Cryptography and Hashing Flashcards

What is a 'digital signature' in cryptocurrency transactions used to prove?

Answer: That the sender owns the private key corresponding to the sending address

A digital signature proves the sender controls the private key for the address, authorizing the transaction without revealing the key.

Which algorithm is used in Bitcoin to derive a wallet address from a public key?

Answer: SHA-256 followed by RIPEMD-160

Bitcoin applies SHA-256 to the public key then RIPEMD-160 to produce a 160-bit hash used in the wallet address.

What is a 'nonce' in cryptocurrency mining?

Answer: A random number miners adjust to find a valid block hash

Miners increment the nonce value in the block header until the resulting SHA-256 hash meets the network's difficulty target.

What does 'zero-knowledge proof' allow a prover to demonstrate?

Answer: Knowledge of a secret without revealing the secret itself

A zero-knowledge proof lets one party prove they know a value without disclosing any information about the value itself.

In Ethereum, which hashing algorithm is used instead of Bitcoin's SHA-256 for block hashing?

Answer: Keccak-256

Ethereum uses Keccak-256 (a variant of SHA-3) for hashing, including generating Ethereum addresses from public keys.

What is the purpose of 'key stretching' techniques like PBKDF2 or bcrypt in cryptocurrency wallets?

Answer: To slow down brute-force attacks on passwords used to encrypt wallets

Key stretching adds computational cost to password hashing, making brute-force attacks on wallet passwords impractically slow.

What is a 'hash pointer' used for in blockchain data structures?

Answer: A reference that includes both the location and hash of the previous block's data

A hash pointer stores both where data is stored and a hash of that data, enabling tamper detection across the chain.