QTUM Explained

QTUM Explained

Last Updated: 1st November 2018

Qtum is a Singaporean based, open-source project that combines Bitcoin’s Unspent Transaction Output (UTXO) model with the Ethereum Virtual Machine (EVM). The EVM allows for compatibility with Ethereum based smart contracts written in solidity. Through use of its core technology, “Account Abstract Layer”, to bridge Bitcoin Core’s UTXO model and the EVM. The purpose of this is to allow for smart contracts and decentralized applications to operate on the tried and tested foundation of Bitcoin. Qtum employs a proof-of-stake consensus mechanism and currently possess the following specifications:

  • Block time of ~120 seconds
  • Block size of 2MB
  • Maximum supply of 100 million

The aim of of the project is to provide solutions to businesses by combining the best parts of the Bitcoin and Ethereum protocols. With further development, the Qtum foundation aims to be able to market their platform to industries including: Logistics, finance, manufacturing and many more.

Qtum is marketed as the toolkit for developers to use in-order to build robust decentralized applications on top of. However, as opposed to being built using an “Account-based model” like Ethereum is, Qtum is built upon Bitcoin’s UTXO model. In addition, due to the way it is technologically setup, Ethereum smart contracts and Bitcoin Improvement Proposals (BIP) are compatible on the Qtum blockchain.

Account Abstract Layer (AAL)

The Account Abstract Layer serves as a point of contact between the Bitcoin protocol and the Ethereum Virtual Machine. Smart contracts that previously could not be executed in mobile applications or storage devices, would in theory be possible because of the Account Abstract Layer. By stacking the AAL on top of the Bitcoin blockchain, a protocol of the Bitcoin network known as, “Simple Payment Verifications” (SPVs) can be accessed. The SPV protocol allows users to interact with a blockchain without having to download it. It is with the SPV protocol that Qtum uses to power their lite wallet, Go-Mobile.


The purpose of Go Mobile is to be a platform that enables the use of decentralized applications on mobile devices. By utilizing the SPV protocol of Bitcoin’s UTXO model, Qtum is able to use what are known as lite wallets, in-order to communicate with smart contracts and decentralized applications. The immediate benefit of using the SPV protocol is that there becomes no need for a user to download a whole blockchain in-order to interact with it.

In addition, Qtum extends this to IoT devices. Through use of their AAL technology and SVP compatibility, Qtum allows smart devices to sync with the blockchain network without the need of becoming a full node. The ability to interact with decentralized applications via smart devices, is thought to provide a greater incentive for businesses to adopt the technology.