ZyXEL Communications ZyWALL5UTM 4.0 User Manual

ZyWALL 5/35/70 Series User’s Guide

357 

Chapter 20 Certificates

Certificates issued by certification authorities have the certification authority’s signature for 
you to check. Self-signed certificates only have the signature of the host itself. This means that 
you must be very careful when deciding to import (and thereby trust) a remote host’s self-
signed certificate. 

A certificate’s fingerprints are message digests calculated using the MD5 or SHA1 algorithms. 
The following procedure describes how to use a certificate’s fingerprint to verify that you have 
the remote host’s actual certificate. 

1 Browse to where you have the remote host’s certificate saved on your computer. 

2 Make sure that the certificate has a “.cer” or “.crt” file name extension.

Figure 169   Remote Host Certificates

3 Double-click the certificate’s icon to open the Certificate window. Click the Details tab 

and scroll down to the Thumbprint Algorithm and Thumbprint fields.

Import

Click Import to open a screen where you can save the certificate of a remote host 

(which you trust) from your computer to the ZyWALL.

Refresh

Click this button to display the current validity status of the certificates.

Table 117   Trusted Remote Hosts (continued)