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SSL certificate revocation list

This section provides information on identifying directives for certificate revocation list (CRL) and those supported in global servers and virtual hosts.

Certificate revocation provides the ability to revoke a client certificate given to IBM HTTP Server by the browser when the key becomes compromised or when access permission to the key gets revoked. CRL represents a database which contains a list of certificates revoked before their scheduled expiration date.

To enable certificate revocation in IHS, publish the CRL on a LDAP server. Once the CRL is published to an LDAP server, you can access the CRL using the IHS configuration file. The CRL determines the access permission status of the requested client certificate.

Identifying directives needed to set up a certificate revocation list.

The SSLClientAuth directive can include two options at once:

• SSLClientAuth 2 crl
• SSLClientAuth 1 crl

The CRL option turns CRL on and off inside an SSL virtual host. If we specify CRL as an option, then you elect to turn CRL on. If we do not specify CRL as an option, then CRL remains off. If the first option for SSLClientAuth equals 0/none, then you cannot use the second option, CRL. If we do not have client authentication on, then CRL processing does not take place.

Identifying directives supported in global or server and virtual host.

Global server and virtual host support the following directives:

• SSLCRLHostname: The IP Address and host of the LDAP server, where the CRL database resides.
• SSLCRLPort: The port of the LDAP server where the CRL database resides; the default equals 389.
• SSLCRLUserID: The user ID to send to the LDAP server where the CRL database resides; defaults to anonymous if we do not specify the bind.
• SSLStashfile: The fully qualified path to file where the password for the user name on the LDAP server resides. This directive is not required for an anonymous bind. Use when you specify a user ID.

  Use the sslstash command, located in the bin of IHS, to create your CRL password stash file. The password you specify using the sslstash command should equal the one you use to log in to your LDAP server.

  Usage:

  sslstash [-c] <directory_to_password_file_and_file_name> <function_name> <password>

  ...where:

  -c	Creates a new stash file. If not specified, an existing file updates.
  File	Represents the fully qualified name of the file to create, or update.
  Function	Indicates the function for which to use the password. Valid values include crl, or crypto.
  Password	Represents the password to stash.

CRL checking follows the URIDistributionPoint X509 extension in the client certificate as well as trying the DN constructed from the issuer of the client certificate. If the certificate contains a CRL Distribution Point (CDP), then that information is given precedence. The order in which the information is used is as follows:

1. CDP LDAP X.500 name

2. CDP LDAP URI

3. Issuer name combined with the value from the SSLCRLHostname directive

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Related concepts

Certificates

 

Related reference

SSL directives