Where to find WFEncryptedEncryptionToken/CertificateThumbprint

I was manually adding things to my Microsoft.Workflow.ServiceHost.exe.config file and I accidentally overwrote the following keys :

- WFEncryptedEncryptionToken
- WFTokenEncryptionCertificateThumbprint

The new values no longer match my machine.  As a result I the service Workflow Manager Backend service won't start

How can I retrieve the old values?  Are they in the machine's certificate store or in the WF Manager databases somewhere?

Any help would be very much appreciated.

Thanks,

Rod