OMEMO is the next generation of end-to-end encryption method for IM applications, which supersedes OTR. Compare to OTR, OMEMO provides many useful new features.
Currently, the support for libpurple is still in development. I found two projects - lurch and libpurple-omemo-plugin. They are in early phase so it is probably not very stable and few features are missing.
Research on OMEMO for libpurple
