EVMole

EVMole is a powerful library that extracts information from Ethereum Virtual Machine (EVM) bytecode, including function selectors, arguments, and state mutability, even for unverified contracts.

Key Features

• Multi-language support: Available as JavaScript, Rust, and Python libraries.
• High accurancy and performance: Outperforms existing tools.
• Broad compatibility: Tested with both Solidity and Vyper compiled contracts.
• Lightweight: Clean codebase with minimal external dependencies.
• Unverified contract analysis: Extracts information even from unverified bytecode.

Usage

JavaScript

API documentation and usage examples (node, vite, webpack, parcel, esbuild)

$ npm i evmole

import { functionSelectors, functionArguments, functionStateMutability } from 'evmole'

const code = '0x6080604052348015600e575f80fd5b50600436106030575f3560e01c80632125b65b146034578063b69ef8a8146044575b5f80fd5b6044603f3660046046565b505050565b005b5f805f606084860312156057575f80fd5b833563ffffffff811681146069575f80fd5b925060208401356001600160a01b03811681146083575f80fd5b915060408401356001600160e01b0381168114609d575f80fd5b80915050925092509256'

console.log(functionSelectors(code));                   // [ '2125b65b', 'b69ef8a8' ]
console.log(functionArguments(code, '2125b65b'));       // 'uint32,address,uint224'
console.log(functionStateMutability(code, '2125b65b')); // 'pure'

Rust

Documentation is available on docs.rs

let code = hex::decode("6080604052348015600e575f80fd5b50600436106030575f3560e01c80632125b65b146034578063b69ef8a8146044575b5f80fd5b6044603f3660046046565b505050565b005b5f805f606084860312156057575f80fd5b833563ffffffff811681146069575f80fd5b925060208401356001600160a01b03811681146083575f80fd5b915060408401356001600160e01b0381168114609d575f80fd5b80915050925092509256").unwrap();

println!("{:x?} | {} | {:?}",
    evmole::function_selectors(&code, 0),
    evmole::function_arguments(&code, &[0x21, 0x25, 0xb6, 0x5b], 0),
    evmole::function_state_mutability(&code, &[0x21, 0x25, 0xb6, 0x5b], 0),
);
// [[21, 25, b6, 5b], [b6, 9e, f8, a8]] | uint32,address,uint224 | Pure

Python

API documentation

$ pip install evmole --upgrade

from evmole import function_selectors, function_arguments, function_state_mutability

code = '0x6080604052348015600e575f80fd5b50600436106030575f3560e01c80632125b65b146034578063b69ef8a8146044575b5f80fd5b6044603f3660046046565b505050565b005b5f805f606084860312156057575f80fd5b833563ffffffff811681146069575f80fd5b925060208401356001600160a01b03811681146083575f80fd5b915060408401356001600160e01b0381168114609d575f80fd5b80915050925092509256'

print(function_selectors(code))                    # ['2125b65b', 'b69ef8a8']
print(function_arguments(code, '2125b65b'))        # uint32,address,uint224
print(function_state_mutability(code, '2125b65b')) # pure

Foundry

Foundy's cast uses the Rust implementation of EVMole

$ cast selectors $(cast code 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2)
0x06fdde03	
0x095ea7b3	address,uint256
0x18160ddd	
0x23b872dd	address,address,uint256
...

$ cast selectors --resolve $(cast code 0xC02aaA39b223FE8D0A0e5C4F27eAD9083C756Cc2)
0x06fdde03	                       	name()
0x095ea7b3	address,uint256        	approve(address,uint256)
0x18160ddd	                       	totalSupply()
0x23b872dd	address,address,uint256	transferFrom(address,address,uint256)
...

Benchmark

function selectors

FP/FN - False Positive/False Negative errors; smaller is better

function arguments

Errors - when at least 1 argument is incorrect: (uint256,string) ≠ (uint256,bytes)

function state mutability

Errors - Results are not equal (treating view and pure as equivalent to nonpayable)

Errors strict - Results are strictly unequal (nonpayable ≠ view). Some ABIs mark pure/view functions as nonpayable, so not all strict errors indicate real issues.

See benchmark/README.md for the methodology and commands to reproduce these results

versions: evmole v0.5.1; whatsabi v0.14.1; sevm v0.7.2; evm-hound-rs v0.1.4; heimdall-rs v0.8.4

^(*): sevm and heimdall-rs are full decompilers, not limited to extracting function selectors

How it works

Short: Executes code with a custom EVM and traces CALLDATA usage.

Long: TODO

License

MIT