I gave a talk at Ekoparty 12 on 2016 October 26 about the Letter Sealing end-to-end encrypted messaging feature used in LINE and about reverse engineering their applications (especially the Chrome app since it's so much easier than the others) to figure out the details about the protocol that hadn't been published.

I'll probably add more information about it and any further research into LINE in the future, but for now, here are the slides from the talk.