Computer Configuration > Administrative Templates > Firefox > Content Analysis (DLP)
Both
HKLM\Software\Policies\Mozilla\Firefox\ContentAnalysis
If this policy is enabled, you can set the required signature of the DLP agent connected to the pipe. If this is a non-empty string and the DLP agent does not have a signature with a Subject Name that exactly matches this value, Firefox will not connect to the pipe. If this policy is disabled or not configured, the signature will not be verified.