Public Key Configuration; Public Key Algorithm Overview; Basic Concepts; Key Algorithm Types - H3C S9500E Series Security Configuration Manual

Public key configuration

Public key algorithm overview

Basic concepts

•
Algorithm: A set of transformation rules for encryption and decryption.
•
Plain text: Information without being encrypted.
•
Cipher text: Encrypted information.
•
Key: A string of characters that controls the transformation between plain text and cipher text.
It is used in both encryption and decryption.

Key algorithm types

The information in plain text is encrypted by the algorithm with the help of a key before being
sent. See Figure 33. The resulting cipher text is transmitted across the network to the receiver,
where it is decrypted by the same algorithm also with the help of a key to obtain the original plain
text.
Figure 33 Encryption and decryption
There are two types of key algorithms, based on whether the keys for encryption and decryption
are the same:
•
Symmetric key algorithm: The keys for encryption and decryption are the same. Commonly
used symmetric key algorithms include Advanced Encryption Standard (AES) and Data
Encryption Standard (DES).
•
Asymmetric key algorithm: The keys for encryption and decryption are different, one is the
public key, and the other is the private key. The information encrypted with the public key can
only be decrypted with the corresponding private key, and vice versa. The private key is kept
secret while the public key may be distributed widely. The private key cannot be practically
derived from the public key.
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