"The results show that free-form gesture passwords are a serious alternative to text or other log-in methods, especially for mobile devices," said Janne Lindqvist, study co-author. Free-form gesture passwords are very suitable for touchscreens, faster to use, easy to remember and hard to guess.

"Getting access to somebody's phone can give a lot of information about that person and make them vulnerable to lots of different kinds of attacks than can have financial and other repercussions," Lindqvist added.

For the study, the team installed software on Android smartphones of 91 who created 347 text passwords and 345 gesture passwords. They completed 2,002 log-in tasks involving eight virtual accounts in their smartphones.

The results showed that the participants preferred shapes (49.28 percent) and letters (24.07 percent) for their gesture passwords versus lines (15.76 percent). Participants also preferred single-finger gestures (93.62 percent) over multi-finger ones.

Participants who used gesture passwords spent 22 percent less time logging in and 42 percent less time creating passwords, on average.

Free-form gestures could be expanded to laptops and tablet/laptop combos with touch screens - even doors with touch screens instead of key locks or swipe cards. The findings will be shared at the Association for Computing Machinery's "Conference on Human Factors in Computing Systems" in San Jose, California, in May.