What is this all about: web privacy. We are tracked everywhere, and i'd like to help if possible. So, let's design a web browser that for once respects your privacy.

Main features:

• Each website has its own cookie jar, its own cache and its own HTML5 local storage
• History related css attributes are disabled
• External plugins are only enabled on demand
• Support for Tor/I2P is enabled by default
• You have complete control over who receives what information
• Let's you control in the settings if you want to allow referrers or not.
• The contextual menu let's you open links anonymously (no referrer, anonymous session)

The browser is bundled with a particular UI that let you control everything during your browsing session. it is non intrusive and makes the best choice by default. I am thinking of a notification bar that shows at the bottom. I noticed that this place is not intrusive when I realized that the search bar in Firefox was most of the time open, even if most of the time I didn't use it.

First, let's define a session:

• A session can be used my more than one domain at the same time.
• A session is associated to a specific cache storage
• A session is associated to a specific HTML5 storage
• A session is associated to a specific cookie jar
• A session acn be closed. When it is closed, session cookies are deleted from the session
• A session can be reopened. All long lasting cookies, cache, HTML5 storage and such is then used again.
• A session can be anonymous. In such a case, the session is deleted completely when it is closed.
• A session is associated to none, one or more domains. These domains are the domains the end user can see in the address bar, not the sub items in the page.

Sessions are like Firefox profiles. If you iopen a new session, it's like you opened a new Firefox profile you just created. Because people will never create a different Firefox profile for each site.

If we want to protect privacy, when a link is opened, a new session should be created each time. To make it usable to browse web sites, it is made possible to share sessions in specific cases. Let's define the cases where it might be intelligent to share a profile:

• You click a link or submit a form and expect to still be logged-in in the site you are viewing. You don't care if you follow a link to an external page.

  User Interface: If the link matches one of the domains of the session, then keep the session. No UI. If the user wanted a new session, the "Open anonymously" entry in the context menu exists. A button on the toolbar might be available to enter a state where we always want to open links anonymously.

  If the link points to another domain, then open the link in a new session unless "Open in the same session" was specified in the context menu. The UI contains:

  We Protected your privacy by separating <domain of the new site> from
  the site you were visiting previously (<domain of the previous site>).
  
  Choices: [ (1) Create a new anonymous session          | ▼ ]
           | (2) Continue session from <previous domain> |
           | (3) Use a previous session for <new domain> |
           | (4) Use session from bookmark "<name>"      |
  

  The first choice is considered the default and the page is loaded with it. If the user chooses a new option, then the page is reloaded.

  If the user chooses (2), the page is reloaded with the previous session and the user will be asked if "Do you want and to have access to the same private information about you?". Answers are Yes, No and Always. If the answer is Always, then in the configuration, the two domains are considered one and the same.

  The choice (3) will use the most recent session for the new domain. It might be a session currently in use or a session in the history.

  There are as many (4) options as there are bookmarks for the new domain. If different bookmarks share a single session, only one bookmark is shown. This choice will load the session from the bookmark.

  If (3) and (4) are the same sessions, and there is only one bookmark (4), then the (4) option is left out.

• You use a bookmark and expect to continue the session you had for this bookmark (webmails)

  The session is simpely stored in the bookmark. When saving a bookmark, there is an option to store the session with it or not.

  [X] Do not save any personal information with this bookmark
  

• You open a new URL and you might want reuse a session that was opened for this URL.

  The User Interface allows you to restore the session:

  We protected your privacy by not sending any personal information to
  <domain>. If you want <domain> to receive private information, please
  select:
  
  Choices: [ Do not send private information     | ▼ ]
           | Use a previous session for <domain> |
           | Use session from bookmark "<name>"  |
  

If you can see other use cases, please comment on that.

From these use cases, I can infer three kind of sessions:

• Live sessions, currently in use
• Saved sessions, associated to a bookmark
• Closed sessions in the past, accessible using history. Collected after a too long time.

Now, how to implement that? I was thinking of QtWebKit as I already worked with Qt and it's easy to work with.

• We have a main widget: QWebView. We want to change the session when a new page is loaded. So we hook up with the signal loadStarted.
• We prevent history related CSS rules by implementing QWebHistoryInterface, more specifically, we store the history necessary to implement QWebHistoryInterface in the session.
• We change the cache by implementing QAbstractNetworkCache and setting it using view->page()->networkAccessManager()->setCache(...)
• We change the cookie jar by implementing QNetworkCookieJar and setting it using view->page()->networkAccessManager()->setCookieJar(...)
• Change the local storage path using a directory dedicated for the session and using view->page()->settings()->setLocalStoragePath(QString)

After all that, we'll have to inspect the resulting browser to determine if there are still areas where we fail at protecting privacy.