certutil options

The command to display all certutil options that certutil -h does not disclose

certutil -uSAGE



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Automatically removing expired certificates from the CRL

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By default, AD CS will automatically remove expired certificates from the CRLs it publishes. Once a certificate expires, whether it was revoked in the past or not is generally not relevant, since the certificate is not time valid anymore it should be rejected. This default behaviour can be modified via one of the CRL flags in the CA configuration, called  CRLF_PUBLISH_EXPIRED_CERT_CRLS . By default the flag is not set, meaning expired  revoked certificates will be removed from the CRL, but it can be set running: certutil -setreg CA\CRLFlags + CRLF_PUBLISH_EXPIRED_CERT_CRLS Once set, expired revoked certificates will remain in the subsequent CRLs even after expiring. To unset the flag simply run: certutil -setreg CA\CRLFlags - CRLF_PUBLISH_EXPIRED_CERT_CRLS There are some cases, though, where it is required to keep certain revoked certificates in the CRL even after those have expired. Classic example for this is code signing certificates: when code is signed using a code signin...
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Decoding OCSP GET requests

Many clients default to OCSP requests via HTTP GET, encoding the request details as part of the URL. These kind of requests can be found in the logs: http://ocsp.ekaitza.net/ocsp/MFQwUjBQME4wTDAJBgUrDgMCGgUABBQ1uvBCJo3G3TPBvK%2BGVqszOaLAawQUb38ZjesMwNeYLEzdGvP%2FZi9TlkACE3cAEdYaIhMmuymSdxoAAAAR1ho%3D As per RFC 6960 , the request is constructed as: GET {url}/{url-encoding of base-64 encoding of the DER encoding of the OCSPRequest} So in order to find out the details of the request we have to: 1. Remove the URL encoding This can be done with different tools, depending on the OS/platform being used.Given the input above: MFQwUjBQME4wTDAJBgUrDgMCGgUABBQ1uvBCJo3G3TPBvK%2BGVqszOaLAawQUb38ZjesMwNeYLEzdGvP%2FZi9TlkACE3cAEdYaIhMmuymSdxoAAAAR1ho%3D the output would be: MFQwUjBQME4wTDAJBgUrDgMCGgUABBQ1uvBCJo3G3TPBvK+GVqszOaLAawQUb38ZjesMwNeYLEzdGvP/Zi9TlkACE3cAEdYaIhMmuymSdxoAAAAR1ho= We can then create a text file with it, e.g.:  $ echo "MFQwUjBQME4wTDAJBgUrDgMCGgUABBQ1uvBCJo3G3TPBvK+GVqsz...
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Windows automatic Root CA updates

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Microsoft runs its own Trusted Root Program , defining which Root CAs are considered trusted in Microsoft products. The list of trusted Root CAs and/or the corresponding metadata is updated regularly (updates are published here and made available for download in the form of a Certificate Trust List (CTL) here . Windows systems can be configured to automatically update their list of trusted Root CAs, via " Automatic Root Certificates Update ", a setting that can be configured via policy: gpedit.msc > Local Computer Policy > Computer Configuration > System > Internet Communication Management > Internet Communication Settings > Turn off Automatic Root Certificates Update According to the description of the policy setting, having it disabled or not configured will trigger automatic updates via the Windows Update website. The policy editor, especially when it comes to policies not configured, is not always a trustworthy source, so in case of doubt check the corr...
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