# Certificate Revocation Lists

All certificates are issued for a restricted period of time. However it may happen that a certificate should not be used or becomes invalid before the not after time in the certificate is reached. In this case the issuing CA should revoke this certificate by putting it on the list of revoked certificates, signing the list and publishing it.

## Generation of CRLs

In XCA this can be done by the context-menu of the CA and the revoke entry in the context-menu of the issued certificate. First all invalid certificates must be marked as revoked and then a Certificate Revocation List should be created and will be stored in the database.

The validity times define start and expiry date of the CRL. The default interval can be configured in the CA Properties dialog.

The options section allows to select, whether the Subject Alternative Name and the Authority Key Identifier of the issuing CA should be placed into the CRL. The CRL Number (https://tools.ietf.org/html/rfc5280#section-5.2.3) will be tracked by XCA and updated on every use.

There is also a commandline option to issue a CRL:

    xca --crlgen="My Ca" --pem --print

## CRL Export

Certificate Revocation Lists can be exported by the context-menu or by the button on the right.

- Clipboard Writes all selected requests in PEM format to the Clipboard.

- File: Write the request into a file. The filename can be selected in the export dialog and the Export format:

> - PEM: (*.crl) PEM Text format with headers

> - DER: (*.der) Binary DER format of the revocation list

> - vCalendar: (*.ics) vCalendar reminder for the CRL expiry date

## Manage revocations

Revoked certificates may be managed without the revoked certificate in the database. The revocations are stored inside the database for each CA with revocation date, revocation reason and invalidation date. They get automatically updated when importing a CRL of this CA or by manually revoking an issued certificate. The Manage revocations dialog is accessible by the CA submenu of the context menu of the CA. Entries can be added, deleted and modified.

## Revocation properties

The certificate revocation happens by the CA at the revocation date which is the time when the revocation is performed. The invalidity date can be set to an earlier time in this dialog. The revocation reason is explains why the certificate has been revoked. https://tools.ietf.org/html/rfc5280#section-5.3