Why is Symmetric encryption classed as Private Key? I am going for my ethical hacking exam soon and I still can't get my head around why symmetric key encryption is classed as "Private/Secret Key encryption" when symmetric encryption uses the same key and asymmetric encryption (Public Key) uses a public and PRIVATE key.

I just remember by thinking "As symmetric encryption begins with an S that's Secret key and secret key doesn't have a public and secret (private) key because it's weird."

I'm hoping someone will help me think of this in a less confusing way.
Here's an easy way (in my opinion) of keeping it straight: Think of encryption as creating a "secure channel."

Symmetric:

Secret Key K &lt;-----------------------&gt; Secret Key K


Each side has the same shared key. Since they have a shared secret key, messages flow freely between them - they can both encrypt messages to send to one another. The picture is symmetric... the two sides match.

Asymmetric:

Public Key   -----------------------&gt; Private Key


One side has the private key, the other the public key. The public key holder can encrypt messages such that only the private key holder can read them, but the private key holder cannot use his private key to send secure messages to the public key holder (unless they negotiate/exchange some other key(s)). The picture is not symmetric anymore.