Lesson 5: Cryptography Concepts
Week of Tue, Oct 13 · lesson closes Mon, Oct 19
Take Meerk's quiz for Lesson 5
This lesson's items
Exact due times are in Canvas.
Watch — Professor Messer
Watch — Professor Messer: Cryptography (SY0-701)
Free, independent educational resource. Not affiliated with or endorsed by CompTIA. Watch, then read the notes below.
Know these cold
- Symmetric encryption: same key for encrypt/decrypt — fast; AES-256 is the gold standard. Key distribution is the challenge.
- Asymmetric encryption: public key encrypts, private key decrypts — slower; solves key distribution. RSA (prime factorization), ECC (elliptic curves, smaller keys).
- Hashing: one-way digest — SHA-256 (256-bit), SHA-3, BLAKE2. MD5 (broken, collision attacks). Salting prevents rainbow table attacks on stored passwords.
Meerk's quiz — open the Lesson 5 gate
10 questions, no time limit. 85% on your first attempt in a 24-hour window opens the gate. Retakes inside the window are practice — they help you learn, they don't count. Work alone; the point is to know it, not to have seen it.
Dinner Table Question
Ask at home: If hashing is one-way and cannot be reversed, how do hackers still crack hashed passwords?
En español: Si el hashing es unidireccional y no se puede revertir, ¿cómo siguen los hackers rompiendo contraseñas con hash?