OCSP (Online Certificate Status Protocol) is a protocol used in cybersecurity to check the validity of digital certificates in real time.
OCSP can be used to determine whether a certificate has been revoked by the Certification Authority (CA) that issued it.
How it works
- OCSP enables a client (such as a web browser) to check with a certification authority whether an SSL/TLS is still valid or has been revoked.
- When a user accesses a secure website, the browser sends an OCSP request to the certification authority to check the status of the site's certificate..
- The certification authority responds by indicating whether the certificate is "valid", "revoked" or "unknown".
✔ Advantages over revocation lists (CRLs)
- Provides more up-to-date information on the status of certificates.
- Reduces network traffic by avoiding the need for customers to download large revocation lists.
- Simplifies the verification process for the customer
❌ OCSP drawbacks:
- OCSP server dependency: If the OCSP server is unavailable, the client cannot check the status of the certificate.
- Confidentiality issues: Some people are concerned that using OCSP could reveal information about the websites that users visit.
OCSP Stapling
- Technique that allows the web server to provide the OCSP response directly to the client, improving performance.
- The server "staples" the signed OCSP response to the SSL certificate during the initial exchange.
- Speeds up the HTTPS connection by avoiding a separate request to the certification authority.
Importance of cyber security
- Enables rapid detection of compromised or revoked certificates
- Enhances the security of encrypted communications by checking the validity of certificates in real time
- Plays a crucial role in validating SSL/TLS certificates used to secure websites and online transactions
In summary, OCSP is an essential protocol for maintaining trust in the Public Key Infrastructure (PKI) by enabling rapid and efficient verification of the status of digital certificates.
