Symmetric Key Algorithms

You already learned about symmetric key ciphers and the major issue with symmetric keys. Read the section in this article on symmetric key encryptions to learn more about the advantages and disadvantages of symmetric keys. There is more information about symmetric key ciphers in this article that will be covered in more detail later in this unit, but this article will give you a preview of 3DES, IDEA, and AES ciphers. View the flashcard tool as well to better understand and to learn the terms used in cryptography such as plaintext, ciphertext, key, encryption, decryption, countermeasure, symmetric key encryption, and block cipher.

18. Implementations

In this section, you will review implementations to secure communication.

Secure Socket Layer

Secure socket layer (SSL) is a protocol that is used by most websites to obtain confidential information from the user. It uses a combination of asymmetric and symmetric encryption methods to secure links. A sever sends a public asymmetric key to the client. The client uses the received key to encrypt a symmetric session key. The client then returns the ciphertext back to the server which uses the corresponding private key to decrypt the asymmetric encryption and gain the symmetric session key. The client and server can then both use the symmetric key for communications for the rest of the session. One of the most popular examples of SSL is its use in HTTPS, secure HTTP. The video, How SSL works tutorial – with HTTPS example (11:08), provides a tutorial on setting up SSL to provide a secure web connection.