7. Smartcards & Related Application Infrastructures

Question 1

Smartcards

Answer 1

small computers with memory, operating system, software, processor, I/O & access control used, when security of data (e.g. for keys, signatures, physical access control, payment) needed in insecure environments (chip protected against manipulation)

Question 2

Why Smartcards?

Answer 2

protection needed against: unauthorised usage of service through forged user data, duplication of a user’s credentials, “cracking” of credentials, billing fraud

Question 3

Defintion: Subscriber Identity Module (SIM)

Answer 3

SIMs are smartcards!

• -represents contract between subscriber & network operator
• • authorizes a “phone” to use the network by linking it to a subscription
• -contain International Mobile Subscriber Identity (IMSI) for subscriber identification & the key K(i) provided by mobile operator

Question 4

Functionality of SIM (3)

Answer 4

• -SIM serves as “identity card” for GSM cellular phone subscribers
• -Allows for secure billing & roaming subscribers
• -Contains additional configuration data of GSM system

Question 5

SIM - Card Content

Answer 5

static data (IMSI, PIN, PUK, A3, A8, language preferred by subscriber) & dynamic data (cell & frequency information, dynamically generated keys, user data)

Question 6

Integration of SIM into Mobile Phones

Answer 6

ETSI GSM 11.11 specifies electrical & software interfaces between SIM and device –> “SIM Application Toolkit” (SAT) allows for implementing of additional applications on a SIM, e.g. mobile banking, location-based services

Question 7

WAP

Answer 7

WAP is a protocol family implementation of Client/Server applications on mobile devices

Question 8

WAP Identity Module (WIM)

Answer 8

WIM is implemented as an additional application on a -> should solve security problems raised
by WAP: Secure storage (for key/certificates), tamper resistance (of SIM based crypto algorithms), standardized interface (to security functions), RSA signatures are implemented on WIM

Question 9

USIM (def., features)

Answer 9

Universal SIM (for UMTS) - FEATURES; Support for multiple applications (SIM card & others), End-to-end security from USIM to application, Authentication of the network towards the USIM via cryptography (multilateral security possible), Downward compatible to SIM, Extended phone book on card (email addresses, numbers)

Question 10

definition: Secure Elements & UICC

Answer 10

SE are hardware tokens, that offer secure services (e.g. tamper-proof storage) -> UICC are one form factor of a SE, enabling secure mobile applications & services

Question 11

definition: ISIM

Answer 11

IP Multimedia Services Identity Module -> application running on a UICC smart card in a 3G mobile phone in IP Multimedia Subsystem (IMS) (can co-exist with SIM & USIM )

Question 12

ISIM - parameters for identifying & authenticating users

Answer 12

One private “IM Private Identity” (IMPI), One or more “IM Public Identities” (IMPU), Long-term secret used to authenticate & calculate cipher keys

Question 13

name SIM Applications (4)

Answer 13

Apple SIM, Google Fi Project, Embedded SIM (eSIM), CamWebSIM

Question 14

Apple SIM

Answer 14

SIM contains credentials for several networks – When travelling abroad, customer can use same SIM card for a chosen mobile data tariff from selected operators

Question 15

Google Fi Project

Answer 15

Connectivity through different operators (e.g. in cooperation with T-Mobile), High-speed data coverage in different countries with same conditions

Question 16

Embedded SIM (eSIM)

Answer 16

Embedded as a secure element in hardware - e.g. internet-enabled car (with navigation, congestion warning system, infotainment)

Question 17

CamWebSIM

Answer 17

a small quasi-HTTP server based on a GSM SIM card – by making SIM accessible over HTTP, the phone and the SIM become a personal security server in the Internet that is based on the GSM trust model – enables applications like authorizing a transaction or an access request (paying for Internet services via one’s GSM telephone account)