Practice Test Geeks(CBSE) Certified Blockchain Security Expert Practice Test
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Blockchain Cryptography Fundamentals Flashcards

7 cards from real CBSE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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

    Answer: Collision resistance

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

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

    Answer: Discrete logarithm problem on elliptic curves

    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.

  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?

    Answer: Pre-image resistance

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

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

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

    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.

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

    Answer: ECDSA provides equivalent security with significantly smaller key sizes

    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.

  6. In ECDSA signature generation, reusing the same nonce k for two different messages with the same private key results in:

    Answer: Exposure of the private key to any observer

    If the same nonce k is used to sign two different messages, an attacker can solve for the private key algebraically using the two signature equations.

  7. Which cryptographic primitive is used in Bitcoin's Proof-of-Work to create a target-meeting hash?

    Answer: SHA-256 applied twice (SHA-256d)

    Bitcoin's Proof-of-Work uses double SHA-256 (SHA-256 of SHA-256) on the block header to produce a hash that must be below the network difficulty target.