# NPTEL Blockchain and its Applications Week 2 Assignment Answers 2024

## NPTEL Blockchain and its Applications Week 2 Assignment Answers 2024

1. Alice employs the RSA cryptosystem with the prime numbers p = 7 and q = 17 to
derive her public and private keys. Given that Alice’s public key is 11, her
corresponding private key is_______________

`Answer :- For Answer Click Here`

2.

Bob wishes to send a lengthy message to Alice with the requirement that Alice can
verify its origin and Bob cannot later disown the message. They also want to ensure
the confidentiality of the message. Alice and Bob decide to employ public key
cryptography and cryptographic hashing techniques. Let the key pairs for Alice and
Bob be (Pub A, Pri A) and (Pub B, Pri B) respectively, and let E, D, and H denote the
encryption, decryption, and hash functions respectively. M represents the message,
and H(M) is its digest. Which of the following outlines the correct sequence of steps
for Alice to send the digitally signed message?
i. At Bob: M° = E(M, Kpuba)
II. At Alice: M = E(M, KpriA)
Ill. Bob sends the message Mi to Alice
iv. The signature along with the message is sent to Alice (M, M’)
v. Bob: M’ = E(M, Крв)
vi. Signing the message with his private key: S = E(H(M), Крів)

a. v, vii, iI, I, III, IV, vi
b. i, II, II, V, iv, vii, vi
c. I, I, III, IV, V, vi, vil
d. vii, vi, V, iV, III, II, 1

`Answer :- For Answer Click Here`

3. The act of digitally signing transactions by the sender in Blockchain ensures the
resolution of repudiation/verifiability problems.

a. True
b. False

`Answer :- For Answer Click Here`

4. Which of the following is used to point to a block in the blockchain:

a. Hash Pointer
b. User ID
C. Transaction ID
d. Timestamp

`Answer :- `

5. Suppose you have 6 data points — A to F. The post-order traversal of the Merkle
Tree is given by (here A means hash of A, DC means the combined hash of D and
C, and so on):

a. {ABCDEFEF, ABCD, EFEF, AB, CD, EF, EF, A, B, C, D, E, F}
b. {A, AB, B, C, D, CD, ABCD, E, F, EF, ABCDEF}
C. {A, B, AB, C, D, CD, ABCD, E, F, EF, GH, EFGH, ABCDEFGH}
d. {A, B, AB, C, D, CD, ABCD, E, F, EF, EF, EFEF, ABCDEFEF)

`Answer :- `

6. Which of the following is true for using a digital signature in blockchain?

a. To check the validity of the source of a transactions
b. None of the above.
c. It will ensures that no one can deny of their own transaction
d. It supports user authentication

`Answer :- For Answer Click Here`

7. Which are the main Consensus Algorithms?

a. Proof of Work
b. Proof of Wager
c. Proof of Stake
d. Proof of Mining

`Answer :- `

8. Why is consensus hard in an asynchronous system?
1. No notion of global time
II. faults in network
III. nodes may crash/ faulty nodes

`Answer :- `

9. The Liveliness property ensures the output should be produced within a finite time
limit?

a. False
b. True

`Answer :- `

10. Paxos consensus support(s) which of the below properties

a. Liveliness
b. Safety
c. Both
d. None of the above

`Answer :- For Answer Click Here`