Question

Select the appropriate events in a simple challenge-response protocol from the following list and list them in the order of occurrence.      

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1. The host authenticates the user if the quantities match, or rejects the user otherwise.
2. The host generates a random number r, and returns r to the user.
3. The user responds the quantity f(r, h(P)) back to the host, where r is the nonce, P is the user’s password.
4. The host generates a random number r, and returns r and the specification of two functions, h() and f(), to the user.
5. The host compares the incoming h(P) to h(P(U)), where h(P(U))is the locally stored hash value of user U’s password.
6. The user responds the hash value h(r, P) back to the host, where r is the nonce, P is the user’s password.
7. The host compares the incoming h(r, P) to the calculated h(r, P(U)), where P(U) is the locally stored user U’s password.
8. The user transmits his or her identity, U, to the remote host.

1. The host compares the incoming f(r, h(P)) to the calculated f(r, h(P(U))), where h(P(U))is the locally stored hash value of user U’s password.

j. The user transmits his or her password, P, to the remote host.

k. The user transmits the hash value of his or her password, h(P), to the remote host.

Answer 1

Events in a simple challenge-response protocol are:

1.h.The user transmits his or her identity, U, to the remote host.

2. j. The user transmits his or her password, P, to the remote host.

3. b. The host generates a random number r, and returns r to the user.

4. c. The user responds the quantity f(r, h(P)) back to the host, where r is the nonce, P is the user’s password.

5.e. The host compares the incoming h(P) to h(P(U)), where h(P(U))is the locally stored hash value of user U’s password.

6.a. The host authenticates the user if the quantities match, or rejects the user otherwise.

These are the selected events form the list which has been arranged serial wise . The working of these events also happens serial wise.