ZyXEL Communications Corporation NWA1121NI Manual De Usuario
Chapter 9 System
NWA1121-NI User’s Guide
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9.9.4 Private-Public Certificates
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.
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.
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).
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.
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).
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).
5
Additionally, Jenny uses her own private key to sign a message and Tim uses Jenny’s public key to
verify the message.
verify the message.
9.9.5 Certification Authorities
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 NWA1121-NI to generate certification requests that
contain identifying information and public keys and then send the certification requests to a
certification authority.
owner. There are commercial certification authorities like CyberTrust or VeriSign and government
certification authorities. You can use the NWA1121-NI to generate certification requests that
contain identifying information and public keys and then send the certification requests to a
certification authority.
9.9.6 Checking the Fingerprint of a Certificate on Your Computer
A certificate’s fingerprints are message digests 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.
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 55
Certificates on Your Computer