ZyXEL Communications nwa series, Руководство пользователя

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NWA/WAC/WAX Series User’s Guide
182
C
HAPTER
16
Certificates
16.1 Overview
The Zyxel Device 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 this Chapter
• The My Certificates screens ( Section 16.2 on page 185 ) generate and export self-signed certificates or
certification requests and import the Zyxel Device’s CA-signed certificates.
• The Trusted Certificates screens ( Section 16.3 on page 192 ) save CA certificates and trusted remote
host certificates to the Zyxel Device. The Zyxel Device trusts any valid certificate that you have
imported as a trusted certificate. It also trusts any valid certificate signed by any of the certificates
that you have imported as a trusted certificate.
16.1.2 What You Need to Know
The following terms and concepts may help as you read this chapter.
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.
These keys work like a handwritten signature (in fact, certificates are often referred to as “digital
signatures”). Only you can write your signature exactly as it should look. When people know what your
signature looks like, they can verify whether something was signed by you, or by someone else. In the
same way, your private key “writes” your digital signature and your public key allows people to verify
whether data was signed by you, or by someone else.
This process works as follows:
1
Tim wants to send a message to Jenny. He needs her to be sure that it comes from him, and that the
message content has not been altered by anyone else along the way. Tim generates a public key pair
(one public key and one private key).
2
Tim keeps the private key and makes the public key openly available. This means that anyone who
receives a message seeming to come from Tim can read it and verify whether it is really from him or not.
3
Tim uses his private key to sign the message and sends it to Jenny.
4
Jenny receives the message and uses Tim’s public key to verify it. Jenny knows that the message is from
Tim, and that although other people may have been able to read the message, no-one can have
altered it (because they cannot re-sign the message with Tim’s private key).