With the move to https:// for website, there's some clear guidelines that Google recommend. Here's the article.
What is https:// (from Google)
HTTPS (Hypertext Transfer Protocol Secure) is an internet communication protocol that protects the integrity and confidentiality of data between the user's computer and the site. Users expect a secure and private online experience when using a website. We encourage you to adopt HTTPS in order to protect your users' connection to your website, regardless of the content on the site.
Data sent using HTTPS is secured via Transport Layer Security protocol (TLS), which provides three key layers of protection:
- Encryption—encrypting the exchanged data to keep it secure from eavesdroppers. That means that while the user is browsing a website, nobody can "listen" to their conversations, track their activities across multiple pages, or steal their information.
- Data integrity—data cannot be modified or corrupted during transfer, intentionally or otherwise, without being detected.
- Authentication—proves that your users communicate with the intended website. It protects against man-in-the-middle attacks and builds user trust, which translates into other business benefits.