Difference between pages "Cell phones" and "Gzip"

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(File format)
 
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'''Cell phones''' or '''mobile phones''' are an important target for [[forensic investigator]]s.
+
{{expand}}
  
== Technologies ==
+
== File format ==
+
The gzip file (.gz) format consists of:
* [[CDMA]]
+
* a file header
* [[TDMA]]
+
* optional headers
* [[GSM]]
+
** extra fields
* [[iDEN]]
+
** original file name
* [[EDGE]]
+
** comment
* [[GPRS]]
+
** header checksum
* [[UMTS]]
+
* a body, containing a DEFLATE-compressed payload
 +
* a file footer
  
== Hardware ==
+
The gzip format uses little-endian.
  
* [[RIM BlackBerry]]
+
{| class="wikitable"
* [[T-Mobile Sidekick  ]]
+
! align="left"| Offset
* [[SIM Cards]]
+
! Characteristics
 +
! Description
 +
|-
 +
| Byte order
 +
| little-endian
 +
|-
 +
| Date and time values
 +
| Filetime in UTC
 +
|-
 +
| Character string
 +
| ISO 8859-1 (LATIN-1)
 +
|}
  
== Operating Systems ==
+
=== File header ===
 +
The file header is 10 bytes in size and contains:
 +
{| class="wikitable"
 +
! align="left"| Offset
 +
! Size
 +
! Value
 +
! Description
 +
|-
 +
| 0
 +
| 2
 +
| 0x1f 0x8b
 +
| Signature (or identification byte 1 and 2)
 +
|-
 +
| 2
 +
| 1
 +
|
 +
| Compression Method
 +
|-
 +
| 3
 +
| 1
 +
|
 +
| Flags
 +
|-
 +
| 4
 +
| 4
 +
|
 +
| Last modification time <br> Contains a POSIX timestamp.
 +
|-
 +
| 8
 +
| 1
 +
|
 +
| Extra flags
 +
|-
 +
| 9
 +
| 1
 +
|
 +
| Operating system <br> Value that indicates on which operating system the gzip file was created.
 +
|}
  
* [[Microsoft PocketPC]]
+
==== Compression method ====
* [[Microsoft Windows Mobile]]
+
* [[Palm]]
+
* [[RIM BlackBerry]]
+
* [[Symbian]]
+
* [[Linux]]
+
  
== Forensics ==
+
{| class="wikitable"
 +
! align="left"| Value
 +
! Identifier
 +
! Description
 +
|-
 +
| 0 - 7
 +
|
 +
| Reserved
 +
|-
 +
| 8
 +
| "deflate"
 +
| zlib compressed data
 +
|}
  
'''Procedures'''
+
==== Flags ====
  
* [[Cell Phone Forensics]]
+
{| class="wikitable"
* [[SIM Card Forensics]]
+
! align="left"| Value
* [[External Memory Card Forensics]]
+
! Identifier
* [[Blackberry Forensics]]
+
! Description
 +
|-
 +
| 0x01
 +
| FTEXT
 +
| If set the uncompressed data needs to be treated as text instead of binary data. <br> This flag hints end-of-line conversion for cross-platform text files but does not enforce it.
 +
|-
 +
| 0x02
 +
| FHCRC
 +
| The file contains a header checksum (CRC-16)
 +
|-
 +
| 0x04
 +
| FEXTRA
 +
| The file contains extra fields
 +
|-
 +
| 0x08
 +
| FNAME
 +
| The file contains an original file name string
 +
|-
 +
| 0x10
 +
| FCOMMENT
 +
| The file contains comment
 +
|-
 +
| 0x20
 +
|
 +
| Reserved
 +
|-
 +
| 0x40
 +
|
 +
| Reserved
 +
|-
 +
| 0x80
 +
|
 +
| Reserved
 +
|}
  
== Tools ==
+
<b>Note:</b> The FHCRC bit was never set by versions of gzip up to 1.2.4, even though it was documented with a different meaning in gzip 1.2.4.
  
'''Flashers'''
+
==== Extra flags ====
* [[UFS Tornado]]
+
If compression method is 8 the following extra flags can be defined:
 +
{| class="wikitable"
 +
! align="left"| Value
 +
! Identifier
 +
! Description
 +
|-
 +
| 0x02
 +
|
 +
| compressor used maximum compression, slowest algorithm
 +
|-
 +
| 0x04
 +
|
 +
| compressor used fastest algorithm
 +
|}
  
'''Hardware'''
+
==== Operating System ====
* [[Azimuth RadioProof™ Enclosures]]
+
{| class="wikitable"
* [[Cellebrite UFED]]
+
! align="left"| Value
* [[LogiCube CellDEK]]
+
! Identifier
* [[LogiCube CellDEK TEK]]
+
! Description
* [http://www.msab.com/xry/field-version| Micro Systemation Field Version]
+
|-
* [[Network Security Solutions Secure Tents]]
+
| 0
* [[Network Security Solutions Seizure Bags for Cell Phones/PDAs/Laptops]]
+
|
* [[Paraben CSI Stick]]
+
| FAT filesystem (MS-DOS, OS/2, NT/Win32)
* [[Paraben Device Seizure Toolbox]]
+
|-
* [[Paraben Handheld First Responder Kit]]
+
| 1
* [[Paraben StrongHold Bag]]
+
|
* [[Radio Frequency (RF) Jammers]]
+
| Amiga
* [[Radio Tactics Acesso]]
+
|-
* [[Radio Tactics Apollo]]
+
| 2
* [[Radio Tactics Athena]]
+
|
* [[SIM Card Readers]]
+
| VMS (or OpenVMS)
 +
|-
 +
| 3
 +
|
 +
| Unix
 +
|-
 +
| 4
 +
|
 +
| VM/CMS
 +
|-
 +
| 5
 +
|
 +
| Atari TOS
 +
|-
 +
| 6
 +
|
 +
| HPFS filesystem (OS/2, NT)
 +
|-
 +
| 7
 +
|
 +
| Macintosh
 +
|-
 +
| 8
 +
|
 +
| Z-System
 +
|-
 +
| 9
 +
|
 +
| CP/M
 +
|-
 +
| 10
 +
|
 +
| TOPS-20
 +
|-
 +
| 11
 +
|
 +
| NTFS filesystem (NT)
 +
|-
 +
| 12
 +
|
 +
| QDOS
 +
|-
 +
| 13
 +
|
 +
| Acorn RISCOS
 +
|-
 +
| 255
 +
|
 +
| unknown
 +
|}
  
'''Software'''
+
=== Optional headers ===
* [[BitPIM]]
+
==== Extra fields ====
* [[BK Forensics Cell Phone Analyzer]]
+
<b>TODO: add description</b>
* [[FloAt's Mobile Agent]]
+
* [[ForensicMobile]]
+
* [[ForensicSIM]]
+
* [[Guidance Software Neutrino]]
+
* [[iDEN Companion Pro]]
+
* [[iDEN Media Downloader]]
+
* [[iDEN Phonebook Manager]]
+
* [[.XRY |MicroSystemation .XRY]]
+
* [[MOBILedit!]]
+
* [[Oxygen Forensic Suite 2010]]
+
* [[Paraben Device Seizure]]
+
* [[Paraben SIM Seizure]]
+
* [[Pandora's Box]]
+
* [[Quantaq USIMdetective]]
+
* [[Quantaq USIMcommander]]
+
* [[Quantaq USIMdetective]]
+
* [[Quantaq USIMexplorer]]
+
* [[Quantaq USIMprofiler]]
+
* [[Quantaq USIMregistrar]]
+
* [[SIMiFOR]]
+
* [[Susteen Secure View]]
+
* [[TULP2G]]
+
* [[WOLF]]
+
  
==See Also==
+
The extra field are variable of size and contains:
[[Cell phone forensics bibliography]]
+
{| class="wikitable"
 +
! align="left"| Offset
 +
! Size
 +
! Value
 +
! Description
 +
|-
 +
| 0
 +
| 2
 +
|
 +
| Extra field data size <br> Value in bytes.
 +
|-
 +
| 2
 +
| ...
 +
|
 +
| Extra field data
 +
|}
 +
 
 +
==== Original file name ====
 +
This is the original name of the file being compressed, with any directory components removed, and, if the file being compressed is on a file system with case insensitive names, forced to lower case.
 +
 
 +
Contains an ISO 8859-1 (LATIN-1) string with end-of-string character.
 +
 
 +
==== Comment ====
 +
Contains an ISO 8859-1 (LATIN-1) string with end-of-string character. Line breaks should be denoted by a single line feed character.
 +
 
 +
==== Header checksum ====
 +
The header checksum contain a CRC-16 that consists of the two least significant bytes of the CRC-32 for all bytes of the gzip header up to and not including the CRC-16.
 +
 
 +
=== File footer ===
 +
The file footer is 8 bytes in size and contains:
 +
{| class="wikitable"
 +
! align="left"| Offset
 +
! Size
 +
! Value
 +
! Description
 +
|-
 +
| 0
 +
| 4
 +
|
 +
| Checksum (CRC-32)
 +
|-
 +
| 4
 +
| 4
 +
|
 +
| Uncompressed data size <br> Value in bytes.
 +
|}
 +
 
 +
== See Also ==
 +
* [[bz2 file]]
 +
 
 +
== External Links ==
 +
 
 +
* [http://www.gzip.org/format.txt The gzip file format], by the [http://www.gzip.org/ gzip project]
 +
* [http://www.gzip.org/algorithm.txt The gzip compression algorithm], by the [http://www.gzip.org/ gzip project]
 +
* [http://tools.ietf.org/html/rfc1952 RFC1952: GZIP file format specification version 4.3], by [[IETF]]
 +
* [http://en.wikipedia.org/wiki/Gzip Wikipedia: gzip]
 +
 
 +
[[Category:File Formats]]

Revision as of 23:22, 28 November 2013

Information icon.png

Please help to improve this article by expanding it.
Further information might be found on the discussion page.

File format

The gzip file (.gz) format consists of:

  • a file header
  • optional headers
    • extra fields
    • original file name
    • comment
    • header checksum
  • a body, containing a DEFLATE-compressed payload
  • a file footer

The gzip format uses little-endian.

Offset Characteristics Description
Byte order little-endian
Date and time values Filetime in UTC
Character string ISO 8859-1 (LATIN-1)

File header

The file header is 10 bytes in size and contains:

Offset Size Value Description
0 2 0x1f 0x8b Signature (or identification byte 1 and 2)
2 1 Compression Method
3 1 Flags
4 4 Last modification time
Contains a POSIX timestamp.
8 1 Extra flags
9 1 Operating system
Value that indicates on which operating system the gzip file was created.

Compression method

Value Identifier Description
0 - 7 Reserved
8 "deflate" zlib compressed data

Flags

Value Identifier Description
0x01 FTEXT If set the uncompressed data needs to be treated as text instead of binary data.
This flag hints end-of-line conversion for cross-platform text files but does not enforce it.
0x02 FHCRC The file contains a header checksum (CRC-16)
0x04 FEXTRA The file contains extra fields
0x08 FNAME The file contains an original file name string
0x10 FCOMMENT The file contains comment
0x20 Reserved
0x40 Reserved
0x80 Reserved

Note: The FHCRC bit was never set by versions of gzip up to 1.2.4, even though it was documented with a different meaning in gzip 1.2.4.

Extra flags

If compression method is 8 the following extra flags can be defined:

Value Identifier Description
0x02 compressor used maximum compression, slowest algorithm
0x04 compressor used fastest algorithm

Operating System

Value Identifier Description
0 FAT filesystem (MS-DOS, OS/2, NT/Win32)
1 Amiga
2 VMS (or OpenVMS)
3 Unix
4 VM/CMS
5 Atari TOS
6 HPFS filesystem (OS/2, NT)
7 Macintosh
8 Z-System
9 CP/M
10 TOPS-20
11 NTFS filesystem (NT)
12 QDOS
13 Acorn RISCOS
255 unknown

Optional headers

Extra fields

TODO: add description

The extra field are variable of size and contains:

Offset Size Value Description
0 2 Extra field data size
Value in bytes.
2 ... Extra field data

Original file name

This is the original name of the file being compressed, with any directory components removed, and, if the file being compressed is on a file system with case insensitive names, forced to lower case.

Contains an ISO 8859-1 (LATIN-1) string with end-of-string character.

Comment

Contains an ISO 8859-1 (LATIN-1) string with end-of-string character. Line breaks should be denoted by a single line feed character.

Header checksum

The header checksum contain a CRC-16 that consists of the two least significant bytes of the CRC-32 for all bytes of the gzip header up to and not including the CRC-16.

File footer

The file footer is 8 bytes in size and contains:

Offset Size Value Description
0 4 Checksum (CRC-32)
4 4 Uncompressed data size
Value in bytes.

See Also

External Links