USIM

From Wikipedia, the free encyclopedia

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 UMTS.

[edit] Equivalents on 2G

The equivalent of USIM on GSM networks is SIM.

The equivalent of USIM on CDMA networks is RUIM.

[edit] See also

• Universal Integrated Circuit Card (UICC)
• Subscriber Identity Module (SIM)
• IP Multimedia Identity Services Module (ISIM)

[edit] External links

• 3GPP TS 31.102 USIM standard