1-11 Public Key ConfigurationThis chapter includes these sections:z Asymmetric Key Algorithm Overviewz Configuring the Local Asymmetric Key Pairz Configuring the Public Key of a Peerz Displaying and Maintaining Public Keysz Public Key Configuration ExamplesAsymmetric Key Algorithm OverviewBasic Conceptsz Algorithm: A set of transformation rules for encryption and decryption.z Plain text: Information without being encrypted.z Cipher text: Encrypted information.z Key: A string of characters that controls the transformation between plain text and cipher text. Itparticipates in both the encryption and decryption.Key Algorithm TypesAs shown in Figure 1-1, the information in plain text is encrypted by an algorithm with the help of a keybefore being sent. The resulting cipher text is transmitted across the network to the receiver, where it isdecrypted by the same algorithm also with the help of a key to obtain the original plain text.Figure 1-1 Encryption and decryptionThere are two types of key algorithms, based on whether the keys for encryption and decryption are thesame:z Symmetric key algorithm: The keys for encryption and decryption are the same. Commonly usedsymmetric key algorithms include Advanced Encryption Standard (AES) and Data EncryptionStandard (DES).z Asymmetric key algorithm: The keys for encryption and decryption are different, one is the publickey, and the other is the private key. The information encrypted with the public key can only bedecrypted with the corresponding private key, and vice versa. The private key is kept secret whilethe public key may be distributed widely, and the private key cannot be practically derived from thepublic key.
