CCI Cryptocurrency Fundamentals 2

Question 1

A Bitcoin user spends a 1 BTC UTXO to pay 0.3 BTC. In a properly built transaction, where does most of the remaining value go?

Accepted Answer

It is sent to a change address controlled by the sender

Answer

UTXOs must be spent in full, so wallets create a change output back to the sender, and any value left unassigned becomes the miner fee.

Question 2

Which key derivation direction is computationally feasible in Bitcoin?

Accepted Answer

Private key to public key to address

Answer

Elliptic curve multiplication and hashing are one-way functions, so derivation only flows from the private key outward.

Question 3

Which elliptic curve does Bitcoin use for its public-key cryptography?

Accepted Answer

secp256k1

Answer

Bitcoin uses the secp256k1 curve for both ECDSA and Taproot Schnorr signatures.

Question 4

How many words are in the standard BIP-39 English mnemonic wordlist?

Accepted Answer

2048

Answer

BIP-39 uses a 2048-word list, so each word encodes 11 bits of entropy plus checksum.

Question 5

An investigator finds a Bitcoin address beginning with 'bc1p'. What address type is this?

Accepted Answer

Taproot (P2TR)

Answer

Bech32m addresses starting with bc1p are Taproot outputs, while bc1q indicates SegWit v0.

CCI - Certified Cryptocurrency Investigator Practice Test