Frequently Asked Questions

Overview

The wallet is available for download here: https://github.com/zcoinofficial/zcoin

As with any other technology, Zcoin can be used for both good and evil. However, we are firm believers that the net good for Zcoin far outweighs the bad. Throughout history, freedom of commerce has been shown to prevent wars, promote prosperity, and increase cross-culture exchange.

Zcoin is designed to benefit legitimate users who have realized the risk of using a cryptocurrency with a completely transparent public ledger, and the danger of having all their financial details made public with Bitcoin. Because there are already pre-existing mechanisms for such activities, Zcoin does not affect the status quo for such activities, while it provides notable benefits to legitimate users.

Even without Zcoin, such transactions can take place via existing financial systems (e.g. by using cash. Although not actually private, Bitcoin has faced the scrutiny of regulators with its potential use in money laundering.

The Zerocoin Protocol, created in 2013, was originally meant to be an extension on top of Bitcoin. There was a lot of support for Zerocoin from key members of the Bitcoin community. However, Bitcoin has the primary goal of ensuring stability in its money supply, by moving slowly with only unanimously agreed upon changes. As a result of the political deadlock, the Zcoin project was created.

Zcoin strives to increase individual liberty. By guaranteeing financial privacy, Zcoin can help ensure freedom of commerce. People should be able to transact however they want, as long as it does not infringe on the well-being or individual liberty of others. We are also big believers that freedom of commerce also facilitates peace and prosperity across countries and cultures. By guaranteeing financial privacy, Zcoin can directly guarantee fungibility, an essential property for free commerce.

Economics

The Founders Reward will be given to early investors, developers, and Zcoin community members. We also have bounties for various tasks, such as Zcoin core development, web development, graphic design, marketing, ect. If you’d like to help out, please email or message us on Slack.

There will be 21 million Zcoins. Zcoin follows the same halving cycle as Bitcoin (every 4 years). 10% of the total Zcoin supply will be distributed to the Founders Reward as time passes. In the first 4 years, 20% of Zcoins will be distributed to the Founders Reward. In other words, during the first 4 years, 40 Zcoins will go to the miners and 10 Zcoins will go towards the Founders reward. After the first 4 years, the block reward goes completely towards the miners.

Mining

Zcoin uses the ASIC-resistant Lyra2 key derivation function.

Lyra2 is designed for democratic mining, and is currently a very CPU friendly mining algorithm.

The parameters for Lyra2 are as follows:

Lyra2(T=2,R=Block_Height,C=256)

Technical

Zcoin uses the RSA-2048 number from the RSA factoring challenge. The computer’s hard drive which generated the factors were destroyed over 25 years ago. No factoring solution to the RSA-2048 number has been found for the past 25 years, and it is unlikely to be factored in the next several decades. In the long term, Zcoin would eventually shift to a different cryptographic scheme for its setup parameters.

Bitcoin and preceding alternative cryptocurrencies have attempted to solve this problem through the use of transaction mixers or ring signatures. But in the end of the day, they score very poorly on this metric called the traceability set. The traceability set is a key metric to understanding how private a cryptocurrency is. The traceability set in formerly proposed solutions is limited by the size of the mixing cycle or ring signature. Each mixing cycle or ring signature is limited by the number of transactions per cycle, which is transitively limited by the the block size of the cryptocurrency. Thus, the traceability set in previous attempts at privacy tends to only be a few hundred.

With ZCoin, the traceability set is on a dramatically higher magnitude. Instead of having a traceability set limited to the few hundreds, ZCoin has a traceability set that encompasses all minted coins in the ZCoin system. Thus, the magnitude of the traceability could be in the order of millions, rather than hundreds. So its privacy level is magnitudes higher than all previous cryptocurrency.

The other problem is that tumbling methods are only secure under the assumption of a lack of topological analysis and pre-existing network data, which is an incorrect threat model. As I mentioned earlier, there have been multiple research papers demonstrating that taking a separate network topology like Facebook can be used to de-anonymize a cryptocurrency as long as a long chain of transaction history exists. With all previous cryptocurrencies, a long chain of transactions is publicly viewable on the blockchain and prone to topological analysis.

With ZCoin, this long chain of transaction history simply does not exist, and there is zero information leakage about the sender and receiver of a transaction, so it is not prone to topological analysis and so the link between the sender and receiver disappears.

Zcoin’s zero-knowledge proof makes a cryptographic statement. When someone is sent Zerocoin, the person only knows that X amount of money was sent to their wallet. Unlike Bitcoin, there is no other unintended identifying information about the sender and receiver. Zero Knowledge proofs ensure that there is zero information leakage about the sender and receiver of a transaction.

A zero-knowledge proof is a method in which one person can prove to another person that a given statement is true, without conveying any information apart from the fact that the statement is indeed true.
The classic example of a zero knowledge challenge is called Yao’s Millionaire problem: how can two people determine who is richer without either person having to reveal how much money they have? Through a complex application of cryptography, it’s actually possible to do.
Craig Gidney , writing for the Twisted Oak Studios blog, provides a simplified version of the problem that can help you understand the process. In Gidney’s example, two workers — Bob and Alice — want to determine whether they’re being paid the same amount, without disclosing how much they’re being paid to each other or anyone else. The example assumes that Bob and Alice know that they’re each being paid exactly $10, $20, $30, or $40 per hour.
Bob goes and buys four anonymous comment card boxes — the kind a restaurant might have to gather opinions from customers. He labels each one $10, $20, $30 or $40, then throws away all the keys, except the one to the box that corresponds to how much money he makes. Alice then writes “Yes” on one slip of paper and “No” on three others. She puts the “Yes” slip in the box that matches her wage, and the “No” slips in all the others. Once Alice is gone, Bob can then open his box and see if the slip inside reads “Yes” or “No.” If “Yes,” then he and Alice are paid the same wage. If “No,” they will then know that their wages are different.
This example is obviously over simplified. Zerocoin is far more complex, and includes various protections to keep anyone from cheating. But it uses a variation of this same type of thinking.

Zerocoin was one of the most cited cryptography papers in the last 3 years, with over 200 citations. The cryptography principles behind Zerocoin are well-understood and battle-tested. Zerocoin uses zero-knowledge proofs to ensure that zero information is leaked regarading sender and receivers of Zerocoin.

To best understand how blockchain-tracking software works, it helps to view Bitcoin as a kind of financial social network. The same kinds of mechanisms used to break privacy in social networks, by analyzing social network topology, can be used to break privacy in the Bitcoin network. By taking a pre-existing social network like Facebook, we can use that information to generate heuristics about who is transacting with whom on Bitcoin.

There is a relevant research paper that attempted to identify twitter users by using data from flickr. They took the twitter data, and stripped away all identifying information about the user such as name or username. Then, by looking at the social network topology of the anonymized twitter data and comparing it to the flickr data, they found that they could identify one third of twitter users, even though the twitter data was anonymized.

This research also applies to Bitcoin. If we take an anonymous network such as Bitcoin, and use data from a social network from Facebook, we can use topological analysis to identify a lot of users.

Community

Please see: blog here

Resources

Anything else?