Qtum
Qtum
Token: QTUM


The Blockchain Made Ready for Business

ICO dates
Start date: 2017-03-12
End date: 2017-03-17

Registrated in: Singapore

Platform: Ethereum

PREMIUM ICO

HARA

Empowering billions by utilizing a global and transparent data exchange.
Ends in 49 days 22 hours
Goal: 17,000,000 USD
Price: 1 HART = 0.059 USD

Dominium

Dominium Blockchain – The one-stop-platform for everything to do with property anywhere in the world!
Ends in 18 days 22 hours
Goal: 17,500,000 USD
Price: 1 DOM = 0.25 EUR
Qtum categories
Business services Cryptocurrency
Qtum whitepaper
Video
Qtum token sale
KYC passing required No | Whitelist No | Restriction for countries No
Tokens for sale 51,000,000
Sold tokens 51,000,000
Acceppting BTC, ETH
Qtum news, social
Qtum search trends in Google
Random whitepaper excerpts

2
Alex Norta
ing a trusted central authority. Blockchain technology spreads in popularity with
the inception of Bitcoin [23], a peer-to-peer (P2P) cryptocurrency and payment
system that comprises a limited set of operations on the protocol layer. Bit-
coins use PoW for transaction validation that is computationally expensive and
electricity intensive.
In contrast to Bitcoins, many smart-contract systems are equipped with the
Turing-complete language Solidity
1
that resembles JavaScript syntax and targets
for enactment, e.g., the Ethereum Virtual [44] machine. Ethereum is the de-
facto leading smart-contract system despite being plagued by several deficiencies.
First, proof-of-work transaction validation diminishes scalability to the point
where Ethereum is considered to not be feasible for most industry applications.
Second, in a recent crowdfunding casestudy, the Ethereum affiliated Solidity
smart contract was hacked
2
because of security flaws resulti...

Smart-Contract Information- & Value Logistics
3
While smart-contract systems such as Ethereum attract attention, a widespread
industry adoption does not exist for the above discussed reasons. This whitepa-
per addresses the gap by specifying the Qtum
6
framework for smart-contract
systems that answers the question of how to develop a smart-contract solu-
tion to satisfy critical customer requirements for enabling cross-organizational
information logistics to reduce costs and time? To establish a separation of con-
cerns, we pose the following sub-questions. What differentiating technological
performance advantages do Qtum smart-contract solutions provide? What are
critical smart-contract requirements the Qtum framework satisfies? What are
the unique features of cross-organizational information logistics automation the
Qtum framework aims to support?
The remainder of this whitepaper is structured as follows. First, Section 2
focuses on concrete advantages of the Qt...

4
Alex Norta
2.1 UTXO Versus Account Model
In the UTXO model, transactions use as input unspent Bitcoins that are de-
stroyed and as transaction outputs, new UTXOs are created. Unspent transac-
tion outputs are created as change and returned to the spender [1]. In this way,
a certain volume of Bitcoins are transferred among different private key owners,
and new UTXOs are spent and created in the transaction chain. The UTXO of a
Bitcoin transaction is unlocked by the private key that is used to sign a modified
version of a transaction. In the Bitcoin network, miners generate Bitcoins with a
process called a coinbase transaction, which does not contain any inputs. Bitcoin
uses a scripting language for transactions with a limited set of operations
7
. In
the Bitcoin network, the scripting system processes data by stacks (Main Stack
and Alt Stack), which is an abstract data type following the LIFO principle of
Last-In, First-Out.
In the Bitcoin client, the developer...

Smart-Contract Information- & Value Logistics
5
the occurrence of complex payment conditions, e.g., generating infinite loops, or
other complicated logic loopholes.
In the UTXO model, it is possible to transparently trace back the history of
each transaction through the public ledger. The UTXO model has parallel pro-
cessing capability to initialize transactions among multiple addresses indicating
the extensibility. Additionally, the UTXO model supports privacy in that users
can use Change Address as the output of a UTXO. The target of Qtum is to
implement smart contracts based on the innovative design of the UTXO model.
Versus the UTXO model, Ethereum is an account based system
8
. More pre-
cisely, each account experiences direct value- and information transfers with state
transitions. An Ethereum account address of 20 bytes comprises a nounce as a
counter for assuring one-time processing for a transaction, the balance of the
main internal crypto fuel for paying t...

6
Alex Norta
In the Bitcoin network, miners participate in the verification process by hash
collision through PoW. When the hash value of a miner is able to calculate and
meet a certain condition, the miner may claim to the network that a new block
is mined:
M
Hash
(
BlockHeader
)

D
For the amount of miners
M
and the mining difficulty
D
, the
Hash()
represents
the SHA256 power with value range [0, M], and D. The SHA256 algorithm used
by Bitcoin enables every node to verify each block quickly, if the number of
miners is high versus the mining difficulty.
The 80 byte BlockHeader varies with each different Nonce. The overall dif-
ficulty level of mining adjusts dynamically according to the total hash power
of the blockchain network. When two or more miners solve a block at the same
time, a small fork happens in the network. This is the point where the blockchain
needs to make a decisio...

Smart-Contract Information- & Value Logistics
7
2.3 Qtum Contract and EVM Integration
The EVM is stack-based with a 256-bit machine word. Smart contracts that run
on Ethereum use this virtual machine for their execution. The EVM is designed
for the blockchain of Ethereum and thus, assumes that all value transfer use
an account-based method. Qtum is based on the blockchain design of Bitcoin
and uses the UTXO-based model. Thus, Qtum has an account abstraction layer
that translates the UTXO-based model to an account-based interface for the
EVM. Note that an abstraction layer in computing is instrumental for hiding
the implementation details of particular functionality to establish a separation
of concerns for facilitating interoperability and platform independence.
EVM Integration:
All transactions in Qtum use the Bitcoin Scripting Lan-
guage, just like Bitcoin. In Qtum however, there exist three new opcodes.

OP_EXEC
: This opcode triggers special processin...

8
Alex Norta
Fig. 1.
Qtum transaction processing.
are spent whenever the contract uses the
suicide
operation to remove itself
from the blockchain.
Qtum Account Abstraction Layer
The EVM is designed to function on an
account-based blockchain. Qtum however, being based on bitcoin, uses a UTXO-
based blockchain and contains an Account Abstraction Layer (AAL) that allows
the EVM to function on the Qtum blockchain without significant modifications
to the virtual machine and existing Ethereum contracts.
The EVM account model is simple to use for smart-contract programmers.
Operations exist that check the balance of the current contract and other con-
tracts on the blockchain, and there are operations for sending money (attached
...

Smart-Contract Information- & Value Logistics
9
to data) to other contracts. Although these actions seem fairly basic and mini-
malistic, they are not trivial to apply within the UTXO-based Qtum blockchain.
Thus, the AAL implementation of these operations may be more complex than
expected.
A Qtum-blockchain deployed smart contract is assigned and callable by its
address and comprises a newly deployed contract balance set to zero. There is
currently no protocol in Qtum that allows a contract to be deployed with a
non-zero balance. In order to send funds to a contract, a transaction uses the
OP_EXEC_ASSIGN
opcode.
The example output script below sends money to a contract:
1 ; t h e v e r s i o n o f t h e VM
10000; gas
limit
for the
transaction
1 0 0 ; g a s p r i c e
in
Qtum s a t o s h i s
0xF012 ; data to send the contract
( u s u a l l y
using
t h e S o l i d i t y ABI )
0x1452b22265803b201ac1f8...

Qtum Roadmap

1
Testnet Release (June 2017)
Potentially incomplete GUI, full RPC methods for contract interaction. Designed for developers, not consumers.
2
Mainnet release (September 2017)
GUI for smart contract interaction in wallet. Stable RPC layer for developers.
3
Qtum integration and API release
APIs for interaction with smart contracts for JavaScript, iOs and Android. Release of Qloha, a WeChat wallet for mobile use. Release of SpringMail, email integration for Qtum. Smart contract lifecycle management.
4
Extending Qtum for the future (2018 and beyond)
Each extention will be formally evaluated and timeframe determined with community input guiding priorities. Adding new features and power to the Qtum AAL. First Class Oracles - Native Oracle support on the blockchain beyond standard smart contracts. Support of community projects built on Qtum.
5
New VM implementations on Qtum
Adding new VMs beyond EVM. eSML, a new smart contract language with formal verification.
Stella Kung
Stella Kung
CMO of QTUM
Alex Dulub
Alex Dulub
Blockchain Architecture Advisor
Patrick Dai
Patrick Dai
Co-Founder
Founder of QTUM Blockchain
Investor and Project Advisor
Founder of Qtum