ZyXEL ZyWALL 5 User Guide - Page 400

Verifying a Certificate

Page 400 highlights

Chapter 20 Certificates The ZyWALL uses certificates based on public-key cryptology to authenticate users attempting to establish a connection. The method used to secure the data that you send through an established connection depends on the type of connection. For example, a VPN tunnel might use the triple DES encryption algorithm. The certification authority uses its private key to sign certificates. Anyone can then use the certification authority's public key to verify the certificates. A certification path is the hierarchy of certification authority certificates that validate a certificate. The ZyWALL does not trust a certificate if any certificate on its path has expired or been revoked. Certification authorities maintain directory servers with databases of valid and revoked certificates. A directory of certificates that have been revoked before the scheduled expiration is called a CRL (Certificate Revocation List). The ZyWALL can check a peer's certificate against a directory server's list of revoked certificates. The framework of servers, software, procedures and policies that handles keys is called PKI (public-key infrastructure). Advantages of Certificates Certificates offer the following benefits. • The ZyWALL only has to store the certificates of the certification authorities that you decide to trust, no matter how many devices you need to authenticate. • Key distribution is simple and very secure since you can freely distribute public keys and you never need to transmit private keys. Self-signed Certificates You can have the ZyWALL act as a certification authority and sign its own certificates. 20.1.3 Verifying a Certificate Before you import a trusted CA or trusted remote host certificate into the ZyWALL, you should verify that you have the actual certificate. This is especially true of trusted CA certificates since the ZyWALL also trusts any valid certificate signed by any of the imported trusted CA certificates. You can use a certificate's fingerprint to verify it. A certificate's fingerprint is a message digest calculated using the MD5 or SHA1 algorithms. The following procedure describes how to check a certificate's fingerprint to verify that you have the actual certificate. 1 Browse to where you have the certificate saved on your computer. 2 Make sure that the certificate has a ".cer" or ".crt" file name extension. Figure 232 Certificates on Your Computer 400 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. ZyWALL 5/35/70 Series User's Guide

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Chapter 20 Certificates
ZyWALL 5/35/70 Series User’s Guide
400
The ZyWALL uses certificates based on public-key cryptology to authenticate users
attempting to establish a connection. The method used to secure the data that you send through
an established connection depends on the type of connection. For example, a VPN tunnel
might use the triple DES encryption algorithm.
The certification authority uses its private key to sign certificates. Anyone can then use the
certification authority’s public key to verify the certificates.
A certification path is the hierarchy of certification authority certificates that validate a
certificate. The ZyWALL does not trust a certificate if any certificate on its path has expired or
been revoked.
Certification authorities maintain directory servers with databases of valid and revoked
certificates. A directory of certificates that have been revoked before the scheduled expiration
is called a CRL (Certificate Revocation List). The ZyWALL can check a peer’s certificate
against a directory server’s list of revoked certificates. The framework of servers, software,
procedures and policies that handles keys is called PKI (public-key infrastructure).
Advantages of Certificates
Certificates offer the following benefits.
The ZyWALL only has to store the certificates of the certification authorities that you
decide to trust, no matter how many devices you need to authenticate.
Key distribution is simple and very secure since you can freely distribute public keys and
you never need to transmit private keys.
Self-signed Certificates
You can have the ZyWALL act as a certification authority and sign its own certificates.
20.1.3
Verifying a Certificate
Before you import a trusted CA or trusted remote host certificate into the ZyWALL, you
should verify that you have the actual certificate. This is especially true of trusted CA
certificates since the ZyWALL also trusts any valid certificate signed by any of the imported
trusted CA certificates.
You can use a certificate’s fingerprint to verify it. A certificate’s fingerprint is a message
digest calculated using the MD5 or SHA1 algorithms. The following procedure describes how
to check a certificate’s fingerprint to verify that you have the actual certificate.
1
Browse to where you have the certificate saved on your computer.
2
Make sure that the certificate has a “.cer” or “.crt” file name extension.
Figure 232
Certificates on Your Computer
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.