There is a new version of zdkimfilter. http://www.tana.it/sw/zdkimfilter/ Reproducible: Always
*** Bug 579108 has been marked as a duplicate of this bug. ***
Created attachment 493220 [details] ebuild for 1.5 this is ebuild use personally, just works, no guarantee.
I used the ebuild for 1.5 with zdkimfilter 1.6 (current release) and it works well, even with current nettle (which was a problem for me previously).
Package removed.
FYI I re-added an ebuild for the latest version of zdkimfilter to portage and will take care of it.