  Collaboration among multiple organizations is imperative for contemporary
intrusion detection. As modern threats become well sophisticated it is
difficult for organizations to defend with threat context local to their
networks alone. Availability of global \emph{threat intelligence} is must for
organizations to defend against modern advanced persistent threats (APTs). In
order to benefit from such global context of attacks, privacy concerns continue
to be of major hindrance. In this position paper we identify real world privacy
problems as precise use cases, relevant cryptographic technologies and discuss
privacy preserving architectures for collaborative intrusion detection.
