CCI - Certified Cryptocurrency Investigator Privacy Coins and Anonymity Questions and Answers

Question 1

An investigator traces illicit funds to a Zcash address. However, upon examining the transaction on a block explorer, the sender, receiver, and amount are all encrypted. This indicates the funds were sent to which type of address?

Accepted Answer

A z-address (shielded)

Answer

Zcash has two types of addresses: transparent (t-addresses), which are public and traceable like Bitcoin, and shielded (z-addresses), which use zero-knowledge proofs (zk-SNARKs) to encrypt transaction details. When sender, receiver, and amount are obscured, it signifies a transaction involving a shielded z-address.

Question 2

Which privacy-enhancing technology, central to Monero, makes it computationally infeasible for an outside observer to determine which of a group of possible signers actually authorized a transaction?

Accepted Answer

Ring Signatures

Answer

Ring signatures are a cryptographic method used by Monero that mixes a user's transaction with a number of other outputs (decoys) from the blockchain. This creates a 'ring' of plausible signers, making it impossible to determine the true origin of the transaction without additional information.

Question 3

An investigator analyzing the Bitcoin blockchain encounters a single large transaction with numerous inputs and outputs of identical value. This structure makes it difficult to apply the common-input-ownership heuristic. Which privacy technique was most likely used?

Accepted Answer

CoinJoin

Answer

CoinJoin is a method where multiple users combine their transactions into a single, larger transaction to obscure the original flow of funds. By mixing multiple inputs and outputs, it breaks the link between a specific sender and receiver, frustrating blockchain analysis.

Question 4

What is the primary function of a "stealth address" as implemented in privacy coins like Monero?

Accepted Answer

To generate a unique, one-time public address for each transaction to protect the recipient's privacy.

Answer

Stealth addresses are used to protect the privacy of the transaction recipient. For every transaction, a new, single-use address is created that is only accessible by the recipient. This prevents an outside observer from linking multiple payments to the same person's public address.

Question 5

A Certified Cryptocurrency Investigator is assigned a case where a ransomware payment was made using Monero. The victim provides the transaction ID. What is the most significant challenge the investigator will face when attempting to trace the funds on the public ledger?

Accepted Answer

The sender's address, recipient's address, and transaction amount are all obscured by default.

Answer

Monero is private by default, meaning every transaction automatically uses Ring Signatures (hiding the sender), Stealth Addresses (hiding the receiver), and RingCT (hiding the amount). Therefore, even with a transaction ID, an investigator cannot see the critical details of the transaction on the public blockchain, making it extremely difficult to trace.

CCI - Certified Cryptocurrency Investigator Practice Test

CCI - Certified Cryptocurrency Investigator Practice Test

CCI - Certified Cryptocurrency Investigator Privacy Coins and Anonymity Questions and Answers