Part 6: Prevent Duplicate Certificates

The following covers how to prevent duplicate certificates from being generated by using Custom Certificate Extensions enabled in the Certificate Profile.

Stop Duplicate Certificates from Being Generated

To stop the duplicate certificates from being generated, perform the following steps:

  1. In EJBCA, click System Configuration and select the Custom Certificate Extensions tab.
  2. Specify the following and then click Add:
    1. In Object Identifier (OID), specify 1.3.6.1.4.1.311.21.7.
    2. In Label, specify User Certificate Template Information.
  3. Click Edit on the object added, and specify the following:
    1. Select the Encoding to DEROBJECT.
    2. Enable Dynamic.
  4. Open PowerShell on the CS Host and run the following to obtain the Certificate Template OIDs:
    Certutil -catemplates -v | select-string displayname,msPKI-Cert-Template-OID
  5. Copy the portion of the user template OID string following "1.3.6.1.4.1.311.21.8.". 
  6. On the Custom Certificate Extensions tab, paste the copied OID string in the Properties table Value field.

    For example, for the following OID:
     1.3.6.1.4.1.311.21.8.14060797.2478758.7163562.12957827.1390504.234.13270651.167227
    paste the following in the Value field:
    14060797.2478758.7163562.12957827.1390504.234.13270651.167227
  7. Click Save.
  8. Repeat these steps for the Computer Auto Enrollment template, specifying Computer Certificate Template Information as the label, and obtaining the value from the Computer template OID.

Enable Custom Extensions in Certificate Profile

To enable the Custom Extensions in the Certificate Profile, perform the following steps:

  1. Click CA Functions > Certificate Profiles.
  2. Click Clone next to the ENDUSER Certificate Profile and name the new profile User_Certificate_Profile (or select the Certificate Profile already being used).
  3. Click Edit for the User_Certificate_Profile and specify the following:
    1. Key Usage: Digital Signature, Non-repudiation, and Key encipherment (if not already selected).
    2. Extended Key Usage: Client Authentication, Email Protection, and MS Encrypted File System (EFS).
    3. Used Custom Certificate Extensions: User Certificate Template Information.
    4. Available CAs: Issuing CA.
  4. Click Save to save the User Certificate Profile.