Let’s Encrypt Disables Its OCSP Server: What You Need to Know

LetS Encrypt Shuts Down OCSP, Cites Data Privacy & Infrastructure Concerns

SAN FRANCISCO, CA – August 6, 2025 – Let’s Encrypt, the widely-used certificate authority, has officially decommissioned its Online Certificate Status Protocol (OCSP) service. The move, announced today, marks a notable shift in how certificate revocation is handled and underscores growing concerns about data privacy in the age of ubiquitous HTTPS.

For years, OCSP served as a real-time verification method, allowing browsers and applications to instantly check if a digital certificate was still valid. However, Let’s Encrypt resolute the infrastructure demands of maintaining a reliable, high-volume OCSP service were unsustainable, particularly when weighed against emerging alternatives.”The high infrastructure requirements of OCSP were a factor, but ultimately the data protection problem proved more critical,” explained Let’s Encrypt in a statement. While the organization intentionally avoided logging which IP addresses queried for specific domains, the potential for future legal obligations to collect such data presented an unacceptable risk.

The shift prioritizes the use of certificate Revocation Lists (CRLs). Unlike OCSP, CRLs contain a comprehensive list of revoked certificates, preventing any correlation between user browsing activity and specific domains. Moreover, advancements in CRL technology, such as Mozilla’s CRLite project, are dramatically improving their efficiency and reducing their size, addressing previous concerns about download times and bandwidth usage.

Why This Matters: A Deeper Dive

This change isn’t simply a technical adjustment; it reflects a broader evolution in web security practices.OCSP,while intended to enhance security,inadvertently created privacy vulnerabilities. Each OCSP request revealed information about a user’s browsing habits to the certificate authority.

The move to CRLs, coupled wiht innovations like CRLite, offers a more privacy-respecting approach. CRLite,for example,utilizes a clever compression algorithm to deliver revocation information efficiently,minimizing the performance impact.Looking Ahead: The Future of Certificate Revocation

The decommissioning of Let’s Encrypt’s OCSP service is likely to accelerate the adoption of choice revocation mechanisms. here’s what to expect:

Increased CRL Adoption: Expect wider implementation of crls across browsers and operating systems.
Continued CRLite Development: Mozilla’s CRLite project will likely see increased investment and adoption as a leading solution for efficient CRL distribution.
Focus on Privacy-Enhancing Technologies: The industry will continue to explore and develop new methods for certificate revocation that prioritize user privacy.
Short-Lived Certificates: The trend towards shorter certificate lifespans (already championed by Let’s Encrypt) will further reduce the reliance on real-time revocation checks, as certificates will naturally expire before a revocation becomes necessary.

This transition represents a positive step towards a more secure and privacy-conscious web.By prioritizing data protection and embracing innovative solutions, Let’s Encrypt is setting a new standard for certificate authorities worldwide.

What is the primary benefit of OCSP stapling over direct OCSP checks?

Let’s Encrypt, the widely trusted Certificate Authority (CA), recently disabled its public Online Certificate Status Protocol (OCSP) server. This change impacts how browsers and applications verify the revocation status of SSL/TLS certificates. Hear’s a breakdown of what happened, why it matters, and what steps you should take. This article will cover OCSP revocation checks,SSL certificate validation,and Let’s Encrypt updates.

understanding OCSP and Certificate Revocation

Before diving into the details, let’s quickly recap how certificate revocation works. When an SSL/TLS certificate is compromised or no longer valid, it needs to be revoked before its natural expiration date. This prevents malicious actors from using the certificate for nefarious purposes. There are several methods for checking revocation status:

Certificate Revocation Lists (CRLs): Historically, CAs published CRLs – lists of revoked certificates. However, CRLs can be large and slow to update.

online Certificate Status protocol (OCSP): OCSP provides a real-time method for checking a certificate’s revocation status. A client sends a request to the CA’s OCSP responder, which replies with “good,” “revoked,” or an error.

OCSP Stapling: A performance optimization where the server proactively obtains an OCSP response from the CA and “staples” it to the SSL/TLS handshake. This reduces the load on the CA’s OCSP responders and speeds up connection times. TLS certificate stapling is a key component of modern security.

Why Did Let’s Encrypt Disable Its OCSP Server?

Let’s Encrypt disabled its public OCSP server primarily due to a sustained Distributed Denial-of-Service (DDoS) attack. The attack, which began in February 2024 and escalated over time, overwhelmed the server with malicious traffic, making it unreliable for legitimate users.Maintaining the server under constant attack proved unsustainable and resource-intensive.

The decision wasn’t taken lightly. Let’s Encrypt communicated extensively about the issue and its potential impact. They persistent that the impact on overall security would be minimal, given the widespread adoption of OCSP stapling and choice revocation checking mechanisms.

Impact on Websites and Applications

The disabling of Let’s Encrypt’s OCSP server doesn’t automatically mean yoru website is insecure. Here’s a breakdown of the impact based on how your server is configured:

OCSP Stapling Enabled (Recommended): If your server is correctly configured for OCSP stapling, you likely won’t notice any difference. The server is already providing the OCSP response, bypassing the need to query Let’s Encrypt’s public server.This is the best-case scenario.

OCSP Stapling Disabled, Relying on Direct OCSP Checks: If your server isn’t using OCSP stapling and relies on direct OCSP checks to Let’s Encrypt’s server, users may experience slower connection times or, in some cases, connection errors. Browsers are designed to handle OCSP failures gracefully,often proceeding with a connection but displaying a warning.

Applications with Strict OCSP Validation: Some applications are configured to strictly require a valid OCSP response. These applications may refuse to connect to servers that cannot provide one.

How to Check Your OCSP Stapling Status

Several tools can definitely help you determine if your server is using OCSP stapling:

SSL Labs SSL server Test: https://www.ssllabs.com/ssltest/ – this comprehensive test provides detailed information about your SSL/TLS configuration, including OCSP stapling status.

OpenSSL command: openssl s_client -connect yourdomain.com:443 -status – Look for the line “OCSP response: good” in the output.

Online OCSP Stapling Checkers: Numerous websites offer simple OCSP stapling checks. Search for “OCSP stapling checker” on your preferred search engine.

What Actions Should You Take?

The primary recommendation is to enable OCSP stapling on your web server. Here’s how to do it for common server software:

Apache: Ensure sslstapling on and `SSLStaplingCache shmcb:bytes=1024000:places=100