I am starting a series of writeup of the Ethernaut challenges, this project have been initiated by OpenZeppelin team to teach basic knowledge of smart contracts auditing.

The challenges will be resolved with Foundry, the client, if needed will be written in Golang and the smart contracts will be written in Solidity.

The current list of challenges are:

0. Hello Ethernaut
1. Fallback
2. Fallout
3. CoinFlip
4. Telephone
5. Token
6. Delegation
7. Force
8. Vault
9. King
10. Re-Entrancy
11. Elevator
12. Privacy
13. GatekeeperOne
14. GatekeeperTwo
15. NaughtCoin
16. Preservation
17. Recovery
18. Magic Number
19. AlienCodex
20. Denial
21. Shop
22. Dex
23. Dex Two
24. PuzzleWallet
25. Motorbike

The folder structure of each challenge is:

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ethernautWritup
├── about
│   ├── index.md
├── ethernautChallenges
│   ├── 0-HelloEthernaut
│   │   ├── 0-HelloEthernaut.go
│   ├──1-Fallback
│   |   └── 1-Fallback.go
│   ├──2-Fallout
│   |   └── 2-Fallout.go
│   ├──...
│
└── contracts
    ├── 0-HelloEthernaut.sol # If provided
    └── HelloEthernaut.abi

When a smart contract is needed to resolve the challenge, foundry will be used. The environment can be created with

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forge init ethernaut

It will look like this

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ethernaut
├── lib
│   ├── ...
├── src
│   ├── challengeName.sol # Source of the challenge
│   ├──...
│
├── test
│   ├── challengeName.t.sol # Contract to resolve the challenge
│   └── ...
│
└── foundry.toml

To convert easily the solidity code to go code the solidity2go.sh script will be used:

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#!/bin/bash

if [[ $1 -eq "" ]]; then
echo "The name is required"
exit
fi

mkdir ../$1
./solc --abi $1.sol -o . --overwrite  @openzeppelin/=$(pwd)/node_modules/@openzeppelin/
pkgName=$(cat $1.sol| grep contract | cut -d" " -f 2)
./abigen --abi=./$pkgName.abi --pkg=$pkgName --out=../$1/$1.go

In the same folder, the node_modules should be installed

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npm i @openzeppelin/contracts@3.4

For example for the challenge 1-Fallback, the script will be called like this:

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./solidity2go.sh 1-Fallback

I’m going to learn a lot during this series, so the solutions written in Go or Solidity will probably get better and better as I go through the challenges.