Certificate Revocation

In the realm of cybersecurity, trust is paramount. As businesses and individuals increasingly rely on digital communication and transactions, the need for secure and trusted connections has never been more crucial. SSL/TLS certificates play a central role in establishing this trust, encrypting data during transmission, and enabling secure connections. However, what happens when a certificate is compromised or no longer deemed trustworthy? This is where certificate revocation comes into play. We will explore the concept of certificate revocation, its significance, and how it is used to maintain a secure digital environment.

What is Certificate Revocation?

Certificate revocation refers to invalidating an SSL/TLS certificate before its natural expiration date. When a certificate is revoked, it becomes unusable for establishing secure connections, rendering it untrusted by web browsers and other client applications. Revocation is necessary when a certificate’s private key is compromised, the certificate holder’s identity is no longer valid, or there are doubts about the certificate’s integrity.

Certificate revocation is essential to prevent potential security breaches and protect users from unknowingly connecting to websites or services that have lost their trustworthiness. Revoked certificates must be replaced with new, valid certificates to restore secure communication.

When is Certificate Revocation Used?

• Compromised Private Key

  One of the primary reasons for certificate revocation is the compromise of a certificate’s private key. If a private key falls into the wrong hands, malicious actors can use it to decrypt secure communications and even impersonate the legitimate certificate holder. To prevent such scenarios, the certificate authority (CA) revokes the compromised certificate, rendering the private key useless for further communication.

• Change in Certificate Holder’s Status

  Certificates may become invalid if there is a change in the certificate holder’s status. For instance, an employee who had access to a company’s certificate leaves the organization, making the certificate no longer trustworthy. In such cases, the certificate may be revoked to prevent unauthorized access.

• Detection of Fraudulent Certificates

  In some instances, fraudulent certificates may be issued due to mistakes or malicious activities. Certificate authorities actively monitor for any suspicious or unauthorized certificates, and if detected, they are immediately revoked to maintain the integrity of the public key infrastructure.

• Certificate Expiration

  While not a revocation in the traditional sense, certificates are also considered invalid after their expiration date. Certificate revocation lists (CRLs) or online certificate status protocol (OCSP) can indicate whether a certificate is expired or still valid.

How to perform certificate revocation?

To cancel a certificate, you need to pick someone as a certificate manager. This is done by giving a user or a group permission to Issue and Manage Certificates at the issuing CA (Certificate Authority). The CA Administrator, who is a user with the Manage CA permissions, is responsible for this permission setup. Follow these steps to make sure the right permissions are set:

• Open the Certification Authority console from Administrative Tools.
• Right-click on CAName (where CAName is the CA’s name), and choose Properties in the menu.
• In the CAName Properties window, go to the Security tab. Make sure the user’s account or a group they are part of has the Issue and Manage Certificates permission.

With the required permissions, follow these steps to revoke a certificate.

• Open the Certification Authority console from Administrative Tools.
• Expand CAName in the console tree and click on Issued Certificates.
• In the details section, find the certificate you want to revoke. Right-click on it, go to All Tasks and choose Revoke Certificate.
• Pick the appropriate reason code from the options in the Certificate Revocation window and click Yes.
• Check if the recently revoked certificate is now visible in the revoked certificates section.

How to identify revoked certificates?

Public key infrastructure (PKI) provides three ways to determine if a certificate has been revoked:

• Base CRL

  Certificate Revocation List (CRL) contains the serial numbers of certificates revoked by the CA that are signed with the CA’s private key. If you renew a CA’s certificate with a new key pair, the CA maintains two separate CRLs—one for each key pair maintained by the CA. All versions of the Microsoft Windows operating system recognize base CRLs.

• Delta CRL

  This contains only the serial numbers of certificates revoked by the CA since the last base CRL publication. Again, if the CA’s certificate is renewed with a new key pair, separate delta CRLs are maintained for each CA key pair. Delta CRLs allow you to publish revocation information quicker and allow smaller updates to be downloaded by client computers.

• OCSP

  Online Certificate Status Protocol (OCSP) provides a responder service that can either connect directly to a CA database or inspect the base and delta CRLs published by the CA to determine the revocation status of a specific certificate.

Conclusion

Trust and security are fundamental pillars for digital communication and transactions in the ever-evolving cybersecurity landscape. SSL/TLS certificates are vital in establishing this trust, ensuring data encryption, and enabling secure connections between users and servers. However, certificate revocation becomes a critical process in the face of potential compromise or loss of trustworthiness.

Certificate revocation invalidates SSL/TLS certificates before their natural expiration date. When a certificate is revoked, it becomes unfit for establishing secure connections, rendering it untrusted by web browsers and other client applications. The reasons for certificate revocation include the compromise of a certificate’s private key, changes in the certificate holder’s status, detection of fraudulent certificates, and certificate expiration.

By promptly revoking compromised or untrustworthy certificates, certificate authorities and organizations can prevent potential security breaches and protect users from connecting to insecure websites or services. Revoked certificates must be replaced with new, valid certificates to restore secure communication.

How can Encryption Consulting help?

Encryption Consulting provides a specialized Certificate Lifecycle management solution CertSecure Manager. From discovery and inventory to issuance, deployment, renewal, revocation, and reporting. CertSecure provides an all-encompassing solution. Intelligent report generation, alerting, automation, automatic deployment onto servers, and certificate enrollment add layers of sophistication, making it a versatile and intelligent asset.