Difference between pages "Microsoft PocketPC" and "SIM Cards"

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(Overview)
 
 
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[[Image:Simpic.jpg|thumb|A typical SIM card.]]
  
=Overview=
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== SIM-Subscriber Identity Module ==
A Pocket PC is commonly referred to as a handheld computer that runs a version of Microsoft’s proprietary mobile operating systems.
+
  
[[Image:Pocketpc.jpg|thumb|Acer Pocket PC]]
+
The UICC (Universal Integrated Circuit Card) is a smart card which contains account information and memory that is used to enable GSM cellular telephones.  One of the applications running on the smart card is the SIM, or Subscriber Identity Module. In common parlance the term "UICC" is not used an the phrase "SIM" is used to describe the smart card itself.
  
Microsoft Pocket PC, sometimes referred to as P/PC or PPC, is based upon the Windows CE framework.  Variants of this operating system include versions such as Pocket PC 2000, Pocket PC 2002, Windows Mobile 2003/2003 SE, and Windows Mobile 5.0. Variants also exist for [[SmartPhones]], such as Windows Mobile 2003 Smartphone edition.
+
Because the SIM is just one of several applications running on the smart card, a given card could, in theory, contain multiple SIMs. This would allow multiple phone numbers or accounts to be accessed by a single UICC. This is seldom seen, though there is at least one "12-in-1" SIM card being advertised at present.
  
One of the key benefits of Microsoft's Windows Mobile platform is file format compatibility with the desktop versions of the company's productivity softwareMobile versions of Microsoft software, such as Pocket Word, Pocket Excel, and Pocket PowerPoint, allow individuals to view and edit these files outside of the home and office.  
+
Early versions of the UICC used full-size smart cards (85mm x 54mm x 0.76mm)The card has since been shrunk to the standard size of 25mm x 15mm x 0.76mm.
  
Another benefit is integration with Microsoft's cross-platform solution, the .NET Framework.  The .NET Framework and its associated class libraries handle things such as memory management, file I/O, and many other functions.  The .NET Framework allows programmers to develop code in one of several .NET languages, such as C# and VB.NET.  Pocket PCs run a simplified version of the framework called the .NET Compact Framework.
 
  
In order to maintain synchronization and connectivity with desktop computers, Microsft developed the ActiveSync program.  The user merely has to connect the Pocket PC to the desktop computer in order to synchronize items such as appointments, contact lists, and even multimedia files.
+
Although UICC cards traditionally held just 16 to 64KB of memory, the recent trend has been to produce SIM cards with larger storage capacities, ranging from 512MB up to [http://www.m-systems.com/site/en-US/ M-Systems'] 1GB SIM Card slated for release in late 2006.
  
In 2001, [[PDAs]] running Palm OS variants held a market share of about 72%, while Pocket PC held a meager 15% of the market.  However, by the fourth quarter of 2004, Microsoft Pocket PC and Palm OS were practically tied with regards to market share -- Pocket PC-based devices had a market share of 40.2% while Palm OS claimed 40.7% of the market.  This upward trend clearly illustrates the growing popularity of Pocket PC-based devices, and thus the increased likelihood that one will encounter such a device in the field.
+
== ICCID ==
  
 +
Each SIM is internationally identified by its ICC-ID (Integrated Circuit Card ID). ICC-IDs are stored in the SIM card and can also be engraved or printed on the SIM card’s body during a process called personalization. The number is up to 18 digits long with an addition of a single “check digit” that is used for error detection.  This single digit allows us to detect an input error of digits, mistyped digits or a permutation of two successive digits.  This digit was calculated using the Luhn algorithm.
  
== History ==
+
A typical SIM (19 digits) example 89 91 10 1200 00 320451 0, provide several details as follows:
  
Windows CE, which serves as the framework for the Pocket PC operating systems, began its life in November of 1996. The NEC MobilePro 200 and the Casio A-10 were the first two PDA-type devices available with this early version of the operating system, which was dubbed Handheld PC 1.0.
+
*The first two digits (89 in the example) refers to the Telecom Id.
 +
*The next two digits (91 in the example) refers to the country code (91-India).
 +
*The next two digits (10 in the example) refers to the network code.
 +
*The next four digits (1200 in the example) refers to the month and year of manufacturing.
 +
*The next two digits (00 in the example) refers to the switch configuration code.
 +
*The next six digits (320451 in the example) refers to the SIM number.
 +
*The last digit which is separated from the rest is called the “check digit”.
  
Subsequently, Microsoft released iterations of its mobile operating systems with names such as Handheld PC 2.0 (1997), Palm-Size PC 2.0 (1998), Handheld PC Professional Edition (1998).
 
  
As development of Windows CE continued, manufacturers began to build more esoteric devices around it, such as internet TV set-top boxes and web-enabled telephones.
+
These digits can be further grouped for additional information:
 +
*The first 3 to 4 digits represents the Mobile Country Code (MCC) 
 +
**(Some cards only have 3 digits to represent the Telecom ID and country code.)
 +
*The next 2 digits represent the Mobile Network Code (MNC, AKA the mobile operator)
 +
*The next 12 digits is the number represent the Home Location Register
 +
*And mentioned above, the “check digit”
  
Pocket PC officially began its public life when it was previewed at the Consumer Electronics Show in 2000.  Codenamed "Rapier", the first version of the Pocket PC operating system was simply named Pocket PC.
+
== Location Area Identity==
  
=Pocket PC Variants=
+
Operation networks for cell phone devices are divided into area locations called Location Areas.  Each location is identified with its own unique identification number creating the LAI (Location Area Identity).  A phone will store this number on its SIM card so it knows what location it’s in and to be able to receive service.  If a phone were to change to a new Location Area, it stores the new LAI in the SIM card, adding to a list of all the previous LAIs it has been in.  This way if a phone is powered down, when it boots back up, it can search its list of LAIs it has stored until it finds the one its in and can start to receive service again.  This is much quicker than scanning the whole list of frequencies that a telephone can have access on. 
 +
This is a real plus for forensic investigators because when a SIM card is reviewed, they can get a general idea of where the SIM card has been geographically.  In turn this tells them where the phone has been and can then relate back to where the individual who owns the phone has been. 
  
==Pocket PC 2000==
+
== SIM Security ==
  
Pocket PC 2000, based on Micrsoft's Windows CE 3.0 platform, was a first step towards the familiar appearance and functionality that is offered by Windows Mobile 5.0.  Devices running Pocket PC 2000 ranged from the Askey PC010, which had a 16-color grayscale screen with no expansion slots, to the Casio EM-500, which had a 64k color screen and provisions for upgraded pheripherals such as cameras.  Pocket PC 2000 launched with versions of Pocket Word, Pocket Excel, and Microsoft Reader bundled.  ActiveSync 3.1, which provided an easier way to install applications onto the Pocket PC, was required to synchronize with host desktop machines.
+
Information inside the UICC can be protected with a PIN and a PUK.
  
==Pocket PC 2002==
+
A PIN locks the SIM card until correct code is entered. Each phone network sets the PIN of SIM to a standard default number (this can be changed via handset). If PIN protection is enabled, the PIN will need to be entered each time phone is switched on. If the PIN is entered incorrectly 3 times in a row, the SIM card will be blocked requiring a PUK from the network/service provider.
Codenamed "Merlin," Pocket PC 2002 was Microsoft's Windows CE 3.0-based upgrade to Pocket PC 200. Pocket PC 2002 offered many improvements over the previous operating system, including a Terminal Service Client, a new mail Inbox, Windows Media Player 8.0, improved versions of Pocket Word and MS Reader, and many other features.
+
  
There were three service packs (EUUU1/2/3) released which addressed bugs and other issues in the original release.
+
A PUK is needed if the PIN is entered incorrectly 3 times and the SIM is blocked (phone is unable to make and receive calls/texts). The PUK can be received from the network provider, or possibly the GSM cell phone manual. '''Caution:''' if PUK is entered 10 times incorrectly, the SIM card is permanently disabled and must be exchanged.
  
==Windows Mobile 2003 & 2003 Second Edition==
+
== SIM Forensics ==
Windows Mobile 2003, codenamed "Ozone", was officially released in June of 2003.  The operating system is based on Microsoft's Windows CE 4.2, which claimed to provide a more responsive system when compared with devices running Windows CE 3.0.  This version of the operating system added many useful features, including a picture viewer, built-in Bluetooth and WiFi support, Windows Media Player 9.0, as well as a host of Personal Information Management application improvements.  This version of Windows Mobile required ActiveSync 3.7 to communicate with a host computer.
+
  
Windows Mobile Second Edition, released in 2004, added support for 640x480 VGA resolution, portrait and landscape display modes, DPI settings, and many other improvements.
+
The data that a SIM card can provide the forensics examiner can be invaluable to an investigation. Acquiring a SIM card allows a large amount of information that the suspect has dealt with over the phone to be investigated.
  
==Windows Mobile 5.0==
+
In general, some of this data can help an investigator determine:
Windows Mobile 5.0, based off of Windows CE 5.0, was released on May 10, 2005.  Windows Mobile 5.0 brought many changes to the Pocket PC landscape.  For one, with this release, the phone and PDA versions of the OS have merged into one encompassing OS, instead of two separate versions of the same one.  Additionally, while past versions of Pocket PC software utilized the RAM of a PDA for program and data storage, Windows Mobile 5.0 uses a PDA's hardware more like a traditional computer.  The operating system and user data is stored in the more persistent ROM of the device, and RAM is used in a way more similar to that of a desktop PC.  This has implications for forensics, as data stored on these devices is now less volatile.
+
* Phone numbers of calls made/received
 +
* Contacts
 +
* [[SMS]] details (time/date, recipient, etc.)
 +
* SMS text (the message itself)
  
=Pocket PC Devices=
+
There are many software solutions that can help the examiner to acquire the information from the SIM card. Several products include 3GForensics SIMIS [http://www.3gforensics.co.uk/products.htm], Inside Out's [http://simcon.no/ SIMCon], or SIM Content Controller, and Paraben Forensics' [http://www.paraben-forensics.com/catalog/product_info.php?products_id=289 SIM Card Seizure].
  
[[Image:Treo.jpg|thumb|Treo 700w]]
+
The SIM file system is hierarchical in nature consisting of 3 parts:
 +
*Master File (MF) - root of the file system that contains
 +
DF’s and EF’s
 +
*Dedicated File (DF)
 +
*Elementary Files (EF)
  
In recent years, a number of manufacturers have elected to produce Pocket PC devices.  Some of these makers include companies such as:
 
  
*  Acer
+
=== Data Acquisition ===
*  Asus
+
*  Audiovox
+
*  Dell
+
*  HP
+
*  Mitac
+
*  Motorola
+
*  Samsung
+
*  Siemens
+
*  Symbol
+
*  Treo
+
  
Because different manufacturers are targeted at different segments of the market, such as business and consumers, the features and functionality of these devices sometimes differ greatly.  For example, some devices have built-in capability for taking images and videos, while other devices have tools such as biometric fingerprint readers and barcode scanners.
+
These software titles can extract such technical data from the SIM card as:
  
=References=
+
* '''International Mobile Subscriber Identity (IMSI)''': A unique identifying number that identifies the phone/subscription to the [[GSM]] network
 +
* '''Mobile Country Code (MCC)''': A three-digit code that represents the SIM card's country of origin
 +
* '''Mobile Network Code (MNC)''': A two-digit code that represents the SIM card's home network
 +
* '''Mobile Subscriber Identification Number (MSIN)''': A unique ten-digit identifying number that identifies the specific subscriber to the GSM network
 +
* '''Mobile Subscriber International ISDN Number (MSISDN)''': A number that identifies the phone number used by the headset
 +
* '''Abbreviated Dialing Numbers (ADN)''': Telephone numbers stored in sims memory
 +
* '''Last Dialed Numbers (LDN)'''
 +
* '''Short Message Service (SMS)''': Text Messages
 +
* '''Public Land Mobile Network (PLMN) selector'''
 +
* '''Forbidden PLMNs'''
 +
* '''Location Information (LOCI)'''
 +
* '''General Packet Radio Service (GPRS) location'''
 +
* '''Integrated Circuit Card Identifier (ICCID)'''
 +
* '''Service Provider Name (SPN)'''
 +
* '''Phase Identification'''
 +
* '''SIM Service Table (SST)'''
 +
* '''Language Preference (LP)'''
 +
* '''Card Holder Verification (CHV1) and (CHV2)'''
 +
* '''Broadcast Control Channels (BCCH)'''
 +
* '''Ciphering Key (Kc)'''
 +
* '''Ciphering Key Sequence Number'''
 +
* '''Emergency Call Code'''
 +
* '''Fixed Dialing Numbers (FDN)'''
 +
* '''Forbidden PLMNs'''
 +
* '''Local Area Identitity (LAI)'''
 +
* '''Own Dialing Number'''
 +
* '''Temporary Mobile Subscriber Identity (TMSI)'''
 +
* '''Routing Area Identifier (RIA) netowrk code'''
 +
* '''Service Dialing Numbers (SDNs)'''
 +
* '''Service Provider Name'''
 +
* '''Depersonalizatoin Keys'''
  
[http://www.hpcfactor.com/support/windowsce/ The History of Microsoft Windows CE]
+
This information can be used to contact the service provider to obtain even more information than is stored on the SIM card.
  
[http://palmtops.about.com/cs/pdafacts/a/Palm_Pocket_PC.htm Palm vs. Pocket PC-The Great Debate]
+
== USIM-Universal Subscriber Identity Module ==
  
[http://www.windowsfordevices.com/news/NS8063885791.html Gartner: Windows CE ties Palm]
+
A Universal Subscriber Identity Module is an application for UMTS mobile telephony running on a UICC smart card which is inserted in a 3G mobile phone. There is a common misconception to call the UICC card itself a USIM, but the USIM is merely a logical entity on the physical card.
  
[http://en.wikipedia.org/wiki/Pocket_PC Wikipedia: Pocket PC]
+
It stores user subscriber information, authentication information and provides storage space for text messages and phone book contacts. The phone book on a UICC has been greatly enhanced.
  
[http://www.pocketpcfaq.com PocketPC FAQ]
+
For authentication purposes, the USIM stores a long-term preshared secret key K, which is shared with the Authentication Center (AuC) in the network. The USIM also verifies a sequence number that must be within a range using a window mechanism to avoid replay attacks, and is in charge of generating the session keys CK and IK to be used in the confidentiality and integrity algorithms of the KASUMI block cipher in Universal Mobile Telecommunications System (UMTS).
 +
 
 +
In Mobile Financial Services, USIM seems to be a mandetory Security Element for user authentication, authorization and stored credentials. With the integration of NFC Handset and USIM, users will be able to make proximity payments where the NFS handset enables contactless payment and USIM enables independent security element.
 +
This is the evolution of the SIM for 3G devices. It can allow for multiple phone numbers to be assigned to the USIM, thus giving more than one phone number to a device.
 +
 
 +
== Service Provider Data ==
 +
 
 +
Some additional information the service provider might store:
 +
 
 +
* A customer database
 +
* [[Call Detail Record]]s (CDR)
 +
* [[Home Location Register]] (HLR)
 +
 
 +
 
 +
== Service Providers that use SIM Cards in the United States ==
 +
* T-Mobile
 +
* Cingular/AT&T
 +
 
 +
== Sim Card Text Encoding ==
 +
 
 +
Originally the middle-European [[GSM]] network used only a 7-bit code derived from the basic [[ASCII]] code. However as GSM spread worldwide it was concluded that more characters, such as the major characters of all living languages, should be able to be represented on GSM phones. Thus, there was a movement towards a 16-bit code known as [[UCS-2]] which is now the standard in GSM text encoding. This change in encoding can make it more difficult to accurately obtain data form [[SIM cards]] of the older generation which use the 7-bit encoding. This encoding is used to compress the hexadecimal size of certain elements of the SIMs data, particularly in [[SMS]] and [[Abbreviated Dialing Numbers]].
 +
 
 +
== Authentication Key (Ki) ==
 +
The authentication key or Ki is a 128 bit key used in the authentication and cipher key generation process. In a nutshell, the key is used to authenticate the SIM on the GSM network. Each SIM contains this key which is assigned to it by the operator during the personalization process. The SIM card is specially designed so the Ki can't be compromised using a smart-card interface. However, flaws in the GSM cryptography have been discovered that do allow the extraction of the Ki from the SIM card, and essentially SIM card duplication.
 +
 
 +
== See also ==
 +
 
 +
* [[SIM Card Forensics]]
 +
 
 +
== References ==
 +
 
 +
* [http://www.simcon.no/ SIMCon]
 +
* [http://www.sectorforensics.co.uk/sim-examination.shtml Sector Forensics]
 +
* [http://www.utica.edu/academic/institutes/ecii/ijde/articles.cfm?action=issue&id=5  IJDE Spring 2003 Volume 2, Issue 1 ]: [http://www.utica.edu/academic/institutes/ecii/publications/articles/A0658858-BFF6-C537-7CF86A78D6DE746D.pdf Forensics and the GSM Mobile Telephone System] (PDF)
 +
* http://en.wikipedia.org/wiki/Subscriber_Identity_Module

Revision as of 07:56, 29 September 2008

A typical SIM card.

SIM-Subscriber Identity Module

The UICC (Universal Integrated Circuit Card) is a smart card which contains account information and memory that is used to enable GSM cellular telephones. One of the applications running on the smart card is the SIM, or Subscriber Identity Module. In common parlance the term "UICC" is not used an the phrase "SIM" is used to describe the smart card itself.

Because the SIM is just one of several applications running on the smart card, a given card could, in theory, contain multiple SIMs. This would allow multiple phone numbers or accounts to be accessed by a single UICC. This is seldom seen, though there is at least one "12-in-1" SIM card being advertised at present.

Early versions of the UICC used full-size smart cards (85mm x 54mm x 0.76mm). The card has since been shrunk to the standard size of 25mm x 15mm x 0.76mm.


Although UICC cards traditionally held just 16 to 64KB of memory, the recent trend has been to produce SIM cards with larger storage capacities, ranging from 512MB up to M-Systems' 1GB SIM Card slated for release in late 2006.

ICCID

Each SIM is internationally identified by its ICC-ID (Integrated Circuit Card ID). ICC-IDs are stored in the SIM card and can also be engraved or printed on the SIM card’s body during a process called personalization. The number is up to 18 digits long with an addition of a single “check digit” that is used for error detection. This single digit allows us to detect an input error of digits, mistyped digits or a permutation of two successive digits. This digit was calculated using the Luhn algorithm.

A typical SIM (19 digits) example 89 91 10 1200 00 320451 0, provide several details as follows:

  • The first two digits (89 in the example) refers to the Telecom Id.
  • The next two digits (91 in the example) refers to the country code (91-India).
  • The next two digits (10 in the example) refers to the network code.
  • The next four digits (1200 in the example) refers to the month and year of manufacturing.
  • The next two digits (00 in the example) refers to the switch configuration code.
  • The next six digits (320451 in the example) refers to the SIM number.
  • The last digit which is separated from the rest is called the “check digit”.


These digits can be further grouped for additional information:

  • The first 3 to 4 digits represents the Mobile Country Code (MCC)
    • (Some cards only have 3 digits to represent the Telecom ID and country code.)
  • The next 2 digits represent the Mobile Network Code (MNC, AKA the mobile operator)
  • The next 12 digits is the number represent the Home Location Register
  • And mentioned above, the “check digit”

Location Area Identity

Operation networks for cell phone devices are divided into area locations called Location Areas. Each location is identified with its own unique identification number creating the LAI (Location Area Identity). A phone will store this number on its SIM card so it knows what location it’s in and to be able to receive service. If a phone were to change to a new Location Area, it stores the new LAI in the SIM card, adding to a list of all the previous LAIs it has been in. This way if a phone is powered down, when it boots back up, it can search its list of LAIs it has stored until it finds the one its in and can start to receive service again. This is much quicker than scanning the whole list of frequencies that a telephone can have access on. This is a real plus for forensic investigators because when a SIM card is reviewed, they can get a general idea of where the SIM card has been geographically. In turn this tells them where the phone has been and can then relate back to where the individual who owns the phone has been.

SIM Security

Information inside the UICC can be protected with a PIN and a PUK.

A PIN locks the SIM card until correct code is entered. Each phone network sets the PIN of SIM to a standard default number (this can be changed via handset). If PIN protection is enabled, the PIN will need to be entered each time phone is switched on. If the PIN is entered incorrectly 3 times in a row, the SIM card will be blocked requiring a PUK from the network/service provider.

A PUK is needed if the PIN is entered incorrectly 3 times and the SIM is blocked (phone is unable to make and receive calls/texts). The PUK can be received from the network provider, or possibly the GSM cell phone manual. Caution: if PUK is entered 10 times incorrectly, the SIM card is permanently disabled and must be exchanged.

SIM Forensics

The data that a SIM card can provide the forensics examiner can be invaluable to an investigation. Acquiring a SIM card allows a large amount of information that the suspect has dealt with over the phone to be investigated.

In general, some of this data can help an investigator determine:

  • Phone numbers of calls made/received
  • Contacts
  • SMS details (time/date, recipient, etc.)
  • SMS text (the message itself)

There are many software solutions that can help the examiner to acquire the information from the SIM card. Several products include 3GForensics SIMIS [1], Inside Out's SIMCon, or SIM Content Controller, and Paraben Forensics' SIM Card Seizure.

The SIM file system is hierarchical in nature consisting of 3 parts:

  • Master File (MF) - root of the file system that contains

DF’s and EF’s

  • Dedicated File (DF)
  • Elementary Files (EF)


Data Acquisition

These software titles can extract such technical data from the SIM card as:

  • International Mobile Subscriber Identity (IMSI): A unique identifying number that identifies the phone/subscription to the GSM network
  • Mobile Country Code (MCC): A three-digit code that represents the SIM card's country of origin
  • Mobile Network Code (MNC): A two-digit code that represents the SIM card's home network
  • Mobile Subscriber Identification Number (MSIN): A unique ten-digit identifying number that identifies the specific subscriber to the GSM network
  • Mobile Subscriber International ISDN Number (MSISDN): A number that identifies the phone number used by the headset
  • Abbreviated Dialing Numbers (ADN): Telephone numbers stored in sims memory
  • Last Dialed Numbers (LDN)
  • Short Message Service (SMS): Text Messages
  • Public Land Mobile Network (PLMN) selector
  • Forbidden PLMNs
  • Location Information (LOCI)
  • General Packet Radio Service (GPRS) location
  • Integrated Circuit Card Identifier (ICCID)
  • Service Provider Name (SPN)
  • Phase Identification
  • SIM Service Table (SST)
  • Language Preference (LP)
  • Card Holder Verification (CHV1) and (CHV2)
  • Broadcast Control Channels (BCCH)
  • Ciphering Key (Kc)
  • Ciphering Key Sequence Number
  • Emergency Call Code
  • Fixed Dialing Numbers (FDN)
  • Forbidden PLMNs
  • Local Area Identitity (LAI)
  • Own Dialing Number
  • Temporary Mobile Subscriber Identity (TMSI)
  • Routing Area Identifier (RIA) netowrk code
  • Service Dialing Numbers (SDNs)
  • Service Provider Name
  • Depersonalizatoin Keys

This information can be used to contact the service provider to obtain even more information than is stored on the SIM card.

USIM-Universal Subscriber Identity Module

A Universal Subscriber Identity Module is an application for UMTS mobile telephony running on a UICC smart card which is inserted in a 3G mobile phone. There is a common misconception to call the UICC card itself a USIM, but the USIM is merely a logical entity on the physical card.

It stores user subscriber information, authentication information and provides storage space for text messages and phone book contacts. The phone book on a UICC has been greatly enhanced.

For authentication purposes, the USIM stores a long-term preshared secret key K, which is shared with the Authentication Center (AuC) in the network. The USIM also verifies a sequence number that must be within a range using a window mechanism to avoid replay attacks, and is in charge of generating the session keys CK and IK to be used in the confidentiality and integrity algorithms of the KASUMI block cipher in Universal Mobile Telecommunications System (UMTS).

In Mobile Financial Services, USIM seems to be a mandetory Security Element for user authentication, authorization and stored credentials. With the integration of NFC Handset and USIM, users will be able to make proximity payments where the NFS handset enables contactless payment and USIM enables independent security element. This is the evolution of the SIM for 3G devices. It can allow for multiple phone numbers to be assigned to the USIM, thus giving more than one phone number to a device.

Service Provider Data

Some additional information the service provider might store:


Service Providers that use SIM Cards in the United States

  • T-Mobile
  • Cingular/AT&T

Sim Card Text Encoding

Originally the middle-European GSM network used only a 7-bit code derived from the basic ASCII code. However as GSM spread worldwide it was concluded that more characters, such as the major characters of all living languages, should be able to be represented on GSM phones. Thus, there was a movement towards a 16-bit code known as UCS-2 which is now the standard in GSM text encoding. This change in encoding can make it more difficult to accurately obtain data form SIM cards of the older generation which use the 7-bit encoding. This encoding is used to compress the hexadecimal size of certain elements of the SIMs data, particularly in SMS and Abbreviated Dialing Numbers.

Authentication Key (Ki)

The authentication key or Ki is a 128 bit key used in the authentication and cipher key generation process. In a nutshell, the key is used to authenticate the SIM on the GSM network. Each SIM contains this key which is assigned to it by the operator during the personalization process. The SIM card is specially designed so the Ki can't be compromised using a smart-card interface. However, flaws in the GSM cryptography have been discovered that do allow the extraction of the Ki from the SIM card, and essentially SIM card duplication.

See also

References