I think we just have to found the fifth key, and not the others.
A few months ago from what i understood , the co-founder and creative directof of redlynx ( anba ) hidden 4 keys around the world, and gps coordinates was given on this weird website :
http://www.fixedpatternencodes.com/Then the community have found theses little chests :
One of them made a video :
https://www.youtube.com/watch?feature=player_embedded&v=...But the most intersting part was the chest in helsinki, there was some documents in old french language about a transaction, AND a picture inside this chest :
http://image.noelshack.com/fichiers/2013/41/1381546832-....jpgThe background looks like the fusion world in my opinion, and maybe the arrow show us the location of the fifth key.