In a shift aimed at fostering wider use of encryption on the Web, Google is tweaking its search engine to favor sites that use HTTPS to protect end users' privacy and security.

Sites that properly implement the transport layer security (TLS) protocol may be ranked higher in search results than those that transmit in plaintext, company officials said in a blog post published Wednesday. The move is designed to motivate sites to use HTTPS protections across a wider swath of pages rather than only on login pages or not at all. Sites that continue to deliver pages over unprotected HTTP could see their search ranking usurped by competitors that offer HTTPS. Facebook is also getting more serious about encryption, with plans to acquire PrivateCore, a company that develops encryption software to protect and validate data stored on servers.

In Wednesday's post, Google Webmaster Trends Analysts Zineb Ait Bahajji and Gary Illyes noted that Google was among the first sites to offer end-to-end HTTPS protection by default across virtually all of its properties. It has also offered a variety of tools to help sites detect and recover from security breaches. They went on to write:

We want to go even further. At Google I/O a few months ago, we called for “HTTPS everywhere” on the web. We’ve also seen more and more webmasters adopting HTTPS (also known as HTTP over TLS, or Transport Layer Security), on their website, which is encouraging. For these reasons, over the past few months we’ve been running tests taking into account whether sites use secure, encrypted connections as a signal in our search ranking algorithms. We’ve seen positive results, so we’re starting to use HTTPS as a ranking signal. For now it's only a very lightweight signal—affecting fewer than one percent of global queries and carrying less weight than other signals such as high-quality content—while we give webmasters time to switch to HTTPS. But over time, we may decide to strengthen it, because we’d like to encourage all website owners to switch from HTTP to HTTPS to keep everyone safe on the Web. In the coming weeks, we’ll publish detailed best practices (we’ll add a link to it from here) to make TLS adoption easier, and to avoid common mistakes. Here are some basic tips to get started: Decide the kind of certificate you need: single, multi-domain, or wildcard certificate

Use 2048-bit key certificates

Use relative URLs for resources that reside on the same secure domain

Use protocol relative URLs for all other domains

Check out our Site move article for more guidelines on how to change your website’s address

Don’t block your HTTPS site from crawling using robots.txt

Allow indexing of your pages by search engines where possible. Avoid the noindex robots meta tag If your website is already serving on HTTPS, you can test its security level and configuration with the Qualys Lab tool. If you are concerned about TLS and your site’s performance, have a look at Is TLS fast yet?. And of course, if you have any questions or concerns, please feel free to post in our Webmaster Help Forums.

TLS provides two major advantages over non-encrypted Internet traffic. First, by encrypting the data as it travels between end users and servers, it prevents third parties who have the capability to monitor the connection from being able to read or tamper with the content. TLS also provides a means for cryptographically validating that a server claiming to belong to Google, Bank of America, or any other website is authentic, rather than an impostor set up to trick users.

Over the past few years, American Civil Liberties Union Principal Technologist Chris Soghoian has used a carrot-and-stick approach to persuade more sites to HTTPS-protect their pages. He sometimes publicly chastises companies that transmit sensitive information over unencrypted connections. And he has offered whiskey to webmasters in exchange for them adopting the measure. Google's move is made in the same spirit, but it's likely to have a much bigger effect. Companies devote huge amounts of resources to search engine optimization. Those that so far have ignored calls to implement HTTPS may finally heed them if they believe it will help their pages rise above those of their competitors in the all-important Google search rankings.