Quiz Entry - updated: 2026.07.14
What are the "2 security requirements, 2 protection mechanisms, 4 principles" framework in cryptography?
Two requirements (confidentiality + data integrity) combined with two mechanism types (symmetric + asymmetric) yield 4 fundamental principles.
* Two goals (confidentiality, integrity) times two key types (symmetric, asymmetric) give the four principles. *
The 2×2 matrix:
| Symmetric (shared key) | Asymmetric (key pair) | |
|---|---|---|
| Confidentiality | Symmetric Encryption | Asymmetric Encryption |
| Data Integrity/Authenticity | MAC | Digital Signature |
The 4 principles:
- Symmetric Encryption — Shared secret key encrypts/decrypts
- Asymmetric Encryption — Public key encrypts, private key decrypts
- MAC (symmetric authentication) — Shared secret key generates/verifies authentication tag
- Digital Signature (asymmetric authentication) — Private key signs, public key verifies
This is the foundational framework of modern cryptography. Every protocol (TLS, SSH, PGP, etc.) is built by combining these 4 principles.
Go deeper:
Public-key cryptography — the asymmetric column (encryption and signatures).