Monero alleviates privacy concerns using the concepts of ring signatures and stealth addresses. Ring signatures enable a sender to conceal their identity from other participants in a group. Ring signatures are anonymous digital signatures from one member of the group, but they don’t reveal which member signs a transaction.
To generate a ring signature, the Monero platform uses a combination of a sender’s account keys and clubs it with public keys on the blockchain. This makes it unique as well as private. It hides the sender’s identity, as it is computationally impossible to ascertain which of the group members’ keys was used to produce the complex signature.
Stealth addresses add additional privacy, as these randomly generated addresses for one-time use are created for each transaction on behalf of the recipient. The use of these stealth addresses enables concealing the actual destination address of a transaction, and it hides the identity of the receiving participant.
Ring Confidential Transactions, or RingCT, also enable hiding the amount of a transaction. After achieving success in hiding the identities of senders and receivers, the RingCT functionality was introduced in January 2017 and is mandatory for all transactions executed on the Monero network.
While privacy fuels the rapid adoption of Monero, it also brings with it several challenges. For instance, the non-traceability and privacy features allow them to be used for disreputable purposes and at questionable marketplaces, including those like drugs and gambling. This is one of the reasons why markets that were popular on the dark web, like AlphaBay and Oasis, showed increased use of Monero before they were shut down.
Reports by CNBC cite the case of hackers creating malicious software that infected computers to mine Monero and send it to North Korea. Monero is essentially open to be used for illicit activities and for evading law enforcement, as it remains outside of capital controls with no traceability.