  We consider a dark electroweak phase transition, during which a baryon
asymmetry in the dark neutrons and an equal lepton asymmetry in the dark Dirac
neutrinos can be simultaneously induced by the CP-violating reflection of the
dark fermions off the expanding dark Higgs bubbles. The Yukawa couplings for
generating the ordinary Majorana neutrino masses can partially convert the dark
lepton asymmetry to an ordinary baryon asymmetry in association with the
ordinary sphaleron processes. The dark neutron can have a determined mass to
serve as a dark matter particle. By further imposing a proper mirror symmetry,
the Majorana neutrino mass matrix can have a form of linear seesaw while its
Dirac CP phase can provide a unique source for the required CP violation.
