LESSON 10

Secure Coding

Learning objective: Write code with basic security in mind.

Understand

Secure habits prevent most common vulnerabilities.

Key habits: never trust user input, keep secrets out of your code, keep dependencies updated, and handle errors without leaking details. Security is easier when built in from the start rather than added later.

Analogy: Secure coding is like building a house with locks designed in, not bolted on afterwards.

See It in Action

Keep secrets out of source code:

// bad: hard-coded secret
const key = "sk_live_12345";
// good: load from a secure config / env variable
How it works: Hard-coding secrets risks leaking them; loading them from secure configuration keeps them out of your shared code.

Try It Yourself

  1. Check a project for any hard-coded secrets.
  2. Add input validation to one function.
  3. Update one outdated dependency.

Quick Quiz

Which is a secure coding habit?

Challenge

List three secure coding habits and apply one to a project.

Success condition: You applied at least one secure coding habit to real code.