How to get a TLS (SSL) certificate
Because TLS certificates are based on complex mathematical principles of public-key cryptography, there is a certain, unavoidable level of intricacy to the process. This brief guide aims to make the process of getting your certificate as painless as possible.
Some key details to keep in mind (these may seem obvious, but getting them right is critical):
- You’ll need to decide on the exact (“canonical”) domain name or names of your site. At a minimum, you should procure a dual-name certificate that covers both your bare domain and the “www” subdomain. (Example: example.com and www.example.com)
- There’s a critical piece of information called the private key. It’s essential that it be kept private at all times. That means it should only be moved around through secure transmission methods, never in an email or instant message.
- Other files relating to the TLS process, including the CSR (certificate signing request) and the certificate itself, are public information and are okay to send around by insecure means.
The process, step by step
The TLS (also know as SSL) certification process goes like this. It’s a little odd in that you buy the certificate before you even create the certificate signing request.
- You choose the domain name (such as example.com + www.example.com) that the certificate is to cover.
- You buy a certificate from a CA (certificate authority) like ssls.com.
- You collect the following basic contact information to incorporate into the CSR:
- City or other locality
- State or Province name
- Organization name
- Organizational unit (if any)
- An email address for a technical contact or web manager
- With this information someone having the technical skills (like your web developer or sys admin) generates your server’s private key and CSR.
- You send the CSR to your CA, usually by pasting the text into a web form.
- The CA verifies you.
- The CA sends you your certificate.
- You install the certificate on your server.
Different levels of ID verification (vetting)
Pricing varies depending on how much vetting of the domain owner the CA performs. The more vetting, the more cost. Some Web browsers indicate the level of vetting in the toolbar. For example, quinn.com uses a basic certificate that encrypts the connection and certifies that the domain name matches the certificate. The CA has not fully verified our identity.
Financial institutions tend to use more fully verified certificates. See schwab.com, for example.
Which certificate to buy
At the vendor we’re using for our example, you have the following choices for dual-name certificates:
- True BusinessID
- True BusinessID with EV
From the standpoint of website visitors, the only one with a visual impact built into browsers is the “True BusinessID with EV”. That one will light up the “green bar” in the web browser, as described above. Therefore, you will most likely want either #1 or #4, as there is no compelling reason to choose the ones in between.
Certificates are good for a limited number of years, so there is a periodic renewal/reinstallation/re-verification expense.
If you want to cover a large number of server names in one domain, you can buy a wildcard certificate. Instead of providing a canonical domain name for a particular server, you’ll specify a wildcard, such as *.example.com. This will cover any subdomain of example.com. There are a few restrictions:
- The “*” covers only one level of name. For example, blog.example.com would be covered, but not blog.tech.example.com.
- Wildcard certificates cost quite a bit more, so it is more cost-effective to have separate certificates for a small number of discrete subdomains.
- EV certificates are not available for wildcard domains.
- Certificate Authority. An organization that issues certificates that web browsers recognize as valid.
- See TLS certificate
- Certificate Signing Request. A file containing information that a CA uses to create a TLS certificate.
- Secure Sockets Layer. An old name for an early version of TLS. Commonly used as a synonym for TLS.
- Transport Layer Security. A set of standards for maintaining secure internet connections.
- TLS certificate
- A file that, when combined with the private key on your web server, enables the web server to communicate securely with web browsers.
- Web browser
- Software that displays web sites on computers, tablets, or mobile devices. Examples: Chrome, Firefox, Safari, and Internet Explorer.
- Web server
- A computer that provides a web site on the internet.