Quiz Entry - updated: 2026.07.14
What three classes of measures ensure confidentiality, and how do symmetric and asymmetric encryption differ?
Encryption, access control, and secure deletion — and encryption itself splits into symmetric (one shared key) and asymmetric (a public/private key pair).
Confidentiality — keeping data readable only to those authorised — is achieved through three complementary measure classes:
- Encryption — render data unreadable without the key.
- Access control — ensure only authorised identities can reach the data at all (authentication + authorisation).
- Secure deletion / disposal — when data is no longer needed, destroy it so it can't be recovered (a proper end-of-life concept, not just "move to trash").
Encryption comes in two forms:
| Symmetric | Asymmetric | |
|---|---|---|
| Keys | One shared secret key | A key pair: public + private |
| How | Same key encrypts and decrypts | Public key encrypts; only the private key decrypts |
| Trade-off | Fast, but the key must be shared securely | Solves key distribution; slower |
Tip: Symmetric = one key both parties must already share. Asymmetric = anyone can lock it with your public key, but only you can open it with your private key.