Google has announced in August 2014 that SSL/HTTPS is now an official ranking signal. Although it probably doesn’t have as much weight as let’s say, high-quality content, it is indeed a ranking signal nonetheless. What’s monumental about this announcement is that Google never ever openly states their ranking algorithm’s factors, but for this major movement towards a safer web, they couldn’t resist. Google now gives preferential treatment to websites and pages secured by trusted SSL certificates and it is now the easiest thing a site owner can do to boost SEO rankings.
See: HTTPS as a ranking signal