EVM puzzles

A collection of EVM puzzles. Each puzzle consists on sending a successful transaction to a contract. The bytecode of the contract is provided, and you need to fill the transaction data that won't revert the execution.

How to play

Clone this repository and install its dependencies (npm install or yarn). Then run:

npx hardhat play

And the game will start.

In some puzzles you only need to provide the value that will be sent to the contract, in others the calldata, and in others both values.

You can use evm.codes's reference and playground to work through this.

Solutions

1. You must send a value to the contract such that the first byte of the SHA3 hash of the value is 0xa8
2. The first jump is to the line CALLVALUE ** CALLDATASIZE. You want this to be 64. The next jump is PC + CALLDATASIZE = 65 + CALLDATASIZE. You want this to equal 71. CALLVALUE = 2 and CALLDATASIZE = 6 will solve this
3. Execution succeeds if the RETURNDATASIZE of the newly created contract is 10 bytes. Thus you will pass this level if you pass in creation bytecode that deploys a contract that returns 10 bytes. Example: 0x6005600c60003960056000F3600a6000F3.
4. This puzzle delegatecalls the deployed contract and then checks its storage. The only way to pass this level is if the deployed contract sets the value in storage slot 5 to 0xaa. Here is an example solution contract: 0x6006600c60003960066000F360aa60055500
5. The puzzles executes a CREATE instruction using the calldata, sending along it's entire balance with it. It then expects the balance of the called contract to have half the balance that was sent. To solve this puzzle we can create a very basic contract in Solidity, compile it, and then copy over the bytecode

contract Puzzle5 {
    constructor() payable {
        payable(address(0)).transfer(msg.value/2)
    }
}

We'll also need to send at least 2 wei to the puzzle contract. 6. We must choose a call data size such that after the memory expansion we have MSIZE - CALLDATASIZE = 3. Since memory expands in 32 byte chunks we can choose any CALLDATASIZE x where x > 32 (to meet the first constraint) and x % 32 == 29. The smallest choice is x = 61. 7. You have to pass in a call value of 17 to cause a wraparound in the addition. 8. This puzzle simulates a for loop that executes CALLVALUE number of times. After the loop it checks the amount of gas consumed. To match the gas consumed with the expected value you must set CALLVALUE = 4 9. This puzzle code refuses to receive ether. BUT you can FORCE ether into it by using the SELFDESTRUCT opcode in your calldata contract. So that's what we have to do. 10. ???