Solidity Security

Master smart contract security best practices, vulnerability prevention, and secure Solidity development patterns.

When to Use This Skill

• Writing secure smart contracts
• Auditing existing contracts for vulnerabilities
• Implementing secure DeFi protocols
• Preventing reentrancy, overflow, and access control issues
• Optimizing gas usage while maintaining security
• Preparing contracts for professional audits
• Understanding common attack vectors

Detailed patterns and worked examples

Detailed pattern documentation lives in references/details.md. Read that file when the navigation tier above is insufficient.

Testing for Security

// Hardhat test example
const { expect } = require("chai");
const { ethers } = require("hardhat");

describe("Security Tests", function () {
  it("Should prevent reentrancy attack", async function () {
    const [attacker] = await ethers.getSigners();

    const VictimBank = await ethers.getContractFactory("SecureBank");
    const bank = await VictimBank.deploy();

    const Attacker = await ethers.getContractFactory("ReentrancyAttacker");
    const attackerContract = await Attacker.deploy(bank.address);

    // Deposit funds
    await bank.deposit({ value: ethers.utils.parseEther("10") });

    // Attempt reentrancy attack
    await expect(
      attackerContract.attack({ value: ethers.utils.parseEther("1") }),
    ).to.be.revertedWith("ReentrancyGuard: reentrant call");
  });

  it("Should prevent integer overflow", async function () {
    const Token = await ethers.getContractFactory("SecureToken");
    const token = await Token.deploy();

    // Attempt overflow
    await expect(token.transfer(attacker.address, ethers.constants.MaxUint256))
      .to.be.reverted;
  });

  it("Should enforce access control", async function () {
    const [owner, attacker] = await ethers.getSigners();