The experience of signing in to your PC with touch has traditionally been a cumbersome one. In a world with increasingly strict password requirements—with numbers, symbols, and capitalization—it can take upwards of 30 seconds to enter a long, complex password on a touch keyboard. We have a strong belief that your experience with Windows 8 should be both fast and fluid, and that starts when you sign in.
Other touch experiences in the marketplace have tried to tackle this problem, with the canonical example being a numeric PIN. A PIN is a great solution: Almost everyone has seen or used one before, and a keypad is simple to use with touch. We knew though, that there was room to improve.
A numeric combination often presents a problem for people because the sequences easiest to remember are typically the least secure. Common number sequences—like 1111, or 1234—are troublesome, but PINs that are composed of common well-known personal dates can also be deduced if an attacker has personal knowledge of the person (much of which is not hard to obtain). In such a case, the number being personal to a person can work against its security. We set out to change the paradigm here: we designed a fast and fluid touch sign-in experience that is also personal to you.
A personal sign-in experience
At its core, your picture password is comprised of two complimentary parts. There is a picture from your picture collection and a set of gestures that you draw upon it. Instead of having you pick from a canned set of Microsoft images, you provide the picture, because it increases both the security and the memorability of the password. You get to decide the content of the picture and the portions that are important to you. Plus, you get to see a picture that is important to you just like many people do on their phone lock screen.
The full story and more details about the technology behind it, can be found at the Microsoft site.