Symmetrical and Asymmetrical encryption

Symmetrical encryption is also referred to as secret key encryption, shared key, private key, single key and even session key.

Asymmetrical encryption uses private and public key pairs, only one of which is secret.

A one-way function is easy to compute when being generated but difficult or impossible to compute in reverse.

Quantum encryption, also known as quantum cryptography, uses quantum mechanics to guarantee secure communications. It enables two parties to produce a shared, random-bit string, known only to them, that encrypts and decrypts messages.



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Comparing Symmetric Encryption to a Door Key
Occasionally, security professionals compare symmetric keys to a house key,
and this analogy helps some people understand symmetric encryption a little
better. For example, imagine Marge moves into a new home. She’ll receive a
single key that she can use to lock and unlock her home. Of course, Marge
can’t use this key to unlock her neighbor’s home.

Later, Marge marries Homer, and Homer moves into Marge’s home. Marge
can create a copy of her house key and give it to Homer. Homer can now
use that copy of the key to lock and unlock the house. By sharing copies of
the same key, it doesn’t matter whether Marge or Homer is the one who
locks the door; they can both unlock it.

Similarly, symmetric encryption uses a single key to encrypt and decrypt
data. If a copy of the symmetric key is shared, others who have the key can
also encrypt and decrypt data.