X-PGP-Sig header utility for Emacs. It can insert/verify PGP signatures in the X-PGP-Sig: mail/news header. x-pgp-sig.el is for MH(mh-e, Mew and so on), Gnus, Semi-gnus, wl(Wanderlust) VM, cmail etc... (MUA on Emacs).

English documentation is not available, only Japanese.