What is public key encryption & decryption?

In public-key encryption, there must be two separate keys for encryption and decryption. The private key is for the owner only, while the public key is available to anyone. One key is required for transmission between the two parties involved in symmetric key cryptography. The same private key is used both to encrypt and decrypt the information.

Who can encrypt a message using a private key?

In an asymmetric key encryption scheme, anyone can encrypt messages using a public key, but only the holder of the paired private key can decrypt such a message. The security of the system depends on the secrecy of the private key, which must not become known to any other.

How does a private key and a public key work?

A private key and public key work in as a pair. The public key (which is specific to person A but everyone knows it [let everyone be B]) can be used to encrypt a message. B then sends the message to A. The private key for person A can then be used to decrypt the message.

What is public-key cryptography (AES)?

If you really want to know the gory details of AES, there's a superb cartoon to guide you along the way. Public-key cryptography involves two related keys for each recipient involved - a private key which is a secret known only by the recipient, and a related public key which is known by all senders.