Much has been written about the insecurity of passwords. Aside from being guessable, people are regularly tricked into providing their passwords to rogue servers because they can’t distinguish spoofed windows and webpages from legitimate ones.
Here’s a clever scheme by Rachna Dhamija and Doug Tygar at the University of California Berkeley that tries to deal with the problem. It’s called “Dynamic Security Skins,” and it’s a pair of protocols that augment passwords.
First, the authors propose creating a trusted window in the browser dedicated to username and password entry. The user chooses a photographic image (or is assigned a random image), which is overlaid across the window and text entry boxes. If the window displays the user’s personal image, it is safe for the user to enter his password.
Second, to prove its identity, the server generates a unique abstract image for each user and each transaction. This image is used to create a “skin” that automatically customizes the browser window or the user interface elements in the content of a webpage. The user’s browser can independently reach the same image that it expects to receive from the server. To verify the server, the user only has to visually verify that the images match.
Not a perfect solution by any means—much Internet fraud bypasses authentication altogether—but two clever ideas that use visual cues to ensure security. You can also verify server authenticity by inspecting the SSL certificate, but no one does that. With this scheme, the user has to recognize only one image and remember one password, no matter how many servers he interacts with. In contrast, the recently announced Site Key (Bank of America’s implementation of the Passmark scheme) requires users to save a different image with each server.