Blockchain Basics & Security

Explain the concept of decentralization in blockchain technology.

• Decentralization in blockchain technology refers to the distribution of control and data across a network of computers, rather than relying on a central authority.

• Decentralization in blockchain technology allows for easy manipulation of data by a single entity.

• Decentralization in blockchain technology involves a hierarchical structure with one central node.

• Decentralization in blockchain technology means all data is stored on a single server.

What are the key components of a block in a blockchain?

• Proof of work, Proof of stake, Consensus algorithm

• Block number or height, Nonce, Previous block hash, Timestamp, Merkle root, Data, Block hash

• Public key, Private key, Signature

• Transaction ID, Block size, Miner reward

What is a cryptographic hash function and how is it used in blockchain?

• A cryptographic hash function is a tool in blockchain used to compress large amounts of data.

• A cryptographic hash function is a method in blockchain that allows for easy retrieval of lost data.

• A cryptographic hash function is a mathematical algorithm used in blockchain to secure data by converting it into a unique hash value.

• A cryptographic hash function is a type of encryption used in blockchain to hide data from unauthorized users.

Discuss the role of consensus algorithms in blockchain security.

• Consensus algorithms slow down transaction processing, making blockchain less secure

• Consensus algorithms have no impact on blockchain security

• Consensus algorithms are only used for data storage and retrieval, not security

• Consensus algorithms ensure agreement among nodes on transaction validity and order, enhancing blockchain security.

What is a 51% attack and how does it affect blockchain networks?

• A 51% attack is a feature designed to improve the efficiency of blockchain networks.

• A 51% attack enhances the security of blockchain networks by distributing control evenly among participants.

• A 51% attack has no impact on blockchain networks and is purely theoretical.

• A 51% attack can compromise the security and integrity of blockchain networks by enabling malicious actors to control the majority of the network's mining power.

Which one is not the property of hash functions?

• Efficient

• Easy to invert

• Collision resistant

• Avalanche Effect

In SHA-256, preprocessing phase the message is padded to make its length be a multiple of

• 256

• 512

• 1024

• 128

What is the hardness assumption behind Schnorr Digital signature scheme?

• Decisional Diffie-Hellman Assumption

• Computational Diffie-Hellman Assumption

• Discrete logarithm

• Factoring Assumption

One characteristic/drawback of ElGamal Encryption scheme

• Deterministic

• Unconditional security

• Cipher text is double the size of the plain text

• None of the above

RSA encryption is based on

• One way function

• One way permutation

• One way trapdoor permutation

• All of the above