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PrettiSmart: Visual Interpretation of Smart Contracts via Simulation

Xiaolin Wen¹

Tai D. Nguyen²

Yong Wang¹

Lun Zhang³

Jun Sun²

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Smart Contract

Traditional Contract

Sellers

Buyers

Contract

Third Parties

Execution

Smart Contract

Blockchain

Sellers

Buyers

Execution

Remove the need for third parties
More efficient and accurate
Immutable: cannot be altered
Code are available on the blockchain

Before we get into what smart contracts are, let’s quickly look at how traditional contracts work.

Usually, buyers and sellers come together and sign a contract. But to actually make it happen—like making sure everyone follows the rules—they often need a third party, like a bank, a government agency, or a big company, to step in and oversee everything.�This whole process can be a bit slow, complicated, and sometimes even risky if the third party isn’t fully reliable.

Now, smart contracts work in a totally different way.

They’re basically computer programs that run on the blockchain. Once certain conditions are met, the contract just runs by itself—no need for a middleman.

This makes things faster and more accurate, because it’s all automatic.�Plus, smart contracts can’t be changed once they’re on the blockchain, so they’re pretty secure.�And since the code is out there for everyone to see, it adds a level of transparency that builds trust.

Before we talk about smart contract, lets see what is traditional contract.�Traditional contracts often require the sellers and buyers to make the contract first, then they need a third party to supervise and execute it, such as government, bank, and big companies.

This maybe a little tedious, time-consuming, and not that reliable.

While, smart contract are predefined programs run on the blockchain, and automatically executed when some conditions are met.

It can help remove the need for the third parties, and more efficient and accurate since it is automatic programs.

Smart contracts are deployed on blockchain and no one can change it, so it is kind of safe.

And the source code are available on the blockchain, every one can check it, so it is kind of reliable.

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Why do we need to visually interpret it?

The source code is available!

Highest Profit!

Zero Risk!

Scam Impossible!

Code is too complex!

No Existing Transactions!

Investors

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Smart Contract

Source Code

Ethereum Blockchain

Smart Contract

Function Calls (Money Transfers)

Send Money (Internal Transactions)

Change State Variables

Change Balances

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PrettiSmart

Possible Function Calls

What we do?

Owner

Multiple Users

Cryptocurrency Flows

Balance Changes

-100

F1

-20

F1

-80

F2

+200

F0

State Variable Changes

Variable #

Smart Contract

Investors

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PrettiSmart

Input

Output

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PrettiSmart

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Simulation Overview

provides a visual summary for each simulation, involving the net balances over time and the involved functions

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Function Summary

shows the statistics of the calls of each function in a simulation.

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Function Call Details

Function Calls

Money Flows

Net Balance

demonstrates the detailed behaviors of the smart contract after each function call

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State Variable Changes

Increase

Decrease

shows how the state variables are changing after each function call.

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Evaluation

Case 1: Interpreting a Gambling Contract

Case 2: Identifying a Fraudulent Smart Contract

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Evaluation

Case 1: Interpreting a Gambling Contract

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Evaluation

Case 1: Interpreting a Gambling Contract

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Evaluation

Case 1: Interpreting a Gambling Contract

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Evaluation

Case 1: Interpreting a Gambling Contract

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Evaluation

Case 1: Interpreting a Gambling Contract

F0: enter (send money to contract)

F1: pickWinner (send money to one user)

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Evaluation

Case 1: Interpreting a Gambling Contract

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Evaluation

User Interviews with 12 cryptocurrency investors

PrettiSmart is effective and useful for investors to analyze the smart contract’s functionality.

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Take-away Message

Smart contract simulation is more easy to understand than the source code for investors.

Visual interpretation of smart contracts is an intuitive way to inform investors of how a smart contract works.

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PrettiSmart: Visual Interpretation of Smart Contracts via Simulation

Xiaolin Wen¹

Tai D. Nguyen²

Yong Wang¹

Lun Zhang³

Jun Sun²

Paper Link

Contact Me!

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PrettiSmart: Visual Interpretation of Smart Contracts via Simulation

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Evaluation

Case 1: Interpreting a Gambling Contract

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Evaluation

Case 2: Identifying a Fraudulent Smart Contract

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Evaluation

Case 2: Identifying a Fraudulent Smart Contract

F0: buyMessage

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Evaluation

Case 2: Identifying a Fraudulent Smart Contract

F1: ownerWithdraw

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