based imaging
Smart imaging is a combination of techniques to make the imaging process more intelligent.
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** detection of easy (emtpy-block) and hard (encrypted block) to compress data
* Compressed storage
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** multi-threaded compression
* Deduplication
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** sparse ranges
* Selective imaging
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** de-duplication
* Decryption while imaging
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=== Compressed storage ===
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A common technique to reduce the size of an image file is to compress the data. Where the compression method should be [http://en.wikipedia.org/wiki/Lossless_data_compression lossless].
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On modern computers, with multiple cores, the compression can be done in parallel reducing the output without prolonging the imaging process.
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Since the write speed of the target disk can be a bottleneck in imaging process, parallel compression can reduce the total time of the imaging process.
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[[Guymager]] was one of the first imaging tools to implement the concept of multi-process compression for the [[Encase image file format]]. This technique is now used by various imaging tools including [http://www.tableau.com/index.php?pageid=products&model=TSW-TIM Tableau Imager (TIM)]
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Other techniques like storing the data sparse, using '''empty-block compression''' or '''pattern fill''', can reduce the total time of the imaging process and the resulting size of new non-encrypted (0-byte filled) disks.
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=== Deduplication ===
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Deduplication is the process of determining and storing data that occurs more than once on-disk, only once in the image.
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It is even possible to store the data once for a corpus of images using techniques like hash based imaging.
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=== Selective imaging ===
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Selective imaging is a technique to only make a copy of certain information on a disk like the $MFT on an [[NTFS]] volume with the necessary contextual information.
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[[EnCase]] Logical Evidence Format (LEF) is an example of a selective image; although only file related contextual information is stored in the format by [[EnCase]].
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=== Decryption while imaging ===
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Encrypted data is worst-case scenario for compression. Because the encryption process should be deterministic a solution to reduce the size of an encrypted image is to store it non-encrypted and compressed and encrypt it on-the-fly if required. Although this should be rare since the non-encrypted data is what undergoes analysis.
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== Also see ==
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* [[:Category:Forensics_File_Formats|Forensics File Formats]]
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* [[Write Blockers]]
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* [[Piecewise hashing]]
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* [[Memory Imaging]]
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== External Links ==
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* [http://www.tableau.com/pdf/en/Tableau_Forensic_Disk_Perf.pdf Benchmarking Hard Disk Duplication Performance in Forensic Applications], by [[Robert Botchek]]
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=== Hash based imaging ===
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* [http://www.dfrws.org/2010/proceedings/2010-314.pdf Hash based disk imaging using AFF4], by [[Michael Cohen]], [[Bradley Schatz]]
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[[Category:Disk Imaging]]
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Revision as of 01:39, 6 September 2012

This page is for discussing ideas regarding next-generation (NG) imaging tools.

Note that some of the ideas mentioned can be already used by imaging tools, but the idea of this page is to determine how useful these features could be for next-generation of imaging tools. The scope is mainly a software-based imaging tools, but not limited to. Some features might not be doable, because of limitations of certain image file formats.

Please, do not delete text (ideas) here. Use something like this:

<s>bad idea</s>
:: good idea

This will look like:

bad idea

good idea

License

Features

  • Compression
  • Integrity hash calculations
  • Encryption
  • Error correction (parity)
  • Pre-processing during imaging

Compression

  • Reduces the amount of data that needs to be written; improved the overall imaging speed.
    • Hash-based imaging
    • detection of easy (emtpy-block) and hard (encrypted block) to compress data
    • multi-threaded compression
    • sparse ranges
    • de-duplication