Bend Passwords on BendyPass: A User Authentication Method for People with Vision Impairment
Daniella Briotto Faustino, Audrey Girouard · 2018 · Proceedings of the 20th International ACM SIGACCESS Conference on Computers and Accessibility (ASSETS '18) · doi:10.1145/3234695.3241032
Summary
This demonstration paper presents BendyPass, a flexible silicone device that allows people with vision impairments to enter passwords through physical bend and fold gestures rather than typing PINs or text passwords. The project addresses a significant security concern: more than two-thirds of people with vision impairments report worrying about entering passwords in public because screen readers read characters aloud and screen magnifiers make passwords visible to bystanders, making them highly vulnerable to shoulder surfing and aural eavesdropping. BendyPass recognizes 10 simple bend gestures — bending each of its four corners upward or downward (8 gestures) and folding the device in half upward or downward (2 gestures). A sequence of these gestures forms a bend password. The iPod-touch-sized prototype is made from two types of silicone (softer at the bendable corners, firmer at the center to protect electronics), contains five bidirectional flex sensors, a vibration motor for haptic feedback when a gesture is recognized, and a push button for deleting or confirming input. It connects to an Arduino Leonardo microcontroller that maps gestures to keyboard entries on a connected computer.
Key findings
The prototype was iteratively developed with input from experts at the Canadian Council of the Blind, testing variations of material hardness, groove positioning, and groove depth across multiple versions. The grooves at each corner guide users to the bendable areas and were lengthened to span from side to side for effortless gesturing. The design uses two silicone types — softer Alumilite A30 at corners for easier bending and harder Alumilite A80 at the center for component protection. Prior research on bend passwords found them as easy to memorize as PINs but significantly harder to shoulder surf, since observers cannot easily discern the subtle physical deformations. Audio feedback names each recognized gesture (e.g., "Top right corner up") while haptic vibration confirms input without requiring visual attention. The keyboard mapping is invisible to the user, who only needs to remember a sequence of physical gestures. Beyond vision impairment, the authors identify potential applications for people with dexterity impairments (no precise item selection required) and learning disabilities (muscle memory for passwords), as well as eyes-free authentication for anyone.
Relevance
This work addresses an often-overlooked intersection of accessibility and security. While much accessibility research focuses on making content perceivable and interfaces operable, the security implications of accessibility features like screen readers are less frequently examined. The finding that standard accessibility accommodations actively compromise password security reveals a design tension that requires novel solutions rather than incremental improvements to existing methods. BendyPass demonstrates how deformable user interfaces — a relatively new interaction paradigm — can serve accessibility needs by shifting authentication from a visual channel to a tactile one. For practitioners, this highlights the importance of considering security as an accessibility requirement, not just a separate concern. The prototype's low cost and potential for Bluetooth pairing with existing devices suggests a practical path toward deployment, though user studies with people with vision impairments are still needed to validate learnability and memorability compared to PINs.
Tags: visual impairment · security · user authentication · deformable user interface · haptic feedback · shoulder surfing · prototyping