Proceedings
The proceedings will be published in Springer's Lecture Notes in Computer Science series. They will be published in two volumes with numbers 6914 and 6915. Those volumes are available online:
For free access to the proceedings first log into Springer's IACR reading room, then click on the PKC tab, choose PKC 2015 (for the moment; PKC 2016 is not linked there, yet), then enter "PKC 2016" in the search mask and (voilà) you will see links to the proceedings.