HTTPS Everywhere is a Firefox add-on produced as a collaboration between The Tor Project (https://www.torproject.org) and the Electronic Frontier Foundation (https://eff.org/). It encrypts your communications with a number of major Web sites, including Google, Wikipedia, and popular social networking platforms such as Facebook and Twitter.
Many sites on the Web offer some support for encryption over HTTPS, but make it difficult to use. For instance, they may connect you to HTTP by default, even when HTTPS is available. Alternatively, they may fill encrypted pages with links that go back to the unencrypted site. This way, data (such as usernames and passwords) sent to and received by these Web sites are transferred as plain text and are easy to read by third parties.
The HTTPS Everywhere extension fixes these problems by rewriting all requests to these sites to HTTPS. (Although the extension is called "HTTPS Everywhere", it only activates HTTPS on a particular list of sites and can only use HTTPS on sites that have chosen to support it. It cannot make your connection to a site secure if that site does not offer HTTPS as an option.)
Please note that some of those sites still include a lot of content, such as images or icons, from third party domains that is not available over HTTPS. As always, if the browser's lock icon is broken or carries an exclamation mark, you may remain vulnerable to some adversaries that use active attacks or traffic analysis. However, the effort required to monitor your browsing should still be usefully increased.
Some Web sites (such as Gmail) provide HTTPS support automatically, but using HTTPS Everywhere will also protect you from SSL-stripping attacks, in which an attacker hides the HTTPS version of the site from your computer if you initially try to access the HTTP version.
Additional information can be found at: https://www.eff.org/https-everywhere.
First, download the HTTPS Everywhere extension from the official Web site: https://www.eff.org/https-everywhere.
Select the newest release. In the example below, version 0.9.4 of HTTPS Everywhere was used. (A newer version may be available now.)
Click on "Allow". You will then have to restart Firefox by clicking on the "Restart Now" button. HTTPS Everywhere is now installed.
To access the HTTPS Everywhere settings panel in Firefox 4 (Linux), click on the Firefox menu at the top left on your screen and then select Add-ons Manager. (Note that in different versions of Firefox and different operating systems, the Add-ons Manager may be located in different places in the interface.)
Click on the Options button.
A list of all supported Web sites where HTTPS redirection rules should be applied will be displayed. If you have problems with a specific redirection rule, you can uncheck it here. In that case, HTTPS Everywhere will no longer modify your connections to that specific site.
Once enabled and configured, HTTPS Everywhere is very easy and transparent to use. Type in an insecure HTTP URL (for example, http://www.google.com).
Press Enter. You will be automatically redirected to the secure HTTPS encrypted Web site (in this example: https://encrypted.google.com). No other action is needed.
If networks block HTTPS
Your network operator may decide to block the secure versions of Web sites in order to increase its ability to spy on what you do. In such cases, HTTPS Everywhere could prevent you from using these sites because it forces your browser to use only the secure version of these sites, never the insecure version. (For example, we heard about an airport Wi-Fi network where all HTTP connections were permitted, but not HTTPS connections. Perhaps the Wi-Fi operators were interested in watching what users did. At that airport, users with HTTPS Everywhere were not able to use certain Web sites unless they temporarily disabled HTTPS Everywhere.)
In this scenario, you might choose to use HTTPS Everywhere together with a circumvention technology such as Tor or a VPN in order to bypass the network's blocking of secure access to Web sites.
Adding support for additional sites in HTTPS Everywhere
You can add your own rules to the HTTPS Everywhere add-on for your favorite Web sites. You can find out how to do that at: https://www.eff.org/https-everywhere/rulesets. The benefit of adding rules is that they teach HTTPS Everywhere how to ensure that your access to these sites is secure. But remember: HTTPS Everywhere does not allow you to access sites securely unless the site operators have already chosen to make their sites available through HTTPS. If a site does not support HTTPS, there is no benefit in adding a ruleset for it.
If you are managing a Web site and have made an HTTPS version of the site available, a good practice would be to submit your Web site to the official HTTPS Everywhere release.