Question

In this task, you need to critically analyze the below protocols and clearly explain which protocol or protocols would be secured and why.

The prospective security protocols are as follows:

Alice --> msg1 --> Bob
Alice <-- msg2 <-- Bob
Alice --> Rb --> Bob

a) In protocol-1, Message 1: E(“Alice”, K, RA, KAB), Message 2: RA, E(RB, KAB)

b) In protocol-2, Message 1: “Alice”, E(K, RA, KAB), Message 2: RA, E(RB, K)

c) In protocol-3, Message 1: “Alice”, E(K, RA, KAB), Message 2: RA, E(RB, KAB)

d) In protocol-4, Message 1: “Alice”, RA, Message 2: E(K, RA, RB, KAB)

Note:

K : Session key

RA : Nonce generated by Alice

RB : Nonce generated by Bob

KAB : Shared secret key between Alice and Bob

E(“Message”, KAB) : Symmetric Encryption Function that encrypts “Message” using KAB

Answer 1

Protocol 2 is used between alice and bob as, protocol 2 is a practical, mutual authentication, and the session key K is secure.

As the protocol uses In protocol-2, Message 1: “Alice”, E(K, RA, KAB), Message 2: RA, E(RB, K), which shows mutual authentication between sender and receiver, so protocol 2 is secured and used.

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