Symmetric vs asymmetric cryptography?
Options
- Symmetric uses a public and private key pair
- Symmetric: one shared key; asymmetric: a key pair (Correct option)
- Asymmetric is always faster than symmetric ciphers
- They are the same thing, with different names
Answer
Symmetric uses one shared key (fast, e.g. AES); asymmetric uses public/private key pairs (key exchange, signatures, e.g. RSA, ECDSA)
Why
Symmetric: the same secret key locks and unlocks (AES). Very fast, but both sides must somehow share the key safely.
Asymmetric: each party has a public key (shared with anyone) and a private key (kept secret). Data encrypted with the public key can only be decrypted with the private key; signing with the private key can be verified with the public key. Slower.
TLS combines them: asymmetric to agree on a key, symmetric for the actual data.
Remember
Symmetric = one shared key. Asymmetric = public + private key.