Qtum was born as a way to bring the best from BTC and ETH but how would you describe the main pillars of the project?
The main pillar is that we are a blockchain ready for business, rather than just a research project. We’ve always prided ourselves on meeting the deadlines we set for ourselves, and having easy to use tools for businesses and developers. We also have been focused on bringing smart contracts to IoT and mobile devices and use cases.
Why bet for POS instead of mining?
We think using an entire country’s usage of electricity on securing the blockchain is incredibly wasteful, and presents a huge barrier to entry for anyone that wants to help secure the blockchain. In Qtum’s PoS model, anyone can stake with as little as 1 Qtum. there is not a limited set of stakers nor is there is a minimum amounts you need to own in order to stake. I feel like this really lives up to Satoshi’s original vision of a truly decentralized blockchain, with participants helping to secure the network all over the world. At last count we have over 3,000 full nodes that hold a copy of the blockchain, and over 15M Qtum is being used right now to secure the network by stakers.
What are the reasons to adopt the UTXO model? As Ethereum refused to implement it due to some limitation concerns.
Ethereum’s account model is very simple and allows a smart contract to only need to worry about 3 things: it can spend coins, it can receive coins, and it has a balance. Despite this simplicity, there are many additional mechanisms that are required in order to keep the model secure. The most limiting aspect of this in Ethereum’s design is the “transaction nonce”. Basically, this limits how transactions can be put into a block that are from a single account. If I send from account A to B, and then again to account C, then the miners must keep that in order. If the miners instead mine the transfer from A to C first, then the transfer from A to B becomes invalid and another transaction must be constructed and mined.
The UTXO model, meanwhile, is much simpler in the security aspect. A UTXO can only be spent or unspent. It’s possible to send from the same address to multiple different accounts, and the order of these transactions is enforced by the blockchain. Miners/stakers can not influence this order. The technical simplicity comes at a cost though. Namely, that a single address can hold multiple UTXOs which make up it’s balance, and in order to minimize transaction fees, the UTXOs to be spent must be picked carefully, and a “change UTXO” must be used. Taking our example from earlier, the UTXO from A must be sent to B, and then also sent back to A for the remaining coins. If another transfer to C is sent, then the coins that were sent back from A would be used. This makes smart contracts incredibly difficult to use in this model, since so much logic must be used to keep track of this.
Our primary innovation that really ties Qtum together though, is a piece of technology we call the Account Abstraction Layer. Basically, this piece of Qtum will give smart contracts an easy to use account model like Ethereum, but when they send or receive coins, the blockchain will convert this to a series of UTXOs. This decouples the smart contract platform from how the underlying blockchain actually works. This allows us to more easily upgrade the underlying blockchain, while keeping the smart contract platform stable and without breaking any smart contracts with our upgrades. This also is the key innovation that allows for us to realize SPV interactions with smart contracts. SPV is a light wallet protocol used by Bitcoin mobile wallets. With this, we’re able to upgrade this protocol so that it can also be used for smart contract interactions.
About the team, what are your strengths?
I think our biggest strength is our experience. Our core team that was built in 2016 didn’t consist of people that knew nothing about blockchain and had to learn. All three of our co-founders had years of experience in this space before coming together to form Qtum. Patrick and Neil both were active in the mining community and made some projects. I was auditing cryptocurrency code to spot scams. John, our marketing director already had some experience with the marketing challenges in the blockchain space. And, Brett, our community manager had been incredibly active in the cryptocurrency community for several years. I believe this gave Qtum a huge head start and is what has allowed us to stay realistic and practical. Patrick specifically is very well known in China, and had went to Draper University. DU has provided us with many early employees and is one of the few places we’ve seen that has had so many people involved in blockchain before the craze of 2017.
What’s the added value of Qtum in comparison with other competitors like NEO?
Our value add is that we’re practical. We’re not some pipe dream project that will be released in 5 years, we’ve been released and stable for several months now, and there are already around 50 Dapps that have been announced for Qtum, with several holding successful crowdsales. We’re also decentralized unlike many projects today. This comes from us using this true PoS model as I discussed earlier. The dBFT model used by so many is significantly more centralized because there are only a set number of nodes that can validate the blockchain, and typically the nodes are elected in a voting system requiring you to hold tens of millions of dollars worth of tokens. NEO specifically only has 7 validating nodes, and they currently control the voting system allowing new nodes to be elected.
Thinking about the future, do you have any roadmap with relevant upgrades?
Yes! 2018 has been a busy year for us already, but I think this will be the year for Qtum. Later this year we will be releasing a new virtual machine for the smart contract platform. This will allow developers and businesses to use proven and established programming langauges and tooling, such as C++, Rust, Go, Python, etc. This also will expose the full power of the Account Abstraction Layer, allowing for contracts to be “tagged” to monitor and witness a transaction it is otherwise not involved in. An aspect I’m especially excited about is that we are building a new database system for use in this VM. This database system is greatly simplfied from how Ethereum’s database works, and is also the first database built specifically for light wallet and SPV smart contract interactions. The most common attack here is information withholding attacks, and our database design closes nearly all attack vectors related to this. The combination of this new datbaase and VM should mean smart contracts that are more economical to execute and to enable use cases that have previously been impractical.
Another thing we are working on is an enterprise version of Qtum. This will be probably early 2019. We want to have a specialized version of Qtum where a business writes a configuration file indicating how their network should be configured, and then they run the program and they instantly have a production-ready private blockchain. Also because of our Account Abstraction Layer, it will be simple to write specialized virtual machines that are tuned exactly to an enterprise’s use case. This also will include our Decentralized Governance Protocol that will allow for companies to receive and hand over control as needed, and to adapt the private blockchain for unexpected external events.
Could you evaluate the current scenario for Qtum and the DApps blockchain industry?
This is the scenario we’ve been building for from the beginning. Our big advantage in this space is that we have built a trustless system, there is no need to rely on a third party server to keep your coins and Dapp state secure. There are already some mobile Dapps that have apps in the app store, but we’re still waiting for the community to catch up to the technology we’ve provided. We think that if your smart contracts will be used heavily on Mobile and IoT devices though, then Qtum is probably the best platform in this space right now.