What are symmetric-key encryption, public-key encryption, digital signature, and digital certificate?
Encryption is the art of scrambling a message before sending it out so that only the intended recipient who knows how to unscramble the data can read the message. In symmetric-key encryption, the sender scrambles (encrypts) the data using a secret key while the recipient can unscramble (decrypt) the data using the same key. The disadvantage of symmetric key encryption is that it depends heavily on a secure channel to send the key to the recipient. Otherwise, if a third party is in possession of the secret key, the encryption becomes useless. This is a catch-22 situation. You want to use encryption because the communication channel is insecure, but you need a secure channel to transmit the key. Another problem is when you communicate with a large number of people (such as email communications), you need to use a different key for each of your correspondents, and therefore, you need to keep a large number of secret keys. The concept of public-key encryption was introduced in 1976 by Whit
