Paradigm CTF 2021

Installing

Prerequisites

• Docker
• solc-select
• mpwn
• Python 3

Configuration

You'll need to set the following environment variables:

• ETH_RPC_URL to a valid Ethereum JSON-RPC endpoint
• PYTHONPATH to point to mpwn

You'll also need to manually install the following:

• pip install ecdsa pysha3 web3

Usage

Build everything

./build.sh

Run a challenge

Running a challenge will open a port which users will nc to. For Ethereum related challenges, an additional port must be supplied so that users can connect to the Ethereum node (which forks from mainnet state)

./run.sh babycrypto 31337

On another terminal:

nc localhost 31337

For ETH challenges:

./run.sh bank 31337 8545

When prompted for the hashcash PoW, use the default secret secret:

$ nc localhost 31337
1 - launch new instance
2 - get flag
action? 1
hashcash -mb24 gdrfjbxs = ? secret

your private blockchain has been deployed
it will automatically terminate in 30 minutes
here's some useful information

Running the autosolver

./solve.sh

Add a new challenge

1. Copy one of the existing challenge directories and rename it to your challenge's name
2. Edit the info.yaml to add your details
3. Add your contracts under the public/contracts directory
4. Add any contracts which are supposed to be private, such as the source code for a rev challenge or a challenge solution under the contracts/private directory
5. Add it to the build script with the dirname and compiler version
6. (Optional) Allow it to be auto-solved:
   1. Do either of the following:
      • Add an private/Exploit.sol file with a constructor(Setup setup) constructor that solves the challenge
      • Add a private/solve.py if it requires additional actions to be executed (e.g. babycrypto, vault)
   2. Then add it to the solve script