What is a digital certificate?

A digital certificate is an important security credential that confirms the authenticity of a website. It functions a lot like a password, with each website receiving its own encrypted key. A third party — known as the certification authority (CA) — verifies that the encrypted key belongs to the proper website. This powerful combination of cryptography and the public key infrastructure (PKI) shapes trust in devices, users, and websites alike.

Many webmasters and business leaders understand that digital certificates are important, but there are still a lot of misconceptions surrounding these security solutions. To that end, we've developed a comprehensive guide that will tell you everything you need to know about digital certificates:

• What are digital certificates used for?
• Why are they important?
• How do digital certificates and digital signatures differ?
• What are the main types of digital certificates?
• How are they issued?

What are digital certificates used for?

Today's internet users are more cautious than ever. They want to know that the websites they visit are reliable, particularly if they intend to purchase products or sign up for services. They depend on digital certificates to let them know whether the websites they frequent are trustworthy.

Digital certificates are, first and foremost, a reliable form of confirmation. Applied to websites, they instantly reveal authentication status. Ideally, they will align with the X.509 standard set in place by the International Telecommunications Union (ITU). This standard relies on the interface description language Abstract Syntax Notation One (ASN.1) to define serialized and deserialized data structures. Under this certificate format, pairs of public and private keys are used to encrypt or decrypt messages.

The typical certificate process begins with an opening act known as a handshake, in which communicating parties exchange a public key and form a secure connection. Private keys are also created, but these are exclusively used on the server side. Together, these public and private keys generate data used to form additional keys for encryption purposes. These short-term keys are known as session keys. Certificates play into this process by providing data files that contain public keys.

Why they’re important

Digital certificates are currently the gold standard of web-based authentication. Benefits associated with digital certificates include:

Cybersecurity

Modern cybersecurity strategies call for a comprehensive, layered approach, in which several solutions work together to provide maximum protection against malicious parties. Digital certificates form an important piece of this puzzle, providing powerful protection against tampering such as man-in-the-middle attacks.

Authentication

Authentication is an important component of cybersecurity, and digital certificates enable it by limiting access to sensitive data. This, in turn, reduces the likelihood that malicious parties will wreak havoc. Certificate-based authentication is a reliable option for verifying identities at a variety of endpoints. Certificates are more versatile than other common forms of authentication, such as biometrics or one-time passwords.

Scalability

Few cybersecurity strategies are as scalable as digital certificates. Because they are relatively easy to issue and reissue, they can be implemented at all stages of business growth. Meanwhile, certificate management solutions ensure that, no matter how many certificates are issued, they remain current and trustworthy through their lifecycles.

User trust

Discerning users want to feel 100 percent confident that the websites they visit are trustworthy. Digital certificates provide an easily recognizable indication of trustworthiness, backed by certificate authorities that are trusted by the browsers that users rely on.

Today's businesses go to great lengths to build rapport with customers, but if authentication is lacking, it will be far more difficult to build a genuine, trusting relationship or convince customers to convert.

Long-term profitability

The qualities highlighted above are all important on their own, but they also coalesce to form an especially compelling advantage: profitability. This can suffer quickly without digital certificates, as visitors are less likely to become customers if they don't implicitly trust your brand and your website.

What's more, a lack of digital certificates could increase the likelihood of eventual data breaches. Not only are these difficult and expensive to resolve, they further diminish trust and further reduce profitability. Digital certificates provide a low-cost means of avoiding these issues, prompting a significant return on investment.

Digital certificate vs digital signature

Digital certificates should not be confused with digital signatures. The latter resembles a physical signature, in that it is entirely unique to the person doing the signing. The digital signature, however, goes a step beyond the strictly physical by assuring the origin of the document in question. As with digital certificates, these signatures rely on public key infrastructure, with public and private pairs of keys working together to encrypt and decrypt messages.

Digital certificates also make the most of PKI, but with the intention of establishing the legitimacy of a particular user or website. These are typically issued by certificate authorities, whereas digital signatures are available from a variety of security agencies or other resources. The digital signature is mainly intended to hold the signer accountable in order to protect the recipient, while the certificate establishes credibility to grant users much-needed reassurance.

Different types

Digital certificates take many forms. These are differentiated by ease of access, strength of security, and many other factors. It's important to understand these distinctions before you proceed, as not all digital certificates provide an equal level of protection.

SSL/TLS certificate

When you picture a 'typical' digital certificate, SSL/TLS certificates are the most likely to come to mind. Secure socket layer (SSL) certificates are especially familiar among the general public. These use a process sometimes referred to as the 'SSL handshake' to verify that web servers have SSL certificates. Once approved, the acronym HTTPS appears, verifying that the website is encrypted via SSL protocol.

A follow-up version known as Transport Layer Security (TLS) expands on this, fixing key SSL vulnerabilities to provide an added level of security.

Several types of SSL/TLS certificates are available, such as:

• Domain validated. Easy to access, domain validated (DV) SSL certificates provide 256-bit encryption, as well as validation of domain ownership. While they offer the most convenience due to how quickly they can be issued, this speed also means that these certificates are more vulnerable than their OV and EV counterparts.
• Organization validated. Offering an extra element of digital trust, organization validation (OV) is an excellent solution for public-facing websites because a Certificate Authority (CA) must verify details about the organization before issuing. It takes more effort to obtain this certificate, but it is somewhat less vulnerable than the aforementioned DV certificate.
• Extended validated. Offering the highest level of online trust, extended validation (EV) is the industry standard for eCommerce websites. Also highly recommended for enterprise websites, this type requires an in-depth vetting process. They cost more and take a bit longer to issue, but they also limit the chances of malicious players obtaining certificates at this level.

Code signing certificate

Similar in many respects to SSL but dedicated to securing software, code signing certificates allow developers to implement digital signatures within code. As with SSL certificates, different levels of validation are available, including an EV option.

As end users download 32-bit or 64-bit executable files, code signing certificates provide a powerful reminder that the code in question was the work of a verified developer — and that no tampering has taken place.

Client certificate

Client certificates establish the identity of individual users (known as clients) when making requests from remote servers. Without the proper certificate, these users will be unable to access or even view protected pages. This concept is often put into play when encrypting emails via S/MIME (Secure/Multipurpose Internet Mail Extensions) certification.

With S/MIME protocol in place, messages can be authenticated via strict encryption processes. Recipients can feel confident that only the approved party has signed the message's contents — and that the email has not been altered or tampered with while in transit.

What is the most common certificate?

As mentioned, SSL certificates are the most immediately recognizable, but no one certificate is preferred in every situation. A lot depends on your specific needs.

Certificate issuance

Once you've determined which digital certificate type fits your unique needs, you'll need to decide where and how you'll get it issued. This process typically follows a simple pattern: find a trusted Certificate Authority (like Sectigo®), complete official requests, provide documentation as needed, and finally, install the certificate. Below, we break down all the key considerations you'll face along the way:

Who can issue a digital certificate?

As we've mentioned, certificate authorities are central to the very concept of the digital certificate. Most web browsers rely on predetermined lists of approved CAs, with strategic verification processes ensuring that the CAs themselves are trustworthy.

A helpful analogy: CAs act a lot like the DMV (Department of Motor Vehicles), but applied to the internet. The DMV is a respected entity that is trusted to discern not only who can safely operate vehicles, but also, to confirm the identities of all those who apply for their license. Likewise, CAs reveal that web pages, users, or devices are who they say they are.

CAs occupy two main categories: public and private. Autonomous by nature, public CAs should never be controlled by the entities that seek certificates. They must meet baseline requirements set by the CA/Browser Forum. Private CAs, however, can be controlled by organizations that issue certificates. In most cases, however, when we reference CAs, we refer to the more respected and trustworthy public CAs which, together, play a crucial role in upholding public key cryptography.

Can you create your own?

The aforementioned private digital certificates are sometimes referred to as self-signed, in that they are created and signed directly by companies or developers, rather than by trusted CAs. These are based around the same PKI that governs public certificates, but with the self-signed version, third-party validation does not enter the picture.

It may be tempting to take on a DIY approach, but remember: the primary value from digital certificates relates to their issuance by trusted third parties. As such, while you could technically create your own certificate, it would not hold the same trustworthiness of public certificates. That being said, many services provide affordable, easy-to-access digital certificates, as well as simple solutions for ensuring that they're properly managed and reissued.

Requirements and steps for issuance

The process of getting a digital certificate will depend, to some extent, on which service and type of certificate you select. Typically, however, you can expect to follow these key steps:

1. Create a Certificate Signing Request (CSR). As a standardized solution for sending public keys to certificate authorities, CSRs are often required prior to obtaining SSL certificates. These contain vital information, such as domain name, organization name, locality, and contact information.
2. Complete Domain Control Validation (DCV). Once the CSR has been submitted, you can proceed with one of several methods for validating your domain. Top options include email, HTTPS hashing, and canonical name records (CNAME) from the Domain Name System (DNS).
3. Provide additional documentation, if required. Depending on the type of certificate you require, further documentation may or may not be needed. With EV certificates, extensive verification will be required to validate physical existence, operational existence, legal names, and assumed names.
4. Install the certificate. Your request was approved and you have received a certificate from the CA. You will now need to actually install the certificate. This process varies between browsers and operating systems but typically involves downloading the certificate and binding it to the website that requires protection.

Reissuance

Digital certificates are not valid forever. Rather, they must be reissued on a regular basis. Keep this in mind when getting them issued in the first place; any steps you take early on will almost certainly need to be repeated later.

Certificate validity periods can vary to some extent but often follow standards set by the CA/Browser Forum. In most cases, SSL/TLS certificates are valid for 398 days, while validity for code signing certificates lasts a full three years. The validity period for SSL/TLS certificates could change, however, and there is currently a great deal of speculation about possible 90-day certificates.

Renewals should occur prior to digital certificates expiring. Wait too long, and you could suffer significant disruptions or even a certificate outage. Thankfully, most CAs provide notification well before certificates expire.

Short validity periods may seem like a nuisance when getting certificates renewed, but they are ultimately advantageous in that they expand the influence of algorithm changes. The shorter the validity window, the more likely it is that the most recent and most secure algorithm will be utilized.

Depending on which CA you use, it may be possible to make the most of the original CSR. Chances are, however, you'll need to create a brand new CSR and once again complete the DCV process.

For businesses that manage multiple certificates, it’s highly recommended to consider a certificate management system, which manages the certificates’ lifecycles and helps to automate the reissuance process.

Secure your site with a digital certificate

Digital certification is a must for modern websites. How you obtain these certificates matters, however, and, without the right CA, certification will only take you so far.

As an industry leader with a strong reputation, Sectigo should be your go-to resource for obtaining digital certificates. We offer a variety of solutions, including several types of SSL/TLS certificates. Our certificate lifecycle management services allow you to secure identities at scale.

A highly reputable Certificate Authority, we are trusted by hundreds of thousands of customers, including over one-third of the Fortune 1000. Passionate about digital security, we are eager to provide the tools and insight needed to keep you and your customers safe.

Ready to get started? Get in touch to learn more.

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