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
In Bitcoin's HD wallets (BIP-32), what is the role of the chain code alongside an extended key?
Answer: It provides additional entropy to prevent child key derivation without it
The chain code is 256 bits of extra entropy combined with the key, ensuring child key derivation requires both components to proceed.
Which hash function does Bitcoin use to produce a 256-bit block hash in Proof of Work?
Answer: SHA-256 applied twice (SHA-256d)
Bitcoin applies SHA-256 twice to block headers (SHA-256d) to produce the block hash used in Proof of Work difficulty comparison.
What does 'hardened' child key derivation in BIP-32 prevent compared to 'normal' derivation?
Answer: Prevents leaking the parent private key if a child private key is compromised
Hardened derivation uses the parent private key (not public key) as input, so a compromised child private key cannot be used to derive the parent private key.
Ethereum uses Keccak-256 rather than the standardized SHA-3. What is the key difference?
Answer: Ethereum's Keccak-256 uses different padding than NIST's final SHA-3 standard
Ethereum adopted Keccak before NIST finalized SHA-3 with modified padding; both are sponge constructions but produce different outputs for the same input.
In a threshold signature scheme (e.g., t-of-n multisig via Shamir's Secret Sharing), what must be true to reconstruct the secret?
Answer: Any t shares out of n are sufficient
Shamir's Secret Sharing is designed so that any t (threshold) shares are sufficient to reconstruct the secret, while fewer than t reveal nothing.
What is the purpose of the RIPEMD-160 hash applied after SHA-256 when creating a Bitcoin address?
Answer: To shorten the public key hash to 160 bits for a more compact address
Applying RIPEMD-160 to the SHA-256 hash of the public key produces a shorter 160-bit value, making Bitcoin addresses more compact.
Which statement about symmetric vs. asymmetric cryptography in blockchain is most accurate?
Answer: Asymmetric cryptography handles key pairs for signing; symmetric cryptography may be used for data encryption off-chain
Blockchain transaction signing uses asymmetric (public/private) key pairs, while off-chain data encryption often employs faster symmetric algorithms.