Primordial magnetic fields and CP violation in the sky

It has been argued that electroweak baryogenesis generates a left-handed primordial magnetic field. The helicity density of the primordial magnetic field today is estimated to be $\sim {10}^2{n}_b$ where $n_b\sim {10}^{-6}$ /cm${}^3$ is the present cosmological baryon number density. With certain assumptions about the inverse cascade the field strength at recombination is $\sim 10^{-13}$Gonacoherencescale$\sim 10^{-4}$ pc. Here I discuss the various assumptions made in obtaining these estimates and the concomitant open issues.