Cryptocurrency Cryptography and Hashing 5

Question 1

What is a 'ring signature' used for in privacy-focused cryptocurrencies like Monero?

Accepted Answer

To allow a user to sign a transaction on behalf of a group without revealing which member signed

Answer

Ring signatures let a signer produce a signature verifiable as coming from a group while hiding which specific group member actually signed.

Question 2

What is the primary purpose of the ECDSA (Elliptic Curve Digital Signature Algorithm) in Bitcoin?

Accepted Answer

To generate and verify transaction signatures proving ownership of funds

Answer

ECDSA is used to create digital signatures for Bitcoin transactions, allowing nodes to verify the sender owns the referenced UTXOs.

Question 3

What is 'replay protection' in the context of cryptographic transaction signing during a blockchain hard fork?

Accepted Answer

A mechanism ensuring a signed transaction on one chain cannot be rebroadcast on a forked chain

Answer

Replay protection modifies transaction signing to include chain-specific data, so a valid transaction on one fork is invalid on the other.

Question 4

What distinguishes a 'trapdoor function' from a regular one-way function in public-key cryptography?

Accepted Answer

A trapdoor function can be reversed only with a special secret (private key)

Answer

A trapdoor function is easy to compute forward and hard to reverse, except for someone who knows the secret trapdoor — the private key.

Question 5

What is the 'difficulty target' in Bitcoin mining, and how does hashing relate to it?

Accepted Answer

A threshold the block's SHA-256 hash must be numerically below to be accepted

Answer

Miners must find a nonce such that the block header's double SHA-256 hash is less than the current difficulty target, a number with many leading zeros.

Cryptocurrency Practice Test

Cryptocurrency Practice Test

Cryptocurrency Cryptography and Hashing 5