EVMole

This library extracts function selectors and arguments from Ethereum Virtual Machine (EVM) bytecode, even for unverified contracts.

JavaScript, Rust and Python implementations
Clean code with zero external dependencies (py & js)
Faster and more accurate than other existing tools
Tested on Solidity and Vyper compiled contracts

Try it online

Usage

JavaScript

$ npm i evmole

import {functionArguments, functionSelectors} from 'evmole'
// Also supported: const e = require('evmole'); e.functionSelectors();

const code = '0x6080604052348015600e575f80fd5b50600436106030575f3560e01c80632125b65b146034578063b69ef8a8146044575b5f80fd5b6044603f3660046046565b505050565b005b5f805f606084860312156057575f80fd5b833563ffffffff811681146069575f80fd5b925060208401356001600160a01b03811681146083575f80fd5b915060408401356001600160e01b0381168114609d575f80fd5b80915050925092509256'
console.log( functionSelectors(code) )
// Output(list): [ '2125b65b', 'b69ef8a8' ]

console.log( functionArguments(code, '2125b65b') )
// Output(str): 'uint32,address,uint224'

Rust

Documentation available on docs.rs

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

println!("{:x?}", evmole::function_selectors(&code, 0));
// Output(Vec<[u8;4]>): [[21, 25, b6, 5b], [b6, 9e, f8, a8]]

println!("{}", evmole::function_arguments(&code, &[0x21, 0x25, 0xb6, 0x5b], 0));
// Output(String): uint32,address,uint224

Python

$ pip install evmole --upgrade

from evmole import function_arguments, function_selectors

code = '0x6080604052348015600e575f80fd5b50600436106030575f3560e01c80632125b65b146034578063b69ef8a8146044575b5f80fd5b6044603f3660046046565b505050565b005b5f805f606084860312156057575f80fd5b833563ffffffff811681146069575f80fd5b925060208401356001600160a01b03811681146083575f80fd5b915060408401356001600160e01b0381168114609d575f80fd5b80915050925092509256'
print( function_selectors(code) )
# Output(list): ['2125b65b', 'b69ef8a8']

print( function_arguments(code, '2125b65b') )
# Output(str): 'uint32,address,uint224'

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)
...

See examples for more

Benchmark

function selectors

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

Dataset		**evmole rs · js · py**	*whatsabi*	*sevm*	*evmhound*	*heimdall*	*smpl*
largest1k _{1000 contracts 24427 functions}	FP _contracts	1 🥈	0 🥇	0 🥇	75	68	95
	FN _contracts	0 🥇	0 🥇	0 🥇	40	103	9
	FP _functions	192 🥈	0 🥇	0 🥇	720	650	749
	FN _functions	0 🥇	0 🥇	0 🥇	191	114	12
	Time	0.6s · 1.6s · 2.1s	2.9s	34.8s^(*)	0.7s	379.5s^(*)	1.7s

random50k _{50000 contracts 1171102 functions}	FP _contracts	1 🥇	43	1	693	519	4136
	FN _contracts	9 🥇	11	85	2903	4669	77
	FP _functions	3 🥇	51	3	10798	545	14652
	FN _functions	10 🥇	12	1759	3538	4943	96
	Time	9.8s · 20.2s · 39s	55.9s	1343s^(*)	11.5s	9881.1s^(*)	47.9s

vyper _{780 contracts 21244 functions}	FP _contracts	0 🥇	30	0	19	780	185
	FN _contracts	0 🥇	780	21	300	780	480
	FP _functions	0 🥇	30	0	19	780	197
	FN _functions	0 🥇	21244	336	8273	21244	12971
	Time	0.4s · 0.8s · 1.2s	2.1s	55.1s^(*)	0.4s	29.1s^(*)	1.1s

function arguments

Errors - when at least 1 argument is incorrect: (uint256,string) != (uint256,bytes); smaller is better

Dataset		**evmole rs · js · py**	*heimdall-rs*	*simple*
largest1k _{1000 contracts 24427 functions}	Errors	14.0%, 3417 🥇	31.1%, 7603	58.3%, 14242
largest1k _{1000 contracts 24427 functions}	Time	1.2s · 12.6s · 30.1s	385.6s^(*)	0.6s

random50k _{50000 contracts 1171102 functions}	Errors	4.5%, 52777 🥇	19.4%, 227078	54.9%, 643213
random50k _{50000 contracts 1171102 functions}	Time	33.7s · 337.7s · 1002.4s	9594.6s^(*)	9.6s

vyper _{780 contracts 21244 functions}	Errors	49.6%, 10544 🥇	100.0%, 21244	56.8%, 12077
vyper _{780 contracts 21244 functions}	Time	0.8s · 8.0s · 16.9s	29.6s^(*)	0.5s

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

versions: evmole v0.3.7; whatsabi v0.12.0; sevm v0.6.18; evm-hound-rs v0.1.4; heimdall-rs v0.8.3

^(*): 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

cdump / evmole