In the new browser war, privacy is a crucial battleground.

Mozilla’s Firefox, Google’s Chrome, Microsoft’s Internet Explorer and Apple’s Safari all compete to give users the most control over their online identities and the best protection from Web sites that use “cookies,” those unique identifiers that can track users online.

So how effective are the newest batch of browser privacy tools? Kate McKinley, a researcher at iSec Partners, a San Francisco security firm, sought to find out.

In a paper published Tuesday, Ms. McKinley found particular problems with Safari and concluded that none of the four major browsers extends its privacy protections to Adobe’s immensely popular Flash plug-in, which is used to display Web animations and video.

Apple’s Safari fared the worst of the browsers in Ms. McKinley’s tests. When used in “private browsing mode” on a Macintosh running OS X, Safari was “quirky,” Ms. McKinley wrote, accessing some of the cookies previously stored on her computer, but not others. When used on a machine running Windows XP, Safari’s private browsing mode was not private at all -– it accessed previously set cookies and did not delete any new ones.

Source [ New York Times ]