20.5. Types of Certificates

If you installed your secure server from the RPM package provided in Red Hat Linux , a random key and a test certificate are generated and put into the appropriate directories. Before you begin using your secure server, however, you must generate your own key and obtain a certificate which correctly identifies your server.

You need a key and a certificate to operate your secure server — which means that you can either generate a self-signed certificate or purchase a CA-signed certificate from a CA. What are the differences between the two?

A CA-signed certificate provides two important capabilities for your server:

• Browsers (usually) automatically recognize the certificate and allow a secure connection to be made, without prompting the user.

• When a CA issues a signed certificate, they are guaranteeing the identity of the organization that is providing the webpages to the browser.

If your secure server is being accessed by the public at large, your secure server needs a certificate signed by a CA so that people who visit your website know that the website is owned by the organization who claims to own it. Before signing a certificate, a CA verifies that the organization requesting the certificate was actually who they claimed to be.

Most Web browsers that support SSL have a list of CAs whose certificates they automatically accept. If a browser encounters a certificate whose authorizing CA is not in the list, the browser asks the user to either accept or decline the connection.

You can generate a self-signed certificate for your secure server, but be aware that a self-signed certificate does not provide the same functionality as a CA-signed certificate. A self-signed certificate is not automatically recognized by most Web browsers, and a self-signed certificate does not provide any guarantee concerning the identity of the organization that is providing the website. A CA-signed certificate provides both of these important capabilities for a secure server. If your secure server will be used in a production environment, you probably need a CA-signed certificate.

The process of getting a certificate from a CA is fairly easy. A quick overview is as follows:

1. Create an encryption private and public key pair.

2. Create a certificate request based on the public key. The certificate request contains information about your server and the company hosting it.

3. Send the certificate request, along with documents proving your identity, to a CA. We cannot tell you which certificate authority to choose. Your decision may be based on your past experiences, or on the experiences of your friends or colleagues, or purely on monetary factors.

   Once you have decided upon a CA, you will need to follow the instructions they provide on how to obtain a certificate from them.

4. When the CA is satisfied that you are indeed who you claim to be, they will send you a digital certificate.

5. Install this certificate on your secure server, and begin handling secure transactions.

Whether you are getting a certificate from a CA or generating your own self-signed certificate, the first step is to generate a key. See Section 20.6 Generating a Key for instructions on how to generate a key.