ZyXEL 2WG Guida Utente

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ZyWALL 2WG User’s Guide
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 16 
Certificates Screens
16.1  Overview
The ZyWALL can use certificates (also called digital IDs) to authenticate users. Certificates 
are based on public-private key pairs. A certificate contains the certificate owner’s identity and 
public key. Certificates provide a way to exchange public keys for use in authentication.
16.1.1  What You Can Do in the Certificate Screens
• Use the My Certificate screens (see 
) to generate and export 
self-signed certificates or certification requests and import the ZyWALL’s CA-signed 
certificates.
• Use the Trusted CA screens (see 
to save the certificates of 
trusted CAs to the ZyWALL. You can also export the certificates to a computer.
• Use the Trusted Remote Hosts screens (see 
) to import self-
signed certificates from trusted remote hosts.
• Use the Directory Servers screen (see 
) to configure a list of 
addresses of directory servers (that contain lists of valid and revoked certificates).
16.1.2  What You Need to Know About Certificates
A Certification Authority (CA) issues certificates and guarantees the identity of each 
certificate owner. There are commercial certification authorities like CyberTrust or VeriSign 
and government certification authorities. You can use the ZyWALL to generate certification 
requests that contain identifying information and public keys and then send the certification 
requests to a certification authority. 
When using public-key cryptology for authentication, each host has two keys. One key is 
public and can be made openly available; the other key is private and must be kept secure. 
Public-key encryption in general works as follows. 
Tim wants to send a private message to Jenny. Tim generates a public-private key pair. 
What is encrypted with one key can only be decrypted using the other.
Tim keeps the private key and makes the public key openly available.
Tim uses his private key to encrypt the message and sends it to Jenny.
Jenny receives the message and uses Tim’s public key to decrypt it.
Additionally, Jenny uses her own private key to encrypt a message and Tim uses Jenny’s 
public key to decrypt the message.