3.20 pts) Use a block cypher with the following mapping table. Each block contai

Question

3.20 pts) Use a block cypher with the following mapping table. Each block contains 3 bits. (e) Assame we use simple text substitution. The plaintext is 010101011, what will be the ciphertext? (b) Now assuming we use the Cipher Blocking Chaining (CBC). Suppose the initiation vector C(0) is 010. What will be the ciphertext? Note that in CBC, a block ciphertext is fed back to be XORed with th input. input output input output 000 110 001 111 010 101 011 100 100 011 101 010 110 000 111 001 4. (10 pts) What are the roles of the EIR, HLR, and VLR in GSM?

Explanation / Answer

4)Answer:

EIR:

EIR stands for Equipment Identity Register (EIR).It is a database that contains a list of all valid mobile equipment on the network, where its International Mobile Equipment Identity (IMEI) identifies each MS. An IMEI is marked as invalid if it has been reported stolen or is not type approved.

->In the gsm system the eir is the equipment identity register which is a database that contains the mobiles id along with the sim installed in it .

it is used for theft prevebntion by baring the mobile from accessing the mobile network

HLR:

HLR stands for Home Location Register (HLR) .The HLR is a database used for storage and management of subscriptions. The HLR is considered the most important database, as it stores permanent data about subscribers, including a subscriber's service profile, location information, and activity status. When an individual buys a subscription in the form of SIM, then all the information about this subscription is registered in the HLR of that operator.

HLR is basically Home location Register is a database used for permanent storage of customer information.

VLR:

The VLR is a database that contains temporary information about subscribers that is needed by the MSC in order to service visiting subscribers. The VLR is always integrated with the MSC. When a mobile station roams into a new MSC area, the VLR connected to that MSC will request data about the mobile station from the HLR. Later, if the mobile station makes a call, the VLR will have the information needed for call setup without having to interrogate the HLR each time.

VLR is basically Visitor Location Register is similar to HLR but it store data of Subscriber migrate from one location to another, i.e location of subscriber in Roming.

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