Blockchain and its Applications Assignment 1 Answers
Blockchain and its Applications Assignment 1 Answers (JAN-APR 2025)
Que. 1) Which of the following statements are true regarding the foundational concepts of blockchain and cryptography? a) Decentralization in blockchain ensures that a single authority controls the network for higher efficiency. b) SHA-256 is a cryptographic hash function widely used in blockchain due to its fixed output size and collision resistance. c) A hash chain is a sequence of cryptographic keys used to decode blockchain data. d) Cryptographic hash ensures that the blockchain data cannot be read by anyone outside the network.
Answer: Updating soon (in progress)
Que. 2) An attacker wants to find a collision in a cryptographic hash function with a 256-bit output. What is the approximate number of hash operations required to succeed? a) 21282^{128}2128 b) 0.75×21280.75 \times 2^{128}0.75×2128 c) 1×21241 \times 2^{124}1×2124 d) 0.5×21280.5 \times 2^{128}0.5×2128
Answer: Updating soon (in progress)
Que. 3) A blockchain network uses SHA-256 for its hashing process. If it takes 10−610^{-6}10−6 seconds to compute a single SHA-256 hash, how long would it take (approximately) to compute 21222^{122}2122 hashes for a collision attack? a) 101010^{10}1010 years b) 101510^{15}1015 years c) 102010^{20}1020 years d) 102510^{25}1025 years
Answer: Updating soon (in progress)
Que. 4) In a decentralized distributed system with 100 participants, which of the following statements is true regarding trust and communication? a) At least 51 participants must trust each other for the system to function. b) A central body governing communication among all 100 participants is mandatory. c) Participants may or may not trust each other, as the system ensures integrity using cryptographic protocols and agreement through consensus protocols. d) All the 100 participants must trust each other.
Answer: Updating soon (in progress)
Que. 5) A blockchain network achieves an average block generation time of 10 minutes under normal conditions. However, due to scheduled maintenance, the network’s hash rate is reduced by 50% for 4 hours daily. If the network operates for 12 hours in total (including the maintenance period), how many blocks will be added to the blockchain? a) 120 b) 200 c) 216 d) 240
Answer: Updating soon (in progress)
Que. 6) Where are the logs stored in a blockchain network? a) In a centralized SQL database. b) On an immutable ledger controlled by a central authority. c) In metadata tables on each peer. d) In the distributed ledger of each peer across the network.
Que. 7) Which of the following describes the avalanche effect in a cryptographic hash function? a) Given the same input, the hash function returns a different hash 99.99% of the time. b) It takes 10510^5105 attempts to reverse-engineer the original message from the hash. c) A small change in the input causes a drastic change in the hash, flipping nearly all the bits. d) The hash function always returns the same hash for the same input.
Answer: Updating soon (in progress)
Que. 8) Which of the following statements accurately describes a blockchain? a) A centralized database where data is stored on a single server. b) A distributed ledger where data is stored across multiple nodes and is immutable. c) A system that only stores cryptocurrency transaction data on a single node. d) A network that uses a single user to control access and updates to the data.
Answer: Updating soon (in progress)
Que. 9) Which of the following is/are possible use cases of blockchain technology? a) Cross-border payments b) Supply chain management c) Centralized anti-money laundering tracking system d) Maintaining data over a single database server
Answer: Updating soon (in progress)
Que. 10) In a blockchain using SHA-256, if the hashes of strings A and B are concatenated and then hashed again, what is the length of the final hash? a) 256 bits b) 512 bits c) 768 bits d) 1024 bits
Answer: Updating soon (in progress)
Blockchain and its Applications Assignment 1 Answers (JAN-APR 2024)
These are Blockchain and its Applications Assignment 1 Answers
Q1. What are the features of a hash function? a. Puzzle-friendly b. Collision-resistance c. Deterministic d. Post image resistance
Answer: a. Puzzle-friendly b. Collision-resistance c. Deterministic
Q2. For a SHA 256 bit hash function, the attacker needs to compute how many hash operations in order to find two matching outputs? a. 0.3 x2^128 b. 0.2×10^50 c. 0.25X2130 d. 1 x2256
Answer: c. 0.25X2130
Q3. What is the hash value of 6666 if SHA-256 is used? a. b. c. d.
These are Blockchain and its Applications Assignment 1 Answers
Q4. Which of the statements below is/are true for decentralized distributed systems? a. Players may or may not trust each other b. Players must trust each other c. Central body should govern the communication d. None of the above
Answer: a. Players may or may not trust each other
Q5. Miner nodes only execute new transactions but can not verify previous transaction hash? a. True b. False
Answer: b. False
Q6. Which of the following is/are true for blockchains? a. Works based on Push technique b. Existing data can be deleted easily c. Tamper-proof d. None of the above
These are Blockchain and its Applications Assignment 1 Answers
Q7. Where are the ledger logs stored in a blockchain? a. On a SQL Database b. On a central immutable ledger c. On a metadata table d. In ledger of each peer
Answer: d. In ledger of each peer
Q8. Which of the following is an avalanche effect to a cryptographic hash function? a. given the same message the hash function would not return the same hash b. it is not very difficult to generate the original message from the hash c. a small change in the message, impacts large change the hash value d. None of the above
Answer: c. a small change in the message, impacts large change the hash value
Q9. Genesis blocks may not contain the a. First transaction b. First transaction block c. Last transaction block d. None of the above
Answer: c. Last transaction block
These are Blockchain and its Applications Assignment 1 Answers
Q10. Which of the below is/are blockchain based app examples? a. Cross-border payments b. Supply chain c. Anti-money laundering tracking system d. UTXO
Answer: a. Cross-border payments b. Supply chain c. Anti-money laundering tracking system
These are Blockchain and its Applications Assignment 1 Answers
Q1) Which one is true for an ideal decentralized solution for business management? a. A centralized authority should decide the overall trust b. Everyone should trust and cooperate with each other c. No one should trust and cooperate with each other d. No one should trust each other, however they should cooperate
Answer: d. No one should trust each other, however they should cooperate
Q2) Which of the statements below is/are true for successful run of decentralized distributed systems? a. Network of different players b. Players must trust each other c. If they cooperate, the society gets benefitted d. None of the above
Q3) Where are the transactions logs recorded in a blockchain? a. Centralized editable database b. Editable log file c. On centralized immutable database d. On append only distributed immutable ledger
Answer: d. On append only distributed immutable ledger
These are Blockchain and its Applications Assignment 1 Answers
Q4) What are the properties of cryptographic hash function? a. It should be deterministic b. It should be collision free c. Ability to hide the input message d. Puzzle friendly
Answer: a, b, c, d
Q5) For a 512 bit hash function, the attacker needs to compute how many hash operations in order to find two matching outputs in the initial round? a. 2512 b. 2128 c. 2256 d. 260
Answer: c. 2256
Q6) Which of the following is a correct statement about a cryptographic hash function? a. given the same message the hash function would not return the same hash b. it is not very difficult to generate the original message from the hash c. a small change in the message, impacts the hash value d. one can easily find two different messages with same hash
Answer: c. a small change in the message, impacts the hash value
These are Blockchain and its Applications Assignment 1 Answers
Q7) What are the security features of a hash function? a. Non-deterministic b. Puzzle-friendly c. Collision-resistance d. Preimage resistance
Answer: b, c, d
Q8) SHA-512 hashing algorithm used by Bitcoin blockchain to determine the hash of a block. This above statement is True or False. a. True b. False
Answer: b. False
Q9) For hash computation in SHA-512, what is the size of the block that the message is divided into? a. 1024 b. 512 c. 256 d. 1248
Answer: a. 1024
These are Blockchain and its Applications Assignment 1 Answers
Q10) What is the message for hash value of “__” if SHA-256 is used? (case sensitive) a. Consensus b. Swayam c. SWAYAM d. Consensus
Answer: a. Consensus
These are Blockchain and its Applications Assignment 1 Answers
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