A certificate contains zero or more URLs, known as distribution points, that are used by Messaging Server to locate a CRL. If the certificate does not have a CRL URL, it cannot be checked against a CRL and the private or public key is used to sign or encrypt a message without knowing its true status.
If Messaging Server fails to locate or gain access to a CRL after trying all the URLs available to it, the status of the certificate is treated as unknown. Whether a private or public key with an unknown status is used is determined by the setting of revocationunknown.
While only one CRL for each CA is supported, there can be multiple copies of the same CRL in different locations, reflected in different URLs among a user’s public key certificates. Messaging Server tries all the URL locations for a certificate until it gains access to the CRL.
You can manage multiple copies of a CRL for optimum access by periodically downloading the current CRL from the CA to a place where you want it. While you cannot change the URLs embedded in the certificates, you can redirect Messaging Server to use new CRL locations by mapping the URLs in a certificate to a new URL containing the CRL information. Create a list of one or more mapping definitions in the LDAP directory (see crlmappingurl in Table 24–3) with this syntax:
url_in_certificate is the URL in the certificate containing the old information to locate the CRL. new_url is the new URL containing the new CRL information. url_login_DN and url_login_password are the DN and password of the entry allowed access to new_url. Both are optional, and if specified, will be used for the new URL access only.
If the DN and password fails, LDAP access is denied and no retry with other credentials is attempted. These login credentials are only valid for LDAP URLs. If you use crlurllogindn and crlurlloginpw in smmime.conf, then you don’t need to specify the login DN and password in the mapping record. See 24.4.3 Accessing LDAP for Public Keys, CA certificates and CRLs Using Credentials
Only one layer of mapping is allowed. Different URLs in the certificates can be mapped to the same new URL, but you cannot assign a certificate URL to multiple new URLs. For example, the following mapping list is not valid:
msgCRLMappingRecord=URL12==URL45 msgCRLMappingRecord=URL12==URL66 msgCRLMappingRecord=URL12==URL88 msgCRLMappingRecord=URL20==URL90 msgCRLMappingRecord=URL20==URL93
The next example is a correct mapping list:
msgCRLMappingRecord=URL12==URL45 msgCRLMappingRecord=URL14==URL66 msgCRLMappingRecord=URL88==URL66 msgCRLMappingRecord=URL201==URL90 msgCRLMappingRecord=URL202==URL93
Once you have created the mapping definitions in your LDAP directory, use crlmappingurl in the smime.conf file to specify the directory information to locate them. See 24.5 Parameters of the smime.conf File.