Types of Encryption

There are two general categories for key-based encryption - symmetric and asymmetric. Symmetric encryption uses a single key to encrypt and decrypt the message. This means the person encrypting the message must give that key to the recipient before they can decrypt it. To use symmetric encryption, the sender encrypts the message and, if the recipient does not already have a key, sends the key and ciphertext separately to the recipient.

The recipient then uses the key to decrypt the message. This method is easy and fast to implement but has weaknesses; for instance, if an attacker intercepts the key, they can also decrypt the messages. Furthermore, single key encryptions tend to be easier for people to crack, which means that the algorithm that is used to encode the message is easier for attackers to understand, enabling them to more easily decode the message.

Asymmetric encryption, also known as Public-Key encryption, uses two different keys - a public key to encrypt the message, and a private key to decrypt it. The public key can only be used to encrypt the message and the private key can only be used to decrypt it. This allows a user to freely distribute his or her public key to people who are likely to want to communicate with him or her without worry of compromise because only someone with the private key can decrypt a message.

To secure information between two users, the sender encrypts the message using the public key of the receiver. The receiver then uses the private key to decrypt the message. Unlike with single or shared keys, in the asymmetric key system only the recipient can decrypt a message; once the sender has encrypted the message he or she cannot decrypt it. The private key is never distributed; therefore an attacker cannot intercept a key that decrypts the message.