PERC stands for Privacy Enhanced RTP Conferencing.

PERC is a proposed IETF draft that allows hop-by-hop and end-to-end security guarantees simultaneously.

This type of a scheme is useful in group sessions where the media server (SFU) used to route the media is considered un-trusted by the participants of the session. The way it works is by using two separate encryption keys – one for end-to-end privacy between the participants of the session and the other for hop-by-hop.