CBSE Blockchain Cryptography Fundamentals 2

Question 1

Which property of a cryptographic hash function ensures that finding two different inputs that produce the same hash output is computationally infeasible?

Accepted Answer

Collision resistance

Answer

Collision resistance means it is computationally infeasible to find two distinct inputs x and y such that H(x) = H(y).

Question 2

In elliptic curve cryptography (ECC), the security relies on the hardness of which mathematical problem?

Accepted Answer

Discrete logarithm problem on elliptic curves

Answer

ECC security is based on the elliptic curve discrete logarithm problem (ECDLP), which is harder than the standard discrete log problem for the same key size.

Question 3

A blockchain uses SHA-256 to hash block headers. An attacker wants to find an input that hashes to a specific target value. Which property prevents this?

Accepted Answer

Pre-image resistance

Answer

Pre-image resistance ensures that given a hash output H(x), it is computationally infeasible to find any input x that produces that output.

Question 4

Which of the following best describes a Merkle tree in blockchain?

Accepted Answer

A binary tree where each non-leaf node is the hash of its children

Answer

A Merkle tree is a binary hash tree where each leaf is a transaction hash and each parent node is the hash of its two children, enabling efficient verification.

Question 5

What is the key advantage of using ECDSA over RSA for digital signatures in blockchain systems?

Accepted Answer

ECDSA provides equivalent security with significantly smaller key sizes

Answer

ECDSA achieves equivalent cryptographic security to RSA but with much smaller keys (e.g., 256-bit ECC ≈ 3072-bit RSA), reducing storage and bandwidth overhead.

(CBSE) Certified Blockchain Security Expert Practice Test

(CBSE) Certified Blockchain Security Expert Practice Test

CBSE Blockchain Cryptography Fundamentals 2