US Robotics USR2450 Informações Técnicas descarregar pdf (Página 20)

V 2.2 Copyright SystemExperts 2001,2002,2003

GSM Security

n International Mobile Equipment Identity (IMEI) for

each device to determine if device is allowed on the

network

n Shared secret: Stored in the Authentication Center

(AuC) and subscriber's SIM card

n Authentication: The AuC generates a random number sends it to

the mobile. Mobile uses A3 cipher and shared key to generate a

signed response sent back to the AuC

n Encryption: Use a key derived from A8 cipher using the same

pseudo random number+subscriber-key as above. Cipher key is

used with the TDMA frame number, in the A5 cipher to create a

value to XOR with data

n same process in IS-54/136 & PCS1900

V 2.2 Copyright SystemExperts 2001,2002,2003

Today’s Data Systems

n Primary mobile wireless data services are…

n Cellular Digital Packet Data (CDPD)

n iDEN packet service

n Circuit-switched data service for CDMA networks

(e.g., SprintPCS)

n Circuit-switched data services for GSM networks

n Modems and analog phones

n All of these services offer speeds in the 9.6 Kbps to

19.2 Kbps range

n How they deliver…

n Smart phones (phones with micro-browsers)

n Wireless modems (PC card or cable with phone)

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US Robotics USR2450 Informações Técnicas Página 20