Are you looking for NPTEL Blockchain and its Applications Assignment 2 Answers and solution here. All weeks solutions of this course available here.
Table of Contents
These are Blockchain and its Applications Assignment 2 Answers( JAN-APR 2025)
1) Alice employs the RSA cryptosystem with the prime numbers I and q—19 to derive her public and private keys. Given that her public key is I, what is her corresponding private key d? Options: [a] 35 [b] 131 [c] 101 [d] 149
Blockchain and its Applications Assignment 2 Answers
3) Digitally signing transactions by the sender in Blockchain ensures the resolution of repudiation and credibility problems. Based on this, which one of the following is correct? Options: [a] It allows the sender to deny the transaction at any point. [b] It ensures that the sender cannot deny the transaction and the recipient can verify its authenticity. [c] It provides encryption but does not verify the sender’s identity. [d] It guarantees the transaction will remain confidential but does not resolve repudiation issues.
4) What is the primary purpose of Alice signing a message with her private key in a blockchain transaction? Options: [a] To encrypt the message [b] To prevent others from reading the message [c] To prove the message came from Alice [d] To hide the contents of the message
5) Consider 6 data points labeled 1 to 6. The post-order traversal of the Merkle Tree is provided as follows (where I represents the hash of data point I, and 43 denotes the combined hash of 4 and 3, and so on): Options: [a] {12345656, 1234, 12.1, 2.34, 3.4, 5656, 56, s, 6} [b] {1.12, 2.3, 4.34, 1234, 6.56, 123456} [c] {1.2, 12, 3, 4, 34, 1234, 5, 6, 56, 5656, 12345656} [d] {1, 2, 12, 3, 4, 34, 1234, 5, 6, 56, 5656, 12345656}
6) Which of the following is used to refer to a block in a blockchain? Options: [a] Future nonce [b] Block size [c] Previous Block Hash [d] Transaction Timestamp
Blockchain and its Applications Assignment 2 Answers
7) Which of the following does not align with the design goals of cryptocurrency development? Options: [a] Decentralization of control and decision-making [b] Immutability of transaction records [c] Centralized control over transactions [d] Transparency and accessibility of transaction data
8) Which of the following statements is/are true regarding Bitcoin and its consensus algorithm? Options: [a] Bitcoin uses Proof of Work (POW) for transaction validation and block addition. [b] Bitcoin operates on a peer-to-peer (P2P) network. [c] Bitcoin uses Proof of Stake (POS) for centralization. [d] Miners are rewarded with transaction fees and block rewards in Bitcoin.
Blockchain and its Applications Assignment 2 Answers
9) What is the primary focus of ‘safety’ in Bitcoin’s protocol? Options: [a] Preventing invalid transactions [b] Ensuring blocks are mined quickly [c] Guaranteeing that only some of the transactions are private [d] Maximizing the number of transactions per block
10) Which of the following is the primary goal of a consensus algorithm in a distributed system? Options: [a] To ensure that all nodes process transactions at the same speed [b] To guarantee that all nodes in the system agree on a single value or state [c] To minimize the number of nodes required for network communication [d] To prevent malicious attacks by encrypting all data transmitted between nodes
Q1. 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: 35
Q2. 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, K_pubA) ii. At Alice: M = E(M’, K_priA) iii. Bob sends the message M’ to Alice iv. The signature along with the message is sent to Alice (M, M’) v. Bob: M’ = E(M, К_рів) vi. Signing the message with his private key: S = E(H(M), К_рів) vii. M = Е(М’, К_рubв) a. v, vii, ii, i, iii, iv, vi b. i, iii, ii, v, iv, vii, vi c. i, ii, iii, iv, v, vi, vii d. vii, vi, v, iv, iii, ii, i
Answer: b. i, iii, ii, v, iv, vii, vi
These are Blockchain and its Applications Assignment 2 Answers
Q3. The act of digitally signing transactions by the sender in Blockchain ensures the resolution of repudiation/verifiability problems. a. True b. False
Answer: a. True
Q4. 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
These are Blockchain and its Applications Assignment 2 Answers
Q5. 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: d. {A, B, AB, C, D, CD, ABCD, E, F, EF, EF, EFEF, ABCDEFEF}
Q6. 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
These are Blockchain and its Applications Assignment 2 Answers
Q7. Which are the main Consensus Algorithms? a. Proof of Work b. Proof of Wager с. Proof of Stake d. Proof of Mining
Answer: a, c
Q8. Why is consensus hard in an asynchronous system? I. No notion of global time II. faults in network IlI. nodes may crash/ faulty nodes a. II, III b. I, II с. I, III d. I, II, II
These are Blockchain and its Applications Assignment 2 Answers (Session: JAN-APR 2022)
Q1. Let Bob wants to send a long message to Alice. Alice should be able to confirm that it was indeed sent by Bob, and Bob later cannot deny that he had sent the message. They also want that nobody else should be able to see its content. Alice and Bob plan to use public key cryptography and cryptographic hashing techniques. Let the key pairs of Alice and Bob be (Pub A, Pri A) and (Pub B, Pri B), respectively.
Let E, D and H be the encryption, decryption and hash functions, respectively. Let M denote the Message and H(M) its digest. Which of the following describes the correct order of steps to be used by Alice to send the digitally signed message. i. At Bob : M’ = E(M, KpubA) ii. At Alice : M = E(M’, Kpria) iii. Bob sends the message M’ to Alice iv. The signature along with the message is sent to Alice (M, M’) v. Bob : M’ = E(M, KpriB) vi. Signing the message with his private key : S = E(H(M), KpriB) vii. M = E(M’, KpubB)
a. i, iii, ii, v, iv, vii, vi b. i, ii, iii, iv, v, vi, vii c. v, vii, ii, i, iii, iv, vi d. vii, vi, v, iv, iii, ii, i
These are Blockchain and its Applications Assignment 2 Answers
Q2. Digitally signing transactions by sender in Blockchain does not ensure to solve repudiation/verifiability problems. Is the above statement True or False? a. True b. False
Answer: b. False
These are Blockchain and its Applications Assignment 2 Answers
Q3. Which of the following is used to point a block in blockchain : a. Hash Pointer b. User ID c. Transaction ID d. Timestamp
Answer: a. Hash Pointer
Q4. Suppose you have 6 data points — 1 to 6. The post-order traversal of the Merkle Tree is given by (here 8 means hash of 8, 43 means the combined hash of 4 and 3, and so on) : a. {12345656, 1234, 5656, 12, 34, 56, 56, 1, 2, 3, 4, 5, 6} b. {1, 12, 2, 3, 4, 34, 1234, 5, 6, 56, 123456} c. {1, 2, 12, 3, 4, 34, 1234, 5, 6, 56, 78, 5678, 12345678} d. {1, 2, 12, 3, 4, 34, 1234, 5, 6, 56, 56, 5656, 12345656}
These are Blockchain and its Applications Assignment 2 Answers
Q5. 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 given options c. It will ensures that no one can deny of their own transaction d. It supports user authentication
Answer: a, c
Q6. Which are the main Consensus Algorithms? a. Proof of Work b. Proof of Wager c. Proof of Stake d. Proof of Mining
Answer: a, c
These are Blockchain and its Applications Assignment 2 Answers
Q7. Why is consensus hard in asynchronous system? I. No notion of global time II. faults in network III. nodes may crash/ faulty nodes a. II, III b. I, II c. I, III d. I, II, II
Answer: d. I, II, II
These are Blockchain and its Applications Assignment 2 Answers
Q8. Liveliness property ensures the output should be produced within a finite time limit? a. False b. True
Answer: b. True
These are Blockchain and its Applications Assignment 2 Answers
Q9. Paxos consensus support(s) which of the below properties a. Liveliness b. Safety c. Both d. None of the above
Answer: b. Safety
Q10. Which is/are true for Raft consensus? a. Crash Fault Tolerant b. Byzantine Fault Tolerant c. Both d. None of the above
Answer: b. Byzantine Fault Tolerant
These are Blockchain and its Applications Assignment 2 Answers
More Solutions of Blockchain and its Applications: Click Here
