You can now enable official SSL certificate with your custom domain. This future is currently in beta, but every blogger can use it via

  1. First go to
  2. Go to setting, then basic and choose yes in HTTPS availability.
  3. Now go back to your main blogger dashboard(
  4. Now wait for few minutes, and you can see same option there as well, so choose yes in both option. I enable it in just 2 minute, but it may take long time for your blog, because they register your SSL certificate automatically for your custom domain.