Cryptography in Blockchain Flashcards
7 cards from real Blockchain Technology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Cryptography in Blockchain flashcards as text
What is a Merkle tree used for in blockchain?
Answer: Efficiently verifying the integrity of transaction sets
A Merkle tree hashes pairs of transactions recursively, producing a single root hash that lets nodes verify any transaction without downloading the full block.
Which property of a cryptographic hash function ensures that two different inputs cannot produce the same output?
Answer: Collision resistance
Collision resistance means it is computationally infeasible to find two distinct inputs that hash to the same digest.
In Elliptic Curve Cryptography (ECC), the 'discrete logarithm problem' refers to the difficulty of:
Answer: Finding the scalar k given the points k·G and G on the curve
Given the public point k·G and base point G, recovering the private scalar k is computationally infeasible, forming the security basis of ECC.
What does the 'r' component of an ECDSA signature represent?
Answer: The x-coordinate of a random point on the elliptic curve
In ECDSA, a random nonce k is chosen, and r is the x-coordinate of the point k·G modulo the curve order.
Why is nonce reuse catastrophic in ECDSA?
Answer: It allows an attacker to compute the private key from two signatures
If the same nonce k is used for two different messages, the private key can be algebraically derived from the two signature pairs.
Which of the following best describes a zero-knowledge proof in a blockchain context?
Answer: Proving knowledge of information without revealing the information itself
A zero-knowledge proof lets a prover convince a verifier that a statement is true without disclosing any underlying secret data.
What is the primary purpose of a Key Derivation Function (KDF) like PBKDF2 in blockchain wallets?
Answer: Strengthening a user password before using it as cryptographic key material
KDFs add computational cost (iterations, salting) to slow brute-force attacks when deriving encryption keys from user passwords.