The following is designed to work on in a Linux environment. Read carefully before proceeding so that you understand the process. Several restarts of tomcat and/or apache are required. Backup your entire Shibboleth installation (and snapshot your server if possible) before proceeding.
NOTE WELL: The following instructions are pretty much untested at present and assumes that you are running Shibboleth IdP 2.3 or later.
Change into the IdP distribution directory, shibboleth-identityprovider-VERSION. This is the directory you created when you installed or last updated the IdP. Run the following using the appropriate user that can write to your Shibboleth installation
Respond to the prompts appropriately. The new private key, long lived certificate, and keystore files will be generated with the file name suffix '.new'.
Backup your metadata file (adjust the paths to reflect your own installation)
sudo cp /opt/shibboleth-idp/metadata/idp-metadata.xml /opt/shibboleth-idp/metadata/idp-metadata.xml.bak.0
Paste the new certificate in, omitting the -----BEGIN CERTIFICATE----- and -----END CERTIFICATE----- lines. Do this two times, once in the IDPSSODescriptor and once in the AttributeAuthorityDescriptor element.
Restart your IdP, Send the metadata file to email@example.com. Wait for operations to add the metadata into the appropriate stream.
Once the stream has updated (allow 24 hours), switch the metadata used by the IdP. Backup the old files.
sudo mv /opt/shibboleth-idp/credentials/idp.key /opt/shibboleth-idp/credentials/idp.key.bak.0
sudo mv /opt/shibboleth-idp/credentials/idp.crt /opt/shibboleth-idp/credentials/idp.crt.bak.0
sudo mv /opt/shibboleth-idp/credentials/idp.jks /opt/shibboleth-idp/credentials/idp.jks.bak.0
Activate the new files
sudo mv /opt/shibboleth-idp/credentials/idp.key.new.key /opt/shibboleth-idp/credentials/idp.key
sudo mv /opt/shibboleth-idp/credentials/idp.crt.new.crt /opt/shibboleth-idp/credentials/idp.crt
sudo mv /opt/shibboleth-idp/credentials/idp.jks.new.jks /opt/shibboleth-idp/credentials/idp.jks
If you use tomcat alone, make sure it can access the idp.jks file. If you have an Apache front, check the VirtualHost configuration for port 8443 can access the key and crt files. Update your Tomcat/Apache configuration if you have changed the passphrase. Restart Apache and/or Tomcat and test. If everything works, you can remove the old certificate from the IdP's metadata and re-submit the metadata to firstname.lastname@example.org so that the old certificate is removed from the stream.