What is public/asymmetric key cryptography?
Public key (asymmetric) cryptography is a system based on pairs of keys called public key and private key. The public key is published while the private key is kept secret with the owner. The need for a sender and a receiver to share a secret key and trust some communications channel is eliminated. This concept was introduced in 1976 by Whitfield Diffie and Martin Hellman. Example: In order to get around the problem introduced in the above example of symmetric key cryptography, a new kind of lock must be created which requires two keys to operate, say A and B. If A is used to lock, B must be used to unlock, and vice versa – this is known as an asymmetric key system. To send a gift to a distant friend, first request your friend’s (empty) strongbox, equipped with this new lock and one of his/her keys. We will call this the public key, to differentiate from the other (private) key that never leaves him/her. Put your gift in her box and lock it with his/her public key. Send him/her the box
