Internal Or External CA- The Best Bet For Your Organization?

Public Key Infrastructure (PKI) is widely used by organizations to secure communications among servers and clients using digital certificates and certificate authorities (CA). Certificates are a combination of cryptographic keys which encrypt user information stored within them.

For certificates to be valid, they need to be signed by the certificate authority. Organizations can use pre-built external CAs, which are trusted by the public, or set up an internal certificate authority, which gives admins full control over implementation and certificate management.

Choosing which CA is right for your organization is challenging because there’s much to consider. We break down the difference between internal and external CAs and which would be a better fit.

What Is an Internal Certificate Authority?

An internal certificate authority, also called a private CA, is a certificate authority designed for internal use — issuing and managing certificates within an organization’s own network rather than for the general public. Internal CAs are commonly used for device authentication for Wi-Fi and VPN.

Internal CAs tend to be used in more secure applications than external CAs because the trust relationships can be tightly controlled by a single organization. However, that also means they’re harder to trust than a publicly available CA, and can’t be used for generic applications such as Email and Web SSL.

Advantages of Internal CAs

The biggest draw for internal CAs is that admins can customize and configure them to fit perfectly into their environments instead of buying them from a public CA. With an internal CA, organizations don’t have to pay for every SSL certificate used, which can be expensive as many organizations deal with hundreds of thousands of certificates

If you have a Microsoft environment, internal CAs can integrate with Active Directory (AD), which has its own certificate management method, Active Directory Certificate Services (AD CS). This is an appealing option for Windows environments because they can provision certificates configured with group policies.

Security standards are better with internal CAs not because they’re inherently more secure than external CAs, but because there are fewer opportunities for outside threats to infiltrate the network. If an external CA is compromised, that could affect every organization that buys third-party certificates.

Disadvantages of Internal CAs

The fact that the admin has full control over how to configure an internal CA is both a blessing and a curse. If you know what you’re doing and what you need, it’s relatively easy to set up an internal CA.

However, if you’re not a PKI expert, it can be more difficult than using an external CA. No one is going to hold your hand during the configuration process, and it could take weeks or even months to fully configure an internal CA, unless you used a Managed PKI solution.

Running an internal CA is a significant financial commitment, so internal CAs were historically used by large companies that employ thousands of people. Fortunately, with the advent of Cloud Managed PKIs, the cost of an Internal CA has come down to just a few dollars a device.

What Is an External CA?

An external CA is a publicly trusted CA that issues certificates to organizations for a fee. Any CA that you use that is not associated with your company is an external CA. External CAs are often used because they’ve established trust with the public at large, though they come with some downsides.

Advantages of External CAs

One of the biggest advantages of external CAs over internal CAs is how much easier they are to implement and manage. Certificates issued by external CAs are much simpler to deal with because they are already validated by most web servers and clients. Admins are relieved from the extra step of getting the majority of the public to trust their certificates.

The onus of setting up a PKI and updating systems is taken away from the IT department. Public CAs work around the clock to make sure their roots are configured for the latest browsers and applications, so their certificates are immediately trusted. That’s work handled by the external CA management team, not the network admins.

External CAs are perfect for small-to-medium businesses that only need a handful of certificates. It’s much easier and cheaper to pay as you go rather than setting up a PKI and creating certificates on your own. However, if you’re a large organization with thousands of employees and clients, an Internal CA might be your best bet.

Disadvantages of External CAs

External CAs are easier to implement than internal CAs, but they are also less flexible in terms of certificate issuance and management. Integration between an external CA and your infrastructure is much more limited than configuring your own internal CA.

External CAs are also less scalable than internal CAs. With an external CA, you will have to purchase each certificate individually. This isn’t much of a problem if you only need a few certificates for specific purposes. However, if you are a large company or your organization grows faster than you anticipated, suddenly you’re spending a lot of money on thousands of certificates.

Internal Certificate Authority Use Cases

Organizations deploy an internal certificate authority across a range of security use cases where centralized certificate control is essential:

• Wi-Fi 802.1X device authentication: Internal CAs issue the client certificates that authenticate devices to the network via 802.1X authentication, eliminating reliance on passwords.
• VPN client certificates: Internal CAs provision certificates that verify user and device identity before granting VPN access, replacing less secure credential-based methods.
• Email signing (S/MIME): Organizations use certificates from an internal CA to digitally sign and encrypt email, ensuring message integrity and sender authenticity inside the enterprise.
• Internal web servers and intranets: Internal CAs issue TLS certificates for intranet portals and internal web services, enabling HTTPS without purchasing public CA certificates for non-public resources.

Deploying a Managed Internal Certificate Authority with SecureW2

The SecureW2 PKI provides the best of both worlds with a Managed PKI that admins can customize to fit their environment and without the heavy burden of implementing and configuring it yourself.

Skip the coding and hassle. Our state of the art management tool allows you to benefit from having a private CA without the associated inconveniences that come with them.

Create a private internal CA in minutes and manage and customize your CA ensuring all your security needs are met. Our advanced PKI comes with a turnkey suite of Certificate Authority management features so you can customize certificate expiration based on a user’s status and stay ahead of expirations with automated notifications.

SecureW2 also allows you to integrate any SAML/LDAP Identity Provider with your internal CA, making it easy to issue certificates. Create robust policies and issue custom certificate templates based on user groups that already exist in your directory.

Our JoinNow Cloud RADIUS solution performs Identity Lookup with Identity Providers, providing another security measure in those key moments before you know you need to revoke a certificate.

A managed internal certificate authority is necessary for some organizations, but it can be difficult to set up and maintain. SecureW2 offers a full complement of PKI services, including private CA custom-tailored to your needs.

Schedule a demo to see how SecureW2 managed internal certificate authority services work for your organization.

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Frequently Asked Questions

What is an internal certificate authority?

An internal certificate authority is a CA operated by an organization solely for its own use, issuing and managing digital certificates within the organization’s private network and PKI infrastructure. Unlike public CAs, an internal CA is not trusted by default outside the organization, but it gives administrators complete control over certificate issuance policies, templates, and lifecycle management.

What is the difference between an internal CA and an external CA?

An internal CA is owned and operated by the organization, while an external CA is a third-party provider whose certificates are publicly trusted by browsers and operating systems. Internal CAs offer greater flexibility and are more cost-effective at scale, but require IT resources to configure and maintain. External CAs are easier to deploy and immediately trusted, but each certificate carries an individual cost and customization options are limited.

When should an organization use an internal certificate authority?

An organization should use an internal certificate authority when it needs to issue large volumes of certificates, requires tight control over certificate policies and templates, or operates use cases such as Wi-Fi 802.1X authentication, VPN access, S/MIME email signing, or internal HTTPS services. Internal CAs are also the right choice when certificates need to be tied directly to directory groups or device enrollment workflows.

What is a managed internal CA?

A managed internal CA is a PKI-as-a-Service offering where a third-party provider (such as SecureW2) hosts and operates the internal CA infrastructure on behalf of the organization. The organization retains full control over certificate policies and issuance while offloading the setup, maintenance, and operational burden to the provider. This model lowers the cost and complexity of running a private CA compared to a fully self-hosted deployment.

How does an internal certificate authority work with Active Directory?

An internal CA can integrate directly with Active Directory (AD) through Active Directory Certificate Services (AD CS), enabling certificate issuance based on group policies. This allows Windows environments to automatically provision certificates to users and devices based on their AD group membership, streamlining certificate enrollment and ensuring consistent policy enforcement across the organization.