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OCSP stapling

As explained in Real-World Cryptography

OCSP stapling is a TLS technique in which a server supplies a certificate authority's signed certificate-status response during the handshake.

When a certificate is compromised, clients need a way to learn that it should no longer be trusted. OCSP stapling moves the status lookup from each client to the website: the website asks the certificate authority (CA) for a signed certificate-status response and attaches it during the TLS handshake. section 9.3

The basic flow is:

  • The website queries the CA for the status of its certificate. section 9.3
  • The CA returns a signed response indicating the certificate's status. section 9.3
  • The website staples that response to its certificate during the TLS handshake. section 9.3

This approach addresses weaknesses in OCSP: CA services must otherwise remain highly available, requests reveal browsing information to CAs, and browsers may ignore timed-out requests to avoid disrupting users. Revocation remains defense in depth rather than an everyday feature. section 9.3

Figure 9.9 Certificate revocation on the web has had three popular solutions: Certificate Revocation Lists (CRLs), Online Certificate Status Protocol (OCSP), and OCSP stapling.

Compare certificate revocation through CRLs, OCSP, and OCSP stapling. section 9.3

How Real-World Cryptography covers it

How deep it goes
Explains the lookup-and-attach flow and its tradeoffs, without detailing response formats or server configuration.
Examples
Uses the CRL, OCSP, and OCSP stapling comparison, plus compromised certificates such as those exposed by Heartbleed.
What you can do after
Evaluate how stapling reduces OCSP availability, privacy, and timeout problems.
How it connects
Connects certificate revocation with CRLs, OCSP, TLS, certificate authorities, and Certificate Transparency.
Cover of Real-World Cryptography
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Related concepts

This explainer was generated by Manning's knowledge graph from the text of Real-World Cryptography. The section links point to the parts of the book it draws on.