HTTPS Is Now A Ranking Signal
Google now takes into account whether sites use secure, encrypted connections and are using this as a signal in the search algorithm.
On 07 Aug 2014 Google Webmasters tweeted the following on Twitter informing the public that they now use HTTPS as a ranking signal.
Google Webmasters
@googlewmc
HTTPS is now a lightweight
ranking signal: https://webmasters.googleblog.com/2014/08/https-as-ranking-signal.html
Secure those sites!
At this moment in time its lightweight, carrying far less weight than other signals. Google is giving Webmasters time to switch over to HTTPS, then they may decide to strengthen the signal. Its all about keeping people safe on the internet.
It is advised NOT to block HTTPS pages from crawlers using robots.txt, allowing indexing of your pages where possible, and to avoid the noindex robots meta tag.