XZC (ZCoin) has been renamed as FIRO (Firo).

Zerocoin (XZC) is a cryptocurrency that uses the zerocoin protocol to ensure privacy of accounts. It is the first cryptocurrency to implement the Zerocoin protocol, which uses zero-knowledge proofs to ensure that the relevant address information of both parties to the transaction is not leaked. Zcoin is developed by a R&D team headed by Poramin and Aizensou. It uses the zerocoin protocol to protect the privacy of accounts, and uses zero-knowledge proof to ensure that the relevant address information of both parties to the transaction is not leaked. Its parameters are the same as Bitcoin, the block time is 10 minutes, and the output halving cycle is also the same as Bitcoin, which is about once every 4 years.

XZC will be halved in September 2020, and the block reward after halving: 6.25XZC.

Compared to the coin-mixing technology and ring-signature technology that realized the anonymous function in the early stage, the zero-knowledge proof zero-coin protocol solves the shortcomings of the former two and completely cuts off the connection between minted coins and redeemed coins . When you mint a zerocoin, you also burn a zerocoin and generate a proof that you burned a zerocoin. This proof only confirms that you burned a zerocoin, but does not need to prove which one you burned. Then by using this proof, you can redeem a brand new zerocoin with absolutely no transaction history whatsoever.

Project Highlights

Zcoin uses the RSA-2048 parameters from the RSA cracking challenge. The computer hard drive that produced these parameters was destroyed 25 years ago. In the past 25 years, no one has been able to come up with a solution to crack the parameters of RSA-2048, and it is unlikely that anyone will be able to crack it in the next few decades. In the future, Zcoin will switch to another cryptographic scheme that does not require any trust mechanism at all. Bitcoin and some previous altcoins attempted to solve the anonymity problem by using mixers or ring signatures. But they scored poorly on the traceability set metric.

Traceability sets are a key indicator of the anonymity of cryptocurrencies. Traceability sets in remaining solutions are limited by the number of mixes or ring signature size. Each coin mixing or ring signing is limited by the number of transactions in the operation cycle, because the block size of the cryptocurrency is limited. Consequently, the traceability sets in these early anonymity schemes were only in the hundreds.

The metrics of Zcoin's traceability set have been greatly improved. Instead of limiting traceability sets to hundreds, Zcoin adds up all minted coins in the accumulator, increasing traceability set sizes into the thousands. Therefore, it has a higher level of anonymity than mixed coins or ring-signed cryptocurrencies. Another problem is that mixed transactions are only secure under the assumption of lack of topology analysis and pre-existing network data, which is an incorrect threat model. There are many research papers showing that it is possible to break the anonymity of cryptocurrencies using independent network topologies like Facebook, as long as there is a long chain of transaction histories. In all previous cryptocurrencies, a long chain of transactions can be publicly displayed on the blockchain and easily topologically analyzed.

In Zcoin, such a long chain of transaction history does not exist at all. Neither the sender nor the receiver of the transaction need to disclose any information. The sender and receiver have no connection, so it is difficult to perform topology analysis.

Application scenario

Using Zcoin's Zerocoin technology, you can "mint" a coin on the public ledger into a hidden coin, and when you get back your minted coin, you don't need to reveal who minted the coin. The process of retrieving and minting coins can be done as many times as needed, ensuring complete privacy.