Solidity Puzzles

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Verilog Solutions Inc. https://www.verilog.solutions
Verilog is a full-stack web3 security firm, covering smart contract auditing, 
validator operations, venture investment, and incubation.
Glad to prepare and present the materials for Game Day Remix in DevConnect Amsterdam!

This repo inlcudes three puzzles on smart contract written for Remix Game Day in DevConnect Amsterdam.

Who Are They?

• Puzzle One: Yesterday Once More Time traveled back to 2016, you are the one who hard-fork the Ethereum blockchain.

• Puzzle Two: Safe and Sound No worry, our transfer is secured.

Puzzle 3 is an extra puzzle. Try solve it and write the unit tests yourself!

Play with Remix

1 Load files in remix

• Load files using dGit plugin
  1. Open remix;
  2. Enable dGit plugin in the PLUGIN MANAGER tab;
  3. In dGit > CLONE, PUSH, PULL & REMOTES > CLONE, enter URL to this github repo, then click clone;
  4. Go to FILE EXPLORERS > drag down workspace > select the latest workspace,

2 Play Transactions Recordings

Remix has a cool feature. It can record transactions as a scenario files and all the saved transactions can just be executed in one click.

We record the transactions which includes the contract deployments and attack executions. You can find a series transactions pop up automatically in remix console after playing the transactions.

1. Open a scenario file tx_records/puzzle*.json
2. go to DEPLOY & RUN TRANSACTIONS > Transactions recorded
3. click the play button

3 Explore the Remix Debugger

Inside the remix console, you can see all the transactions. Pick one transaction and click the Debug button.

You can pick the attacking transaction and try debugging it and see what happens exactly inside the exploits.

4 Run Tests & Try Fix bugs

We have prepared two kinds of tests. Try run the tests and fix bugs.

1. solidity tests for remix unit tests (tests/solidity_tests/*)

   You can run it with the SOLIDITY UNIT TESTING plugin (need to activate it first inside the PLUGIN MANAGER).

2. javascripts unit tests which can be run both on remix and hardhat (tests/js_tests/*)

   • run on remix. (make sure you compiled all the contracts first)

     Just right click test file at the file explorer and choose run.

   • run with hardhat locally with yarn hardhat test