This document discusses several methods of network management and security including public key cryptography, link encryption, DES/AES encryption, and VPN. Public key cryptography uses two different keys for encryption and decryption of messages. Link encryption secures data as it is transmitted between two network points. DES is a older block cipher encryption standard that uses a 56-bit key, while AES is an improved version and current standard that also uses a shared key. VPN allows remote access to a private network by establishing a secure tunnel between devices.

1. How Network
Management Systems Work
● Public key
● VPN
● Link encryption
● DES and AES

2. Public key
● Encryption is process of
transforming information
for secure personal data.
Other person can't read
information that is
encrypted.
● Public key cryptosystem
is one of encryption
method. It use two keys
for encrypt a message
and decrypt it. The two
keys is different.

3. Link encryption
● The link
encryption,and it is an
encryption,and
security process of
data as information.
● It is transmitted in the
network between two
points as a level.

4. DES and AES
● DES is stands for the Data
Encryption Standard. DES
is one of block cipher(a
form of shared secret
encryption). DES is based
on common key
cryptosystem that uses 56-
bit key.
● AES is stands for the
Advanced Encryption
Standard. AES is also
common key cryptosystem.
AES is version of improved
DES's security.

5. VPN
● The Virtual Private
Network is called the
VPN for short.
● VPN is the service for
electronic
communications
company or artifice
which connect up to
LAN.

6. References
● Wikipedia
hap://ja.wikipedia.org/wiki