A certificate authority selection unit implements a method for selecting one of a plurality of certificate authorities servicing a plurality of administrative domains in a communication system. The method includes: receiving, from an end-entity via an interface, a certificate service request associated with an identifier; selecting, based on the identifier, one of the plurality of administrative domains in the communication system, wherein the plurality of administrative domains are serviced by a plurality of certificate authorities; retrieving a security profile for the end-entity; and selecting, based on the security profile for the end-entity, one of the plurality of certificate authorities to process the certificate service request.