The Security of Quantum Key Distribution using a Simplified Trusted   Relay
  We propose a QKD protocol for trusted node relays. Our protocol shifts the communication and computational weight of classical post-processing to the end users by reassigning the roles of error correction and privacy amplification, while leaving the exchange of quantum signals untouched. We perform a security analysis for this protocol based on the BB84 protocol on the level of infinite key formulas, taking into account weak coherent implementations involving decoy analysis. 
William Stacey, Razieh Annabestani, Xiongfeng Ma, Norbert L\"utkenhaus
quant-ph