EVM Bytecode Decompiler

A web-based tool for decompiling Ethereum Virtual Machine (EVM) bytecode into human-readable assembly-like instructions, featuring interactive workflow visualization and security analysis capabilities.

Steps to Set Up the Project:

Install Node.js and npm: Ensure you have Node.js and npm installed on your machine. You can download them from nodejs.org.

//Create the Project Directory: Create a directory for your project and navigate into it: mkdir evm-bytecode-decompiler cd evm-bytecode-decompiler

// Then npm init -y

// Install Dependencies: Install the dependencies listed in package.json: npm install

// Run the Project Locally: Use the http-server script to serve your project locally: npm start

This will start a local server, and you can access your decompiler by navigating to http://localhost:8080 in your web browser.

Full Project Structure: evm-bytecode-decompiler/ ├── index.html ├── styles.css ├── mermaid.css ├── mermaid.js ├── decompiler.js ├── pentest.js ├── package.json └── package-lock.json

Features

• Bytecode Decompilation: Converts hex EVM bytecode into readable opcode instructions with definitions
• Interactive Workflow Visualization: Mermaid flowchart showing contract execution flow with stage-by-stage highlighting
• Security Analysis: Built-in pentest simulations for common vulnerabilities:
  • Reentrancy attacks
  • Integer overflow/underflow
  • Front-running susceptibility
  • Access control issues
  • Transaction ordering dependencies (MEV)
• Wallet Integration: Connect Ethereum wallets via MetaMask/Web3 providers
• Contract Analysis: Identifies contract type, features, and security properties
• External Tool Integration: Send bytecode to external converters (EVM to RISC-V, etc.)
• Responsive Design: Works on desktop and mobile devices

Project Structure

.
├── index.html          # Main application interface
├── mermaid.js          # Mermaid initialization and stage control logic
├── mermaid.css         # Styling for Mermaid diagrams and UI components
├── pentest.js          # Security simulation functions
├── .vscode/            # VS Code settings
└── README.md           # This file

How to Use

1. Open the Application: Simply open index.html in any modern web browser (Chrome, Firefox, Safari, Edge recommended)

2. Decompile Bytecode:

   • Paste EVM bytecode (hex format, with or without 0x prefix) into the "Input Bytecode" textarea
   • Click the "Decompile" button to see the decompiled output
   • View analysis in the "Bytecode Analysis" and "Contract Information" panels

3. Visualize Contract Flow:

   • The Mermaid flowchart in the workflow panel shows the typical contract execution flow
   • Use the stage buttons (►) to highlight different execution phases:
     1. Call Received
     2. Read / Validate
     3. State Change
     4. External Call
     5. Return / Emit

4. Run Security Tests:

   • Use the pentest suite buttons to analyze the bytecode for common vulnerabilities:
     • Simulate Reentrancy
     • Simulate Integer Overflow
     • Simulate Front-running
     • Simulate Access Control Bypass
     • Simulate Tx-Ordering (Nonce/MEV)

5. Connect Wallet (Optional):

   • Click "Connect Wallet" to link your Ethereum wallet (requires MetaMask or similar)
   • Enter a contract address and click "Get Bytecode" to automatically fetch bytecode from the blockchain

6. Use External Converter:

   • Click the "EVM→RISC-V Converter" button to open the external conversion tool
   • Your current bytecode will be sent to the converter for processing

Example Bytecode

The application loads with an example bytecode demonstrating a simple contract. Try decompiling it to see how the tool works.

Technical Details

• Dependencies:

  • Web3.js (loaded via CDN) for Ethereum blockchain interaction
  • Mermaid.js (loaded via ES module) for flowchart visualization
  • No build process or Node.js dependencies required - pure client-side web app

• Browser Support:

  • Modern browsers with ES6 module support
  • Tested in Chrome, Firefox, Safari, and Edge

• Security Note:

  • All processing happens client-side - no bytecode is sent to external servers unless you explicitly use the external converter or blockchain lookup features
  • Infura URL in the code requires your own project ID for blockchain lookups

Recent Fixes

• Mermaid Initialization: Fixed conflicting Mermaid initializations that were causing rendering errors
• Git Repository Safety: Added repository to Git's safe.directory list to resolve ownership warnings
• Stage Highlighting: Corrected Mermaid node highlighting logic for proper workflow visualization

Customization

• Modify mermaid.css to change the visual appearance of the flowchart and UI
• Update the opcode definitions in index.html if needed (though they follow Ethereum Yellow Paper standards)
• Adjust the Mermaid flowchart in index.html (lines 115-126) to represent different contract patterns

Development

This is a static web application - no special development setup is required. Simply edit the files and refresh your browser to see changes.

For VS Code users, the .vscode directory contains recommended settings.

License

MIT License - feel free to use, modify, and distribute this tool as needed.

Acknowledgments

• Based on Ethereum Yellow Paper opcode definitions
• Uses Mermaid.js for diagram rendering
• Web3.js for Ethereum blockchain interaction