Wildcard certificates have become a popular choice for organizations that need to secure multiple subdomains with a single certificate. However, there is often confusion about whether wildcard certificates need a Subject Alternative Name (SAN). In this article, we will delve into the world of wildcard certificates and SAN to provide clarity on this topic.
What are Wildcard Certificates?
Wildcard certificates are a type of SSL/TLS certificate that allows you to secure multiple subdomains with a single certificate. They are called “wildcard” because they use a wildcard character () to represent multiple subdomains. For example, a wildcard certificate for .example.com would secure shop.example.com, blog.example.com, and any other subdomain of example.com.
Wildcard certificates are convenient and cost-effective, as they eliminate the need to purchase and manage multiple certificates for each subdomain. They are also easier to install and configure, as they only require a single certificate to be installed on the server.
How do Wildcard Certificates Work?
Wildcard certificates work by using a wildcard character (*) in the domain name. When a user visits a subdomain, the browser checks the certificate to ensure it matches the domain name. If the certificate has a wildcard character, the browser will match the subdomain to the wildcard character, allowing the connection to proceed.
For example, if a user visits shop.example.com, the browser will check the certificate for *.example.com. Since the subdomain “shop” matches the wildcard character, the connection will be allowed.
What is a Subject Alternative Name (SAN)?
A Subject Alternative Name (SAN) is an extension of the X.509 certificate standard that allows multiple domain names to be associated with a single certificate. SANs are used to specify additional domain names that the certificate is valid for, beyond the primary domain name specified in the certificate.
SANs are commonly used in two scenarios:
- When a single certificate needs to secure multiple domain names (e.g., example.com and example.net).
- When a single certificate needs to secure multiple subdomains (e.g., shop.example.com and blog.example.com).
Do Wildcard Certificates Need a SAN?
Now, let’s address the question of whether wildcard certificates need a SAN. The answer is no, wildcard certificates do not need a SAN. Since wildcard certificates already allow multiple subdomains to be secured with a single certificate, there is no need to specify additional domain names using a SAN.
In fact, including a SAN in a wildcard certificate can actually cause problems. Some browsers and clients may not recognize the SAN and may instead rely solely on the wildcard character. This can lead to errors and security warnings.
Example of a Wildcard Certificate without a SAN
Here is an example of a wildcard certificate for *.example.com:
| Field | Value |
| — | — |
| Subject | CN=*.example.com |
| Issuer | CN=Example CA, O=Example Inc. |
| Valid From | 2022-01-01 00:00:00 GMT |
| Valid To | 2023-01-01 00:00:00 GMT |
In this example, the certificate is valid for all subdomains of example.com, without the need for a SAN.
Best Practices for Using Wildcard Certificates
While wildcard certificates do not need a SAN, there are some best practices to keep in mind when using them:
- Use a secure private key: Make sure to generate a secure private key for your wildcard certificate, using a secure random number generator.
- Use a trusted certificate authority: Choose a trusted certificate authority (CA) to issue your wildcard certificate, to ensure it is recognized by most browsers and clients.
- Configure your server correctly: Make sure to configure your server to use the wildcard certificate correctly, including setting the correct domain name and subdomains.
- Monitor your certificate: Regularly monitor your wildcard certificate to ensure it is still valid and has not been revoked.
Conclusion
In conclusion, wildcard certificates do not need a SAN. They are designed to secure multiple subdomains with a single certificate, using a wildcard character. While SANs are useful in certain scenarios, they are not necessary for wildcard certificates.
By following best practices and using a secure wildcard certificate, you can ensure the security and integrity of your online presence.
What is a Wildcard Certificate?
A Wildcard Certificate is a type of SSL/TLS certificate that allows you to secure multiple subdomains with a single certificate. It is issued to a domain and its subdomains, using a wildcard character (*) in the domain name. This means that a single Wildcard Certificate can be used to secure multiple subdomains, such as blog.example.com, shop.example.com, and mail.example.com.
Wildcard Certificates are convenient and cost-effective, as they eliminate the need to purchase and manage multiple certificates for each subdomain. They are also easy to install and configure, making them a popular choice for organizations with multiple subdomains.
What is a SAN Certificate?
A SAN (Subject Alternative Name) Certificate is a type of SSL/TLS certificate that allows you to secure multiple domain names with a single certificate. It is issued to a primary domain name and includes additional domain names in the Subject Alternative Name field. This means that a single SAN Certificate can be used to secure multiple domain names, such as example.com, example.net, and example.io.
SAN Certificates are flexible and can be used to secure multiple domain names, including subdomains and top-level domains. They are also useful for organizations that need to secure multiple domain names with different extensions, such as .com, .net, and .io.
What is the difference between a Wildcard Certificate and a SAN Certificate?
The main difference between a Wildcard Certificate and a SAN Certificate is the way they secure multiple domain names. A Wildcard Certificate secures multiple subdomains with a single certificate, using a wildcard character (*) in the domain name. A SAN Certificate, on the other hand, secures multiple domain names, including subdomains and top-level domains, by listing them in the Subject Alternative Name field.
In general, Wildcard Certificates are more suitable for organizations with multiple subdomains, while SAN Certificates are more suitable for organizations with multiple domain names, including subdomains and top-level domains.
Can I use a Wildcard Certificate to secure multiple top-level domains?
No, a Wildcard Certificate cannot be used to secure multiple top-level domains. Wildcard Certificates are limited to securing multiple subdomains of a single top-level domain. If you need to secure multiple top-level domains, you will need to use a SAN Certificate or purchase separate certificates for each top-level domain.
For example, a Wildcard Certificate issued to *.example.com can be used to secure blog.example.com, shop.example.com, and mail.example.com, but it cannot be used to secure example.net or example.io.
Can I use a SAN Certificate to secure multiple subdomains?
Yes, a SAN Certificate can be used to secure multiple subdomains. In fact, SAN Certificates are often used to secure multiple subdomains, as well as multiple top-level domains. When you purchase a SAN Certificate, you can list multiple domain names, including subdomains, in the Subject Alternative Name field.
For example, a SAN Certificate can be used to secure example.com, blog.example.com, shop.example.com, and mail.example.com, as well as example.net and example.io.
What are the requirements for obtaining a Wildcard Certificate?
To obtain a Wildcard Certificate, you will need to meet the following requirements: (1) you must own the domain name and its subdomains, (2) you must have a valid email address associated with the domain name, and (3) you must be able to verify your identity and control over the domain name.
The verification process typically involves receiving an email with a verification code, which you must enter on the certificate authority’s website. Some certificate authorities may also require additional documentation, such as a government-issued ID or a business license.
What are the requirements for obtaining a SAN Certificate?
To obtain a SAN Certificate, you will need to meet the following requirements: (1) you must own the domain names listed in the certificate, (2) you must have a valid email address associated with each domain name, and (3) you must be able to verify your identity and control over each domain name.
The verification process typically involves receiving an email with a verification code for each domain name, which you must enter on the certificate authority’s website. Some certificate authorities may also require additional documentation, such as a government-issued ID or a business license.