7 reasons to shorten SSL certificate validity periods

All certificates expire, by design. Forcing certificate renewal on a regular cadence strengthens security for any PKI implementation. In particular, publicly trusted SSL/TLS certificates have seen multiple reductions in validity periods in the recent past, with more expected in the foreseeable future. Handled incorrectly, this reduction in maximum term can result in increased workload and risk of outage or breach. Nonetheless, the reasons to keep certificate lifespans short are very compelling.

Despite the risks of expiration, certificate validity periods remain crucial, as they help address evolving cybersecurity vulnerabilities. By requiring organizations to renew and deploy certificates with updated security enhancements, they limit the window of opportunity for attackers to exploit potential weaknesses.

A growing emphasis on shorter certificate lifespans reflects a broader industry commitment to enhancing cybersecurity and staying ahead of emerging threats. This is evident in recent proposals, with Google proposing 90-day lifespans and Apple aiming for just 47 days. These tech giants are far from alone in this push—experts at Sectigo are also enthusiastic about this shift, recognizing its potential to enhance security, streamline efficiency, and promote crypto agility.

Speaking to the urgent need for shorter validity periods, Sectigo's Jason Soroko explains, "It's just crazy to think about how long our certificate lifespans are right now. It's not how short they are, it's how incredibly long they still are at this moment." The current 398 day maximum lifespans won't always remain that long, however, so it's important for enterprises to prepare for the inevitable: brief validity periods and frequent renewals.

Below, we explore seven reasons why shorter certificate validity periods are beneficial:

1. Reducing risks from private key compromise
   
2. Addressing misissuance and revocation issues
   
3. Ensuring alignment of certificate ownership and domain control
   
4. Promoting cryptographic agility
   
5. Addressing the limitations of existing revocation methods (like OCSP)
   
6. Mitigating the problem with CAs failing to do revocation
   
7. Encouraging automation

Private key compromise

SSL certificates contain public and private keys, with the public key used to encrypt data and secure communications. The private key can decrypt this information but must be kept strictly confidential. Should the private key fall into the wrong hands, man-in-the-middle attacks and data breaches could be difficult to avoid.

Private key compromise is a huge risk, to the point that CAs advise revoking certificates as soon as private keys are exposed. Historically, certificates often had validity periods of 5 or even 10 years, leaving them vulnerable to exploitation for far too long. Modern practices now prioritize shorter lifespans to minimize these risks. In the worst-case scenario, Sectigo's Tim Callan explains, "we want that compromise to exist for as little time as we possibly can." This is best accomplished through even shorter validity periods, which limit the window of time in which a compromised private key can be exploited.

The CA/Browser Forum emphasizes the importance of private key security by requiring CAs to revoke compromised certificates within 24 hours of detection, further highlighting the critical nature of this issue.

Misissuance and revocation

Certificate misissuance can take many forms, such as certificates containing incorrect information, improper morphology, or other flaws that compromise their security. As Tim Callan explains, these issues can render certificates "less secure or less compatible" than desired, creating potential vulnerabilities in the ecosystem.

Ideally, misissuance will be quickly discovered and addressed — but this doesn't always happen. When such issues remain unnoticed, short validity periods provide an extra layer of security by ensuring improperly issued certificates are cycled out more quickly.

Alignment of certificate ownership and domain control

As a critical component of the digital certificate issuance process, domain control validation (DCV) verifies that the organizations requesting SSL/TLS certificates actually own the domain names associated with those certificates. However, as Tim Callan highlights, the current DCV process has significant gaps. In some cases, certificates can remain valid for extended periods without revalidating domain ownership, potentially leaving vulnerabilities unaddressed.

For example, under existing guidelines, DCV reuse periods can extend up to 398 days — the same as the maximum certificate validity period. In theory, a domain could go over two years without undergoing a fresh DCV. This misalignment of certificate ownership and domain control creates risks that shorter certificate lifespans could help mitigate by reducing the window of time in which unchecked domains remain associated with active certificates. As Callan notes, even today’s one-year certificates can seem excessively long, underscoring the need for ongoing efforts to tighten certificate validity periods.

Cryptographic agility

Crypto agility is increasingly vital in today's rapidly changing digital landscape, where new technologies, cryptographic algorithms, and security challenges demand continuous adaptation. This agility will be even more important with the potential for cryptographic algorithm deprecation increasing as the post-quantum cryptography era approaches. At this point, IT professionals can no longer expect to rely on the same cryptographic strategies throughout their careers.

Shorter certificate lifespans foster crypto agility by accelerating the adoption of stronger algorithms and ensure compliance with evolving security standards. For instance, the deprecation of SHA-1 occurred during a time when certificate lifespans were as long as three years, significantly delaying the transition to more secure cryptographic methods. In the post-quantum era, where algorithmic lifespans are uncertain, shorter certificates can help mitigate delays in adopting advanced solutions.

By contrast, longer lifespans are problematic because, simply put, they encourage complacency. Not all businesses and enterprises will proactively adopt improved cryptographic standards or security practices until anticipated expirations force them to seek stronger certificates via renewal.

Existing revocation methods (OCSP) aren’t perfect

The Online Certificate Status Protocol (OCSP) aims to determine the revocation status of SSL/TLS certificates, which is supposed to provide a more reliable method for detecting and addressing compromised certificates. Unfortunately, OCSP is far from perfect. In fact, Tim Callan compares this strategy to a "seatbelt that breaks when you get in a car accident." He adds that OCSP is "fundamentally defeatable," as it can easily function as a single point of failure. Should the OCSP server become overloaded or otherwise unavailable, clients may be inclined to accept certificates regardless of their status. Additionally, OCSP has a privacy problem by allowing browser tracking as explained in episode 272 of the Root Causes podcast.

These issues become less urgent as shorter certificate lifespans provide a reliable stop-gap, effectively mitigating these challenges by reducing reliance on revocation mechanisms altogether.

CAs failing to do revocation

Beyond issuance, certificate revocation represents one of the most crucial responsibilities of modern CAs, yet it is often mishandled. Some CAs fail to revoke compromised certificates promptly, sometimes due to a reluctance to inconvenience their subscribers. This issue has been a recurring problem in the industry, contributing to trust challenges and underscoring the need for better solutions.

Shorter certificate lifespans offer a practical solution by reducing reliance on flawed revocation practices. As Tim Callan notes, if a certificate has a maximum lifespan of just 47 days, it inherently limits the time a compromised certificate can remain active, even if revocation processes are delayed or fail entirely.

Encouraging automation

Shorter lifespans may initially seem like a hindrance to organizations reliant on outdated manual certificate renewal processes, but they also serve as a powerful catalyst for adopting automated solutions. Automation expedites certificate renewal and also brings greater reliability to this process — with automated solutions in place, there's no need to manually track expiration dates or to worry about missed renewals.

Despite these advantages, many organizations have been slow to adopt automated solutions.

This reluctance may stem from a simple (but problematic) resistance to change, with organizations potentially justifying their use of manual methods because they appear to be keeping up with certificate needs, currently. However, as certificate lifespans shorten, this complacency becomes unsustainable. Shorter lifespans create a tipping point where organizations recognize that automation is no longer optional, driving broader adoption of these solutions.

This shift towards automation is a key motivation behind efforts from Apple and Chrome to reduce certificate validity periods.

Challenges and considerations

Shorter validity periods may be necessary, but they could also present major challenges for organizations still relying on manual processes. Increased administrative overhead is to be expected, and the heightened frequency of renewals significantly raises the risk of human error, which could result in certificate outages and disruptions.

Automation can help address these issues, but a proactive approach is essential; this transition takes time and will be easier to navigate before, not after, certificate lifespans shrink.

Embracing shorter certificate lifespans for enhanced security

Shorter certificate lifespans are on the way — and these should not be dreaded, but rather, embraced as an opportunity for improving cybersecurity and compliance. Automated solutions can make this transition a lot easier while helping enterprises maintain maximum visibility and control.

Ready to make this transition? Look to Sectigo Certificate Manager (SCM) for streamlined certificate lifecycle management. Offering complete visibility via a purpose-built, cloud-native platform, SCM optimizes essential CLM processes like discovery, issuance, deployment, revocation, and renewal. Prepare for shrinking certificate lifespans and leverage the power of automation.

Want to learn more? Get in touch to book a demo of Sectigo Certificate Manager!

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