BLOCKCHAIN AND ITS APPLICATIONS... WEEK 2 ASSIGNMENT NPTEL 2022

 1) Suppose you have eight data points --8 to 1.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):

solution) a) 

2) Which of the following is used to point a block in block chain:

solution) a) Hash pointer

3) Digital signing of a transaction or document involves the hashing  the content of the document and then _________.

solution) a) encrypting it with private key.

4) What is the objective of using digital signature?

solution) c) it supports both user authentication and integrity  of messages.

5) Digitally signing the transactions by sender in Blockchain does not ensure to solve repudiation/verifiability problems. Is the above statement true or false?

solution) b) false

6) Which are the main Consensus algorithms?

solution) a) Proof of work 

               b) Proof of stake

7) Which statement is correct from Fisher -Lynch-Paterson impossibility result:

i) Consensus is impossible even with a single faulty node

ii) Ensures safety and liveliness together

solution) b) only i

8) Why is consensus hard?

l. no notion of global time.

ll. faults in network

lll. nodes may crash/faulty nodes.

solution) a) i ii iii

9) In a RSA cryptosystem Alice uses two prime numbers p=7 and q=17 to generate her public and private keys. If public key of Alice is 11 then private key of Alice is _______.

solution)  35

10) A popular public-private key implementation known as Rivest-Shamir-Adelman(RSA) algorithm is used  for the Bitcoin and Ethereum Blockchain .True or false?

solution) b) False