3Com 4510G - 12 Public Key Configuration; Asymmetric Key Algorithm Overview; Basic Concepts; Key Algorithm Types

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12 Public Key Configuration
When configuring public keys, go to these sections for information you are interested in:
z Asymmetric Key Algorithm Overview
z Configuring the Local Asymmetric Key Pair
z Configuring the Public Key of a Peer
z Displaying and Maintaining Public Keys
z Public Key Configuration Examples
Asymmetric Key Algorithm Overview
Basic Concepts
z 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. It
participates in both the encryption and decryption.
Key Algorithm Types
As shown in Figure 12-1, the information is encrypted before being sent for confidentiality. The cipher
text is transmitted in the network, and then is decrypted by the receiver to obtain the original pain text.
Figure 12-1 Encryption and decryption
There are two types of key algorithms, based on whether the keys for encryption and decryption are
the same:
z Symmetric key algorithm: The same key is used for both encryption and decryption. Commonly
used symmetric key algorithms include Advanced Encryption Standard (AES) and Data
Encryption Standard (DES).
z Asymmetric key algorithm: Both ends have their own key pair, consisting of a private key and a
public key. The private key is kept secret while the public key may be distributed widely. The
information encrypted with the public key/private key can be decrypted only with the
corresponding private key/public key; however, the private key cannot be practically derived from
the public key.