28.10. Requesting a new user certificate from an IdM sub-CA and exporting it to the client

Procedure

1. Optional: Create a new directory, for example ~/certdb/, and make it a temporary certificate database. When asked, create an NSS Certificate DB password to encrypt the keys to the certificate to be generated in a subsequent step:

   # mkdir ~/certdb/
   # certutil -N -d ~/certdb/
   Enter a password which will be used to encrypt your keys.
   The password should be at least 8 characters long,
   and should contain at least one non-alphabetic character.
   
   Enter new password:
   Re-enter password:

2. Create the certificate signing request (CSR) and redirect the output to a file. For example, to create a CSR with the name certificate_request.csr for a 4096 bit certificate for the idm_user user in the IDM.EXAMPLE.COM realm, setting the nickname of the certificate private keys to idm_user for easy findability, and setting the subject to CN=idm_user,O=IDM.EXAMPLE.COM:

   # certutil -R -d ~/certdb/ -a -g 4096 -n idm_user -s "CN=idm_user,O=IDM.EXAMPLE.COM" > certificate_request.csr

3. When prompted, enter the same password that you entered when using certutil to create the temporary database. Then continue typing randomly until told to stop:

   Enter Password or Pin for "NSS Certificate DB":
   
   A random seed must be generated that will be used in the
   creation of your key.  One of the easiest ways to create a
   random seed is to use the timing of keystrokes on a keyboard.
   
   To begin, type keys on the keyboard until this progress meter
   is full.  DO NOT USE THE AUTOREPEAT FUNCTION ON YOUR KEYBOARD!
   
   
   Continue typing until the progress meter is full:

4. Submit the certificate request file to the server. Specify the Kerberos principal to associate with the newly-issued certificate, the output file to store the certificate, and optionally the certificate profile. Specify the IdM sub-CA that you want to issue the certificate. For example, to obtain a certificate of the IECUserRoles profile, a profile with added user roles extension, for the idm_user@IDM.EXAMPLE.COM principal from webclient-ca, and save the certificate in the ~/idm_user.pem file:

   # ipa cert-request certificate_request.csr --principal=idm_user@IDM.EXAMPLE.COM --profile-id=IECUserRoles --ca=webclient-ca --certificate-out=~/idm_user.pem

5. Add the certificate to the NSS database. Use the -n option to set the same nickname that you used when creating the CSR previously so that the certificate matches the private key in the NSS database. The -t option sets the trust level. For details, see the certutil(1) man page. The -i option specifies the input certificate file. For example, to add to the NSS database a certificate with the idm_user nickname that is stored in the ~/idm_user.pem file in the ~/certdb/ database:

   # certutil -A -d ~/certdb/ -n idm_user -t "P,," -i ~/idm_user.pem

6. Verify that the key in the NSS database does not show (orphan) as its nickname. For example, to verify that the certificate stored in the ~/certdb/ database is not orphaned:

   # certutil -K -d ~/certdb/
   < 0> rsa      5ad14d41463b87a095b1896cf0068ccc467df395   NSS Certificate DB:idm_user

7. Use the pk12util command to export the certificate from the NSS database to the PKCS12 format. For example, to export the certificate with the idm_user nickname from the /root/certdb NSS database into the ~/idm_user.p12 file:

   # pk12util -d ~/certdb -o ~/idm_user.p12 -n idm_user
   Enter Password or Pin for "NSS Certificate DB":
   Enter password for PKCS12 file:
   Re-enter password:
   pk12util: PKCS12 EXPORT SUCCESSFUL

8. Transfer the certificate to the host on which you want the certificate authentication for idm_user to be enabled:

   # scp ~/idm_user.p12 idm_user@client.idm.example.com:/home/idm_user/

9. On the host to which the certificate has been transferred, make the directory in which the .pkcs12 file is stored inaccessible to the 'other' group for security reasons:

   # chmod o-rwx /home/idm_user/

10. For security reasons, remove the temporary NSS database and the .pkcs12 file from the server:

    # rm ~/certdb/
    # rm ~/idm_user.p12