Stage 3 beginner Free
Crypto basics
Tell encoding, hashing and encryption apart, verify files and signatures, and check a website's certificate.
Runs in your browser. Nothing to install — the lesson and a real Linux computer open side by side.
Start Stage 3 →Lesson steps
- Welcome
- Three different things
- Check a download
- Encrypt with a password
- Strong lock, weak key
- Public and private keys
- Send a private note
- Signatures
- Is this the real site?
- Stage complete
What this stage is
Use real OpenSSL commands in a Linux computer that runs inside your browser. The practice files, passwords and websites are synthetic and stay inside the lab.
This stage follows Linux Fundamentals and Networking Basics. It builds a foundation for HTTPS, signatures and password storage in later stages.
By the end you'll be able to
- explain the difference between encoding, hashing and encryption
- check a download against a trusted checksum
- encrypt and decrypt with a shared password, and understand why a weak password still matters
- use a public key to receive a message and verify a digital signature
- inspect a website certificate and reject a wrong name, untrusted issuer or expired certificate
- verify a signed update before decrypting its notes
Learn more (external)
- OpenSSL documentation
- MDN — What is a Certificate Authority?
- NIST — Secure Hash Standard — The standard defining SHA-256 and other SHA-2 hashes.