Windows 8 security takes on different strokes

Windows 8 has been outfitted with a password gesture log-in platform that Microsoft says is tough to crack.

The scheme uses circles, lines and dots defined by users and mapped on images as a replacement for text passwords.

Microsoft said the patterns were easier for users to memorise and more complex than text passwords.

The minimum three gestures required could produce a billion possible unique combinations compared to a three digit “complex” password that could generate 81 thousand combinations, Microsoft program manager Zach Pace said.

And the numbers scale. A gesture password that includes five shapes could produce 398 trillion combinations while a five character complex password would produce 183 million combinations.

A combination is authenticated if the inputted gestures are 90 per cent accurate.

Lines had more combinations than circles, while dots had the least.

Microsoft binned plans to allow free form design which would introduce more entropy because field tests revealed users stuggled to duplicate gestures.

They also spent too long attempting to pefecting mimic gestures instead of faster swipes used in the current system.

The system can be set to accept text passwords and will fail over to the format after five incorrect gesture guesses.

While the numbers look impressive, it raises the possibility that attackers could watch users input gestures from “points of interest” – like noses, eyes and hands.

But Pace said mimicking “points of interest” does not work in practice.

“The areas people chose and the kind of gestures they drew upon them correlated very poorly in the lab,” he said.

“Assuming the average image has 10 points of interest, and a gesture sequence length of three, there are 8 million possible combinations, making the prospect of guessing the correct sequence within five tries fairly remote.”

Following smudge marks for touchscreen devices fails too. Even in perfect conditions where only password smudges remain, each gesture could be swiped differently.

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