Sylvan Lobo
email: sylvan.lobo@tcs.com

Shyama V S Ulemba Hirom
email: ulemba.h@tcs.com

V S Shyama
email: shyamav.s@tcs.com

Mridul Basumatori
email: mridul.basumotari@tcs.com

Pankaj Doke
email: pankaj.doke@tcs.com

Coping with Accessibility Challenges for Security -A User Study with Blind Smartphone Users

Keywords: Usable Security, Blind, Smartphone, Android, iPhone

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Introduction

Smartphones are increasingly being adopted in India [1]. As an information device, a smartphone is very personal and portable compared to desktop computers and laptops.

Users tend to keep their phone with them at all times for a variety of personal information needs. It is always powered on and available on voice and data networks. This makes the smartphone attractive and vulnerable to security and privacy threats. There is a large population of visually impaired users, who are increasingly using touchscreen-based smartphones. Visually impaired users earlier used Symbian phones which were quite accessible with their assistive features and tangible keypads. Currently we observe that market forces seem to drive users to shift to touchscreen-based smartphones, primarily Android and iPhone. There has been considerable development [START_REF] Irvine | Tablet and Smartphone Accessibility Features in the Low Vision Rehabilitation[END_REF][START_REF] Kim | The interaction experiences of visually impaired people with assistive technology: A case study of smartphones[END_REF][START_REF] Robinson | Usage of Accessibility Options for the iPhone and iPad in a Visually Impaired Population[END_REF] in accessibility on these smartphone devices, both on iPhone and Android. Yet users still face usability challenges in certain situations where using the phone may be challenging (e.g. public transport, walking, crowded situations) [START_REF] Abdolrahmani | An Empirical Investigation of the Situationally-induced Impairments Experienced by Blind Mobile Device Users[END_REF] or simply due to unfamiliar or infrequently used interfaces. Considering the accessibility and usability challenges that visually impaired smartphone users face, we feel they are also more vulnerable with regards to privacy and security. E.g. using passwords and phone locks, or typing itself can be time consuming and error prone with currently available accessibility modes [START_REF] Azenkot | PassChords: Secure Multitouch Authentication for Blind People[END_REF]. Users also perceive privacy concerns while using accessibility modes [START_REF] Kane | Freedom to roam: a study of mobile device adoption and accessibility for people with visual and motor disabilities[END_REF].

The global visually impaired population is of a considerable size [START_REF]WHO: Global Data on Visual Impairments[END_REF], with around 5 million in India alone (some report 15 million) [START_REF]CENSUS OF INDIA 2011 DATA ON DISABILITY[END_REF][START_REF]IDA -India: Cataract Blindness Control Project[END_REF]. The World Health Organization (WHO) reported an estimate of 8 million people with total blindness [START_REF]Key Definitions of Statistical Terms -American Foundation for the Blind[END_REF] in India in 2010 [START_REF]WHO: Global Data on Visual Impairments[END_REF]. Mumbai, India, is reported to have a visually impaired population of around 0.12 million [START_REF]Data on Disability, Disabled Population by type of Disability, Age and Sex -C20 Table (India & States/UTs -District Level)[END_REF]. We found it imperative to include visually impaired smartphone users in smartphone security studies, to help understand threats that they may be exposed to and their current practices, eventually aiding in building better usable security for smartphones. For this study, we have only considered users with total blindness [START_REF] Boult | Revocable fingerprint biotokens: accuracy and security analysis[END_REF] users (rather than users with other visual impairment. As per American Foundation ® for Blind, total blindness refers to "an inability to see anything with either eye." [START_REF] Boult | Revocable fingerprint biotokens: accuracy and security analysis[END_REF]. We feel blind users would face such security and privacy risks and challenges more severely than sighted users and users with other visual impairments. Investigating these challenges would hopefully help in addressing concerns other visually impaired users too.

In this paper, we present the findings of our contextual inquiry based interviews with 51 totally blind smartphone users in Mumbai, India, with regards to their security and privacy practices with smartphones (Android and iPhone), their coping strategies with security measures such as passwords and native access control measures such as PIN, pattern locks and slide locks. We first review the relevant previous research, present the method used in our study and then highlight the outcomes of the affinity analysis of the contextual inquiry discussed from the perspective of security and usability, followed by a discussion of implications for design.

Previous research

There have been numerous studies with sighted users [START_REF] Leporini | Interacting with mobile devices via Voice-Over: usability and accessibility issues[END_REF][START_REF]IDA -India: Cataract Blindness Control Project[END_REF][START_REF]Key Definitions of Statistical Terms -American Foundation for the Blind[END_REF][START_REF] Chin | Measuring user confidence in smartphone security and privacy[END_REF][START_REF] Muslukhov | Understanding users' requirements for data protection in smartphones[END_REF][START_REF] Mylonas | Delegate the smartphone user? Security awareness in smartphone platforms[END_REF][START_REF] Tchakounté | Understanding of the Behaviour of Android Smartphone Users in Cameroon: Application of the Security[END_REF][START_REF] Ahmed | Privacy concerns and behaviors of people with visual impairments[END_REF][START_REF] Asokan | Usable mobile security[END_REF] as well as visually impaired users [1, [START_REF] Irvine | Tablet and Smartphone Accessibility Features in the Low Vision Rehabilitation[END_REF][START_REF] Robinson | Usage of Accessibility Options for the iPhone and iPad in a Visually Impaired Population[END_REF][START_REF]WHO: Global Data on Visual Impairments[END_REF][START_REF]CENSUS OF INDIA 2011 DATA ON DISABILITY[END_REF][START_REF] Muslukhov | Know your enemy: the risk of unauthorized access in smartphones by insiders[END_REF] with smartphones, laptops and internet on various aspects of usability, privacy and security, although we have not found relevant empirical studies with visually impaired or blind users in India with regards to their security and privacy practices and behavior with smartphones.

Mobile security studies with sighted smartphone users

Studies with sighted users suggest that users are generally concerned about privacy and security on their smartphones (even more so than on laptops). They are often signed in to multiple accounts on their phone, and use the phone to perform financial and other private transactions [START_REF] Leporini | Interacting with mobile devices via Voice-Over: usability and accessibility issues[END_REF][START_REF] Ahmed | Privacy concerns and behaviors of people with visual impairments[END_REF]. The indispensable, personal and highly portable nature of the smartphone demands that it be well protected from threats of data loss, compromise and privacy, including threats such as loss of phone due to damage, theft or misplacing; unauthorized access through malware or physical access; and location tracking [START_REF] Chin | Measuring user confidence in smartphone security and privacy[END_REF].

Asokan and Kuo [START_REF] Asokan | Usable mobile security[END_REF], Ben-Asher et al. [START_REF] Ben-Asher | On the need for different security methods on mobile phones[END_REF] and Jakobsson [START_REF] Jakobsson | Why mobile security is not like traditional security[END_REF], all argue that security approaches for mobile phone environments need to be revisited as the environment and usage differs markedly from traditional computers. Smartphones do provide some measures to mitigate risks [START_REF] Tchakounté | Understanding of the Behaviour of Android Smartphone Users in Cameroon: Application of the Security[END_REF], but the decisions are often delegated to the users themselves, who may not be sufficiently prepared or have the awareness to take correct decisions [START_REF] Mylonas | Delegate the smartphone user? Security awareness in smartphone platforms[END_REF]. However, studies suggest that users are not well informed about security and privacy decisions [START_REF] Tchakounté | Understanding of the Behaviour of Android Smartphone Users in Cameroon: Application of the Security[END_REF] and may often take inappropriate decisions. Users often do not find security features essential and keep them disabled [START_REF] Mylonas | Delegate the smartphone user? Security awareness in smartphone platforms[END_REF] [START_REF] Egelman | Are You Ready to Lock?[END_REF]. People also root or jailbreak their phones (Android and iPhone terminology to enable the phone for root or administrative access), leaving the phones vulnerable [START_REF] Mylonas | Delegate the smartphone user? Security awareness in smartphone platforms[END_REF]. Users avoid regularly upgrading the operating system, missing security patches. There are many apps available from non-official sources in the market places or app stores. In order to make decisions about installing apps, users tend to rely on the price (i.e. free or very cheap) and popularity based on recommendations from friends and user reviews, rather than studying the end user license agreements, privacy policies and app permissions [START_REF] Chin | Measuring user confidence in smartphone security and privacy[END_REF]. Users do not pay much attention nor comprehend the policies and app permissions [START_REF] Felt | Android Permissions: User Attention, Comprehension, and Behavior[END_REF]. Uses exhibit a 'click through' behavior when faced with various information prompts. Users trust the app repository with misconceptions that apps are tested for security [START_REF] Mylonas | Delegate the smartphone user? Security awareness in smartphone platforms[END_REF].

One common means of protecting information is using authentication means like passwords or phone locks. Yet many users do not use any phone locking mechanisms such as PINs or pattern locks simply due to usability issues and a need to access the phone quickly, despite the presence of private and sensitive content on the phone [START_REF] Muslukhov | Understanding users' requirements for data protection in smartphones[END_REF]. Users would rather keep the phone within sight at all times, without any password protection. This form of lock-based protection on phones provides an all-or-nothing access [START_REF] Karlson | Can i borrow your phone?: understanding concerns when sharing mobile phones[END_REF], and is quite risky considering passwords saved within apps are common [START_REF] Muslukhov | Understanding users' requirements for data protection in smartphones[END_REF] and users are not required to key-in passwords frequently. Users report that they use simple passwords such as names or dictionary words. Users also store their passwords on their phones as contacts in plain text [START_REF] Muslukhov | Understanding users' requirements for data protection in smartphones[END_REF].

Users consider data such as GPS tracking, SMS, Phonebook contacts, Multimedia content (such as videos, photos and recordings), emails, documents and notes as most private, valuable and sensitive [START_REF] Muslukhov | Understanding users' requirements for data protection in smartphones[END_REF]. They tend to not trust keeping private data in the cloud, and prefer storing data on their computers or hard disks unless the data is shareable [START_REF] Muslukhov | Understanding users' requirements for data protection in smartphones[END_REF]. People do share phones among themselves for music, entertainment and making calls, but would rather have the phone in sight and depend on their relationship with the other users. Users tend to consider it a higher threat to share phones with known people rather than with strangers [START_REF] Muslukhov | Understanding users' requirements for data protection in smartphones[END_REF]. Photographs and messages are kept private from known people and contacts private from strangers. Unauthorized access to the phone seems fairly common [START_REF] Muslukhov | Know your enemy: the risk of unauthorized access in smartphones by insiders[END_REF]. Chen et al [START_REF] Chen | Exploring Internet Security Perceptions and Practices in Urban Ghana[END_REF] also discuss Internet security practices of users in the context of users in a developing nation. Recent work by Alsaleh et al. [START_REF] Alsaleh | Smartphone users: Understanding how security mechanisms are perceived and new persuasive methods[END_REF] discusses smartphone security practices of users from the dimensions of behavioral change and provide persuasive approaches for addressing unsafe practices.

2.2

Mobile security studies with visually impaired smartphone users

Challenges of usability and accessibility enhance the security challenges faced by visually impaired users. Touchscreens lack tangible feedback, and users mostly depend on aural feedback or assistive devices (screen readers, zoom). There are various studies on security and privacy related aspects for visually impaired users [START_REF] Azenkot | PassChords: Secure Multitouch Authentication for Blind People[END_REF][START_REF] Ahmed | Privacy concerns and behaviors of people with visual impairments[END_REF][START_REF] Ashraf | Usability Issues of Smart Phone Applications: For Visually Challenged People[END_REF][START_REF] Dosono | I'm Stuck!": A Contextual Inquiry of People with Visual Impairments in Authentication[END_REF] and considerable advancement [START_REF] Irvine | Tablet and Smartphone Accessibility Features in the Low Vision Rehabilitation[END_REF][START_REF] Kim | The interaction experiences of visually impaired people with assistive technology: A case study of smartphones[END_REF][START_REF] Robinson | Usage of Accessibility Options for the iPhone and iPad in a Visually Impaired Population[END_REF] in accessibility on touchscreen . Commonly performed activities on smartphones (and computers) include reading and writing emails, browsing internet for entertainment, downloading/uploading files, education, listening to podcasts, instant messaging, and interacting on social media platforms [START_REF] Inan | Internet Use and Cybersecurity Concerns of Individuals with Visual Impairments[END_REF]. Users also transact and bank online, but usually prefer using desktops and laptops over smartphones.

Azenkot et al. [START_REF] Azenkot | PassChords: Secure Multitouch Authentication for Blind People[END_REF] found that visually impaired users are generally not aware or concerned about security, and often use their phones without password protection primarily due to inconveniences faced. For example, the phone allows passwords to be masked, i.e. the screen reader reads the characters as stars or clicks while the user types in the password. This however makes it near impossible for users to type, i.e. without text entry feedback on a touchscreen device, users are clueless about what they are typing. If the user chooses to not mask the passwords, the screen reader speaks the characters aloud, which is again not desirable for keeping the password private. Users also find password managers, password recovery mechanisms, and typing itself quite difficult [START_REF] Ahmed | Privacy concerns and behaviors of people with visual impairments[END_REF]. Users often tend to store their password elsewhere written in Braille or in files, or save them within apps [START_REF] Ahmed | Privacy concerns and behaviors of people with visual impairments[END_REF].

There is also a lack of sufficient feedback while browsing the Internet or using smartphones, using the assistive features available. Some users hence spend less time online [START_REF] Inan | Internet Use and Cybersecurity Concerns of Individuals with Visual Impairments[END_REF]. For instance, browser do not highlight phishing in an easily accessible manner, and feedback about errors is poor. Often user interfaces change frequently [START_REF] Ahmed | Privacy concerns and behaviors of people with visual impairments[END_REF], which means the user needs to learn how to use the interface again.

In terms of privacy, visually impaired users frequently face the risk of being eavesdropped, both aurally and visually, in almost all activities they perform on the phone as they are often not sure when people are in their vicinity [START_REF] Ahmed | Privacy concerns and behaviors of people with visual impairments[END_REF]. They feel a lack of independence and have to rely on sighted users for assistance, often strangers where they need to disclose private information in various situations such as filling forms, or reading messages or letters. Some users hence prefer online transactions and online shopping over shopping in real stores, although they still have concerns of security [START_REF] Ahmed | Privacy concerns and behaviors of people with visual impairments[END_REF]. Users have various strategies to maintain privacy like relying on close relations such as spouse, family or close friends; using assistive technology; using screen curtains to black out the display; using headphones; or using the screen reader at low volume or at a very fast talking rate where others would find it difficult to understand.

As seen in the background literature, visually impaired users as well as sighted users face quite a few security and privacy challenges with their smartphones. They risk and often fail to protect their data effectively. The lack of awareness and inconvenience due to which users do not take appropriate measures can be attributed to usability and accessibility issues in interfaces and mechanisms provided for achieving the goals of security and privacy. The security goals in themselves are not primary, although a single event of compromise of data or privacy can prove disastrous to users. The phone is shipped with security features but in the context of the user they are not usable.

Usability and security

Usability can be defined as the: "extent to which a system, product or service can be used by specified users to achieve specified goals with effectiveness, efficiency and satisfaction in a specified context of use." (ISO 9241 210:2010) [START_REF] Bevan | ISO 9241-11 revised: What have we learnt about usability since 1998?[END_REF]34].

Products are generally created with goals of usability. There are various methods to assess usability such as Nielsen's [START_REF]10 Heuristics for User Interface Design[END_REF] usability heuristics or Joshi's [START_REF] Joshi | Usability goals setting tool[END_REF][START_REF] Joshi | Do Teams Achieve Usability Goals? Evaluating Goal Achievement with Usability Goals Setting Tool[END_REF] Usability Goals Tool (UGT). Usability goals could include: ease of use where the conceptual model is communicated clearly so that there is a match between users' mental model and the product, without entry barriers and unnecessary tasks, minimizing user task load, and always accessible. Operation of the product should be error-free, should not induce errors and the user should be able to recover easily if and when errors do occur. The system should provide appropriate feedback, display current status and should be accessible at all times.

While security is another overarching and important goal, users might take it for granted or consider it coming in the way of their actual goals. So, when usability and security intersect there are additional considerations and methods for usability evaluation [START_REF] Saltzer | The protection of information in computer systems[END_REF][START_REF] Whitten | Making security usable[END_REF][START_REF] Whitten | Why Johnny Can't Encrypt: A Usability Evaluation of PGP 5.0[END_REF]. Saltzer proposes design principles for data protection among which the following seem relevant for when intersected with usability: "economy of mechanism" where the design is to be as simple and small as possible; "fail-safe defaults" and "psychological acceptability".

Whitten defines security software as usable, through four points as follows: "Security software is usable if the people who are expected to use it: 1. are reliably made aware of the security tasks they need to perform; 2. are able to figure out how to successfully perform those tasks; 3. don't make dangerous errors; and 4. are sufficiently comfortable with the interface to continue using it." [START_REF] Whitten | Why Johnny Can't Encrypt: A Usability Evaluation of PGP 5.0[END_REF] Whitten describes properties of security which make it difficult to get user interfaces right or usable, such as: "unmotivated user", "abstraction", "lack of feedback", "barn door principle", and "weakest link". The unmotivated user property highlights that security is not the primary goal of the user. Instead, the user wants to achieve other tasks, and would easily not give much thought to security, assuming that they are safe. Abstraction refers to abstracted security rules for granting access which may not seem intuitive to most users. The lack of feedback property speaks about how it is difficult for security software to perform useful error checking and provide feedback that the user wants. The barn door property refers to leaving secrets accidently open, after which one can never be sure if any attacker might have accessed it or not. The weakest link property refers to security being strongest as the weakest component, which can be exploited by attackers. User interfaces for security places priority on ensuring that users understand security well enough, and they should be guided through all aspects [START_REF] Whitten | Why Johnny Can't Encrypt: A Usability Evaluation of PGP 5.0[END_REF].

We have considered these dimensions of usability and security as per Joshi et al. [START_REF] Joshi | Usability goals setting tool[END_REF][START_REF] Joshi | Do Teams Achieve Usability Goals? Evaluating Goal Achievement with Usability Goals Setting Tool[END_REF], Whitten [START_REF] Whitten | Making security usable[END_REF][START_REF] Whitten | Why Johnny Can't Encrypt: A Usability Evaluation of PGP 5.0[END_REF] and Saltzer [START_REF] Saltzer | The protection of information in computer systems[END_REF] in our analysis and discussion of our findings.

Method

The objective of this study was to gain insights into how total-blind [START_REF]Key Definitions of Statistical Terms -American Foundation for the Blind[END_REF] users used touchscreen-based smartphones, with a focus on privacy and information security issues they faced, their coping strategies and practices, and their conceptual models.

We interviewed 51 total blind smartphone users in Mumbai, India, using a Contextual Inquiry (CI) [START_REF] Beyer | Contextual design: defining customer-centered systems[END_REF] approach. We chose to interview total blind and not users with other forms of visual impairments to have a homogenous group of users, assisting our analysis of responses and cause of their behavior and practices. The users were in the age group of 18 to 40 (averaging around 25 years). There were 36 male and 15 female participants. More detail about the participants is provided in the table 1 below. A group of researchers individually visited users at their homes, colleges or workplaces, across Mumbai. The CI method recommends visiting the users in their context. The researchers first briefed the users about the study, sought consent and proceeded with the interview. The researchers simultaneously also noted observations about the user and their immediate environment. The researchers gathered basic information from the users such as their demographic details, phone models and prior experience with smartphones, and then gradually proceeded towards asking contextual questions focusing on their security practices with the smartphone. The interviews had a conversational format and the researchers played the role of an 'apprentice', where the user would demonstrate how they used certain security related features on their phones with as much detail as possible (e.g., how they set a phone lock, or how they unlocked their phone). The users were also nudged to retrospectively recite various security related situations they might have been in, and were probed to provide details. As far as possible, the researchers avoided speculative situations and relied on past situations which the user actually had been in.

The interviews primarily dwelled on the usability and security related practices and challenges blind users faced in their daily livesi.e. beliefs, practices and challenges they faced with using the locking mechanisms, with setting locks, managing Privacy, and setting, managing and using Passwords for their online accounts and apps.

The interviews were recorded using voice recorders, and later transcribed where local language were not translated. The interviews were discussed for arriving at structured notes. The researchers read and familiarized themselves with the interview transcripts, photos and videos, and shortlisted notes that were particularly related to the focus on Smartphone Usability and Security for blind users. The notes were printed as paper chits which were shuffled around in a box. Researchers picked a chit from the box, read it out aloud or passed it around. From a discussion that ensued the researchers arrived at a consensus about a model explaining the observation in the note, and noted down the model on a Post-It™ note. The Post-It™ note was put on a table with the chit below it. The researchers continued picking up chits from the box, and arrived at more models or updated existing models on the table, till clusters and categories formed.

Once all notes were categorized, the researchers then identified key categories which had a larger number of chits and seemed highly relevant to our focus, or were novel. The researchers read through the chits one by one under that category and tried explaining it through a model which was written or sketched on Post-It™ notes on a wall. With every chit we either reclassified it with other categories on the table if appropriate or updated the model on the wall till a good understanding of observed phenomena emerged and was captured through models on the wall. To illustrate with an example: We clustered notes with observations such as how users used Talkback at low volumes, or at very fast rates, or strategies such as touching additional 'fake' characters while entering passwords to confuse eavesdroppers. These observations led us to arrive at models such as 'Obscurity is used as a means to achieve privacy'. Such models after subsequent structuring, also developed into a primary category -'Assistive software is used as a layer of security', which we discuss later in section 4.3. In this way most of the categories and chits on the table were analyzed till we arrived at the most novel or relevant themes, in the views of the researchers, as described in the following sections. Fig. 1 showcases the affinity diagramming. Users expressed that virtual keypads were more difficult to use as compared to the Symbian based tangible keypad phones that they used earlier. Tangible keypads allowed speed and accuracy in typing as it was easy to find the correct keys. With touchscreen phones however, despite accessibility software such as Talkback or Voiceover, it is a challenge to locate keys accurately without the tangible feedback. Users often face breakdowns by accidentally pressing wrong keys or activating undesired operations. For instance, text entry usually involves three taps: one for scanning and reading out the letters on the keypad followed by a double-tap to enter the last key that was spoken out (there may be other such similar techniques). This is much slower than the tangible keypads where users could find and enter the desired keys easily, simply relying on their cognitive and muscle memory of the location of the key. With phone locks, issues are amplified as the users' desire frequent and quick access to their phones, and the lock gets in the way. Hence we found users opting out of locks or using very simpleto-type PINs and Patterns.

"…the screen reader speaks numbers and symbols, but at times we accidently press the small button the side which changes the language… We don't understand what's happening then, and we have to re-enter the password." -(NJ.U4.06) 1

Our observations led us to believe that the typing difficulty on virtual keypads led users to keep passwords that are easier to type, which are also hence predictablethose which would have minimal resistance or ease of entry. We thus observe a conscious move towards predictability to lower the entry barrier, indicating that the user goals significantly outweigh behavior towards protection interventions. E.g., User AS03 (Fig. 2) demonstrated how they entered 111111 as a PIN on her iPhone. It simply required her to first scan and locate 1 (which was easy). After that they had to double tap multiple [START_REF]IDA -India: Cataract Blindness Control Project[END_REF] times to enter six 1's, which they did quite rapidly. We thus observe that the coping mechanisms deployed by the users significantly increases risk of compromise.

"It's better to keep a single digit. I've kept 1 six times." -(AS03)

Consider an alternate example, 135743. This would require the user to scan and locate each digit followed by a double tap, which is an increase in 5 taps, slowing the user. 111111 reduces the effort required to scan, locate digits and double tap. Users may not keep PINs that require them to move all over the keypad. A similar practice was noticed with using Patterns, where they resorted to starting at edges and preferring straight lines (L's) or squares.

1 Note: All quotes are translated into English from Marathi and Hindi, for international readers. "One sleeping line goes over 3 points and one standing line goes over 2 points. I felt this is possible for blind people. I tried a lot, to at least make one sleeping line…on my phone as well on others, but I couldn't figure it out. There are just 3 sleeping lines, but it is difficult. If there was only one sleeping line, then it could help blind people." -(SKU412) Fig. 2. User sets a PIN using a single digit It appears that users focus on ease and speed of input for passwords and locking mechanisms, rather than recallability or non-guessability, when using touchscreen devices. If users perceive access control measures as reducing productivity, they deploy weaker protection measures which are predictable based on ease of entry. A related observation about predictability of passwords, was that users kept simple and recallable passwords based on their daily personal contextual data, or rather based on their 'signup' information. By this we mean that passwords were combinations of details such phone numbers, account numbers, names of friends, family or places, or names of favourite movies and games, or related to religion or beliefs (such as names of gods, or lucky numbers). This is not very different from what one would expect with sighted users' passwords. The users however did demonstrate attempts to mix and combine names, numbers and characters to try keeping the passwords non-guessable.

"For Facebook, I've kept my password close to my name. In Gmail I have tweaked my phone number a little here and there. So that I don't forget." -(BBU215)

The other specific finding about password choices with blind users was that visually impaired users have a unique code for representing letters by number codes. E.g. User DTU6 encoded their passwords using this strategy, which could be a decent technique for setting a recallable password which is non-guessable at least outside the community.

"Actually, we speak a number language, which we call 123… I had just kept my name (as password)…in Marathi -C means Cha. We call C (Cha) as 31. So, I had kept the password like 31 ** ** 12 (masked for privacy)." -(DTU614)

Literature highlights how the keyboard layouts and small form-factor of mobiles affect influence password choices [START_REF] Genco | Alternative Keyboard Layouts for Improved Password Entry and Creation on Mobile Devices[END_REF][START_REF] Von Zezschwitz | Honey, I shrunk the keys: influences of mobile devices on password composition and authentication performance[END_REF]. Our observations suggests that accessibility of the touchscreen interfaces also affects the password choices both in case on PINs as well as Patterns.

Migration across locking mechanisms -No lock to TouchID

Fig. 3 below highlights how we interpreted users' transition across various locking mechanisms, based on three dimensionssecurity, usability and accessibility. Users tend to start out with no phone locks when the phone is new, and might use the Swipe/Slide Lock or simply the power button to start the screen. Users commonly stated that there is nothing valuable on their phones to justify the absence of locks. They felt locks prevented hassle-free frequent access to their phones. They also feared getting locked out of their phones, in case they forgot the password. One user also believed that passwords would slow down the phone. Some users stated that they did not know how to or had not yet 'learnt' how to set the phone locks and might do so at some later point in time. Some users reported that in case of emergencies, others should be able to use and unlock their phones. They stick to the adopted mechanism (beginning with no-lock as in Fig. 3) till a trigger makes them change and adopt locks. These triggers are either from the dimension of security, usability or accessibility issues. The security trigger is usually an exposure to a risk situation where they may have lost data, faced privacy issues, etc. This prompts users to start employing a security measure, usually a PIN lock. Other reasons could be merely out of curiosity, e.g. trying out Patterns as it appears as an interesting challenge to blind users. Once they have adopted a security measure, again users would stick to it till they feel inconvenienced by usability or accessibility challenges with the mechanism, prompting them to try out other mechanisms or revert to no locks (or easier mechanisms like PINs). In case of biometric fingerprint based locks (Touch-ID on iPhones), we felt users did not revert to other mechanisms. (We did not observe users of biometric fingerprint locks on Android phones). This migration might take place till users find a good enough balance between accessibility, usability and security.

"…Once, a family member met with a bike accident. Their phone was locked completely. No one was able to call the family members as the app lock couldn't be unlocked. That's one reason (for not keeping a lock.)" -(BBU716)

Users seem to need a strong trigger to begin using phone locks. These are often cases of thefts, shoulder surfing and being unable to assess if anyone is watching their screens, or sensitive information/applications such as net banking installed on the phone. Similar triggers also led users to change their current PINs (or passwords). Users explored the various security phone locking options and usually settled on PINs stating that numbers are easy and less tedious compared to Passwords or Patterns. Patterns were treated as impossible to understand for blind users. iPhone users however loved the biometric fingerprint option -TouchID.

"I had a friend sitting near me, who saw me opening my phone lock. She asked me for my password. I refused, but she was insistent. Then she said she knows my password. I told her to open my phone then if she could. She unlocked it! She was partially (blind) so she could see. I immediately changed the password." -(RCU4)

Some users either preferred PINs over Patterns or Patterns over Pins due to perceptions about how they performed on speed and ease, especially during situations/context where the mechanism were difficult to usesuch as being sleepy or travelling in public transport where the rides are bumpy.

"The problem with PIN was you had to double touch every time. I had kept mine (password) as 1234. So you have to type double 1, double 2 double 3, double 4 due to talkback. Talkback requires double touch. Sometimes when I'm on the road, I face difficulties. Then I changed to a Pattern. Since then my problems have reduced, because with this I can open my phone quickly." -(BBU210)

iPhone users found the fingerprint biometric authentication -Touch-ID, as a very convenient option, despite occasional issues faced in fingerprint recognition. Users who used Touch-ID would not migrate back to no locks. They felt comfort with the presence of a fallback of a PIN when fingerprint recognition failed, so they did not have the fear of getting locked out of the phone. Most other (Android) users either used PINs or reverted to the swipe lock, or no lock or interestingly used accessibility features, such as Dim-Screen as a layer of security (discussed in the next section).

"Basically I use TouchID. I also have Passcode in place. The TouchID has a good biometric sensor, it works most of the time. When it doesn't, then I use Passcode. I believe TouchID is the best, you know you need to place the thumb." -(BBU105)

Existing studies [START_REF] Azenkot | PassChords: Secure Multitouch Authentication for Blind People[END_REF][START_REF] Egelman | Are You Ready to Lock?[END_REF][START_REF] Harbach | The Anatomy of Smartphone Unlocking: A Field Study of Android Lock Screens[END_REF] have found that most users (sighted) use locks for security and privacy, with PINs being prevalent. For those who do not use locks, it is usually due to a lack of motivation, lack of concern or inconvenience. Users tend to start using locks when prompted to (usually by a significant other) and would then stick to using the lock, despite inconveniences faced. Users seem to face more errors with Patterns, compared to PINS. Azenkot in an earlier study with visually impaired users found all their participants avoided lock, which is not the case in our study, but those who did not use locks claimed similar reasons of not knowing about it or inconveniences faced. Similarly, the use of Screen Curtain instead of a lock was prevalent in our study too. Users in our study however claimed avoiding headphones in public, contrary to Azenkot's observation. While the studies have discussed users' motivations to use locks, their choices of pass-codes, and also compared common options such as PINS, Patterns and Biometrics, further investigation of how people choose and migrate between various forms of locks might yield interesting insights, especially concerning usability and accessibility of the interfaces with visually impaired users.

Assistive software as a layer of security

Users may not always find the existing accessibility features on their phone to effectively use the locking and security mechanisms effectively. For instance, the screen readers read the passwords aloud while entering passwords. There are settings where users can disable the screed reader from reading the passwords, but then they do not know what they are typing. This leaves them with the option of using headphones which is not suitable for frequent unlocking, and hence is a discomfort. Users also feel headphones are unsafe to use constantly as they depend on their aural senses for their activities. Users face issues of accuracy and speed with using the unlocking mechanisms as discussed in section 4.1. Users tend to deal with these situations by doing away with phone locks altogether, or entering the code at low volume without headphones.

"A long time back I had tried passcode, but it used to just say dot-dot when I would enter any number. I could not know what number was pressed. That's why I never set anything for screen lock." -(ASU501)

Instead of depending on the locking mechanisms alone, users seem to also use the assistive features as an additional layer for security. For instance, when users are unable to assess if anyone is eavesdropping, then tend to obscure or hide their activity using physical means, i.e. holding the phone in a particular way or covering the screen with their hand. Another interesting way of obscuring was using the accessibility options on the phone, i.e. the Dim Screen or Screen Curtain option, or the screen reader set at a very fast speaking rate. With the Dim Screen option, the screen is totally turned off while operating so others are unable to see the screen. Hence users also went to the extent of not using a phone lock, as they felt Dim Screen was sufficient protection from snoopers.

"I use a feature present in TalkBack, called Dim Screen, so I don't need to keep any password. Nobody can see anything. Because of this feature I do not require any screen security for my phone." -(NSU215, [START_REF] Egelman | Are You Ready to Lock?[END_REF] Again, the screen reader and other alternate gestures that they used when the phone is in accessibility mode were considered difficult for others, mainly sighted users. Hence they felt their phones were safe from others. They felt other users need to be skilled to use the phone with the accessibility mode on. They also kept the speech rate very high, making the speech indiscernible by others. This was another form of obscurity protecting their privacy in public. In the case where the screen readers speak the password/pin aloud, one user intentionally scanned over random keys while entering the password, thus obscuring the actual password. Although not fool proof, an untrained listener would find it difficult to understand which keys were merely scanned and which were actually entered.

"If I don't want people to know what my PIN is, I create a false PIN by touching extra numbers. If I don't release the touched numbers, they are not entered. So people do not know what PIN I entered. Generally, I keep in mind that when I enter my PIN, I hold my phone closer to me so that nobody can see anything. Even you didn't get my PIN, did you?" -(BBU108)

In some cases users felt that keeping the screen reader at a very loud is useful, especially when the phone is not on their person. This allowed them to notice if somebody started interfering with their phone.

However, it is apparent that these approaches of depending on accessibility features for obscurity for privacy and protection is limited. It only protects them from sighted and untrained users. As the phone security features are not amenable out-of-the-box to the blind users, the users have coped up by using assistive features in interesting ways. We feel that it might be interesting and useful if designers could explore this further and consider enhancing assistive features for security and privacy too. While studies have highlighted the use of Screen Curtain for privacy [START_REF] Azenkot | PassChords: Secure Multitouch Authentication for Blind People[END_REF], the phenomenon and opportunity of adapting assistive software of smartphones of security and privacy would be interesting to explore further.

Patternsa maze

Most users felt Patterns are impossible for them to use as they cannot understand them. They face difficulty in locating the dots and connecting them by gestures (lines). Patterns are not accessible enough although there are soft buzzes when the user touches the dots. The screen reader also provides a few instructions, but are mostly not helpful enough. Some users had explored patterns but did not adopt them as were unable to use them, despite feeling that Patterns could be faster to use than PINS. We feel users found it challenging to build a mental model of Patterns. It was also a new mechanism which was not available on earlier tangible phones.

"It would just speak 'Pattern Area'. I would draw the wrong pattern. The phone would never unlock. I had to take somebody else's help. So, I stopped using patterns." -(SKU409)

We found a couple of users who used patterns easily. We observed that user BBU2 had developed a strategy to locate the first dot, after which they could locate the rest and reach a speed similar to sighted users in unlocking the phone. The user held the phone in a unique way with the thumb and fingers positioned possibly to locate the first dot accurately, i.e. on the right top edge of the pattern grid (Fig. 4). However, we noticed that the few users who used Patterns appeared to use quite predictable patterns to enable accurate and quick access. The tendency was to start at edges, as they needed an anchoring point. They relied on straight paths and avoided diagonals, to avoid accidentally touching the wrong dots. This resulted in simple shapes -'sleeping lines' or L's, and squares (a C) on the 3x3 grid. Similar to the concerns people had with PINS, users also found using Patterns accurately in certain situations where attention is difficult (e.g. sleepy or travelling).

"…I would want to connect four dots only. I don't want to connect more. So, I'm telling you that I would keep an L or Square." -(BBU215) Despite its apparent difficulty, Patterns could be widely adopted by blind users if the accessibility was improved. Example, it should be easier to locate and anchor to the starting dot in the pattern. E.g. Buzzi et al. have discussed approaches how visually challenges users can orient themselves on touchscreens more easily [START_REF] Buzzi | Vibro-tactile enrichment improves blind user interaction with mobile touchscreens[END_REF][START_REF] Buzzi | Haptic Reference Cues to Support the Exploration of Touchscreen Mobile Devices by Blind Users[END_REF]. Otherwise, for most users the Patterns is currently a mazethey need to be really motivated to attempt to understand and develop a strategy to find their way through. Existing studies [START_REF] Andriotis | A pilot study on the security of pattern screen-lock methods and soft side channel attacks[END_REF][START_REF] Loge | On User Choice for Android Unlock Patterns[END_REF][START_REF] Von Zezschwitz | Patterns in the wild: a field study of the usability of pattern and pin-based authentication on mobile devices[END_REF] are inconclusive about preferences of Patterns over PINs. Patterns seem to have a higher rate of errors. Yet users tend to prefer Patterns as they perceive better feedback, ease of use, efficiency and memorability. We were unable to find detailed studies discussing the use and accessibility of Patterns by visually impaired users. Users seem to need to orient themselves better on the screen to be able to use Patterns more effectively.

Password backups and fallback users

Users frequently seek assistance from others, usually sighted users, to set up their online accounts for email, Facebook, etc. They often require assistance as they are unfamiliar with the interface, and also find CAPTCHAs challenging. They usually seek assistance from people they consider tech-savvye.g. trainers as blind institutions, phone vendors, or family members. While seeking assistance, they often share personal information including passwords. Some users reported that they did not change the passwords later, as they trusted the person who helped them and expected him or her to forget about it. However, some users who appeared more tech-savvy and security paranoid did change the passwords later. Some even deleted their account and set up a new account as they were now familiar with the process. "I had faced a problem with my Gmail account. I had entered username properly, but when I tried to enter password, it would speak out star-star… I didn't know what to do. Then I took a sighted person's help for logging in using email id and password" -(ASU101)

Users face similar challenges in resetting passwords, and need assistance. To prevent forgetting passwords, especially important ones, users resort to sharing passwords with a trusted person, as a backup. This trusted person is usually a family member or a close friend, who may also sometimes assist the user with operating the account. Sharing passwords is also seen in an existing study by Singh et al. [START_REF] Singh | Password Sharing: Implications for Security Design Based on Social Practice[END_REF] an emerging trend, especially among married couples, disabled users and indigenous communities. The authors [START_REF] Singh | Password Sharing: Implications for Security Design Based on Social Practice[END_REF] also highlight principles for Design considering such a phenomenon.

"My friend knows my password because he needs it to fill some forms for me. He is the only person who knows my password." -(RSU412)

They also resort to keeping the password written down in a diary at home or in a password-protected file on their laptop. Users also maintained a list of passwords that they cycled through across various accounts. Other users however relied on using the "forgot password" option to reset the password instead of taking measures to remember, store or share passwords. Some used drastic measures such as creating a new account, rather than attempting recovery. Similar reactions are reported in a study with lessliterate users [START_REF] Doke | A User Study About Security Practices of Less-Literate Smartphone Users[END_REF].

The motivation to share or store passwords seems to stem from the difficulty faced in recalling passwords as well as in resetting their passwords. The passwords that were shared or backed up were usually those that were important and infrequently used (e.g. those related to the college/university or banking).

"My university password… I've written it in 2-3 places. It is written on my mobile, at home, and on my wall calendar as well." -(RSU714) Table 2 provides a summary of number of notes considered supporting the themes that emerged.

Discussion and Design Recommendations

We assessed our findings using the framework of UGT [START_REF] Joshi | Usability goals setting tool[END_REF][START_REF] Joshi | Do Teams Achieve Usability Goals? Evaluating Goal Achievement with Usability Goals Setting Tool[END_REF] to define the users' usability goals and also considered usable security related aspects from Whitten [START_REF] Whitten | Making security usable[END_REF] and Saltzer [START_REF] Saltzer | The protection of information in computer systems[END_REF]. We considered the usability and security goals for blind smartphone users as 1) being able to protect their data and privacy using the security mechanisms on their phone appropriately, 2) being able to protect their online accounts with good password practices supported by the phone interfaces. Users tend to find existing phone locking mechanisms error-prone due to lack of tangibility and ineffective feedback, affecting accuracy, speed and ease of use. Although users are often motivated to learn the locking mechanisms, apparent from how they have explored the various options, they often find it difficult to understand the mechanisms and are not comfortable with the interfaces. Users also face barriers in locating and learning the settings for setting up the locks, especially without assistance from sighted users. This activity of setting a lock is infrequent, and being unfamiliar with the interface, users tend to have a certain amount of fear to set up locks. Frequent errors while using the locks also lead to the fear of getting locked out of their own phone ('dangerous errors'). Tapping on areas accidentally also messes up the interaction (Economy of mechanism' and 'Psychological acceptability'). Hence, users either opt to not using locks at all, or adopt very simplistic predictable passwords ('unmotivated user'). Additionally they adopt accessibility features as means to obscure and protect privacy. Accessibility concerns seem to be the key issue that affects secure adoption of phone locks by blind users. Improved accessibility and biometric approaches could improve adoption. Among the locking mechanisms available, finger print recognition seems to have the best 'economy of mechanism' and 'psychological acceptability'. However, it can be argued that biometric authentication still needs to evolve for better security [START_REF] Boult | Revocable fingerprint biotokens: accuracy and security analysis[END_REF]. Patterns is another promising quick approach, if accessibility could be improved. Poor accessibility also leads the user to take assistance from othersblind and sighted ('weakest link', 'barn door'). They even write and sharing their passwords or accounts, leaving themselves exposed and vulnerable to attacks. Hence, improving the accessibility of especially of security features is of prime importance.

We also found that the users have an attitude of continual learning and have a closeknit community among themselves. They are informed about good practices and share tips among themselves via workshops conducted by organizations for blind or via WhatsApp and other online communities. As users seem open to technology and share information and good practices, we feel quick dissemination of security solutions and awareness is possible. Being tech savvy and explorative, alternative interfaces could be explored which might be usable and effective to visually impaired users. Researchers such as Kane, Leporini, Buzzi, Azenkot and Guerreiro have discussed novel approaches for usable and accessible interfaces on smartphones [START_REF] Buzzi | Haptic Reference Cues to Support the Exploration of Touchscreen Mobile Devices by Blind Users[END_REF][START_REF] Azenkot | Input finger detection for nonvisual touch screen text entry in Perkinput[END_REF][START_REF] Buzzi | Playing with geometry: a Multimodal Android App for Blind Children[END_REF][START_REF] Buzzi | Designing a text entry multimodal keypad for blind users of touchscreen mobile phones[END_REF][START_REF] Guerreiro | From tapping to touching: Making touch screens accessible to blind users[END_REF][START_REF] Kane | Slide Rule: Making Mobile Touch Screens Accessible to Blind People Using Multi-touch Interaction Techniques[END_REF][START_REF] Kane | Access Overlays: Improving Non-visual Access to Large Touch Screens for Blind Users[END_REF].

A primary challenge with visually impaired users using touchscreen smartphone interfaces is the lack of tangibility and visual cues. Sighted users usually rely on subtle or direct visual cues while interacting with user interfaces. This channel is blocked out for blind users. Instead they depend on the audio channel, which is either missing or minimal, and is usually incidental and not specifically designed for accessibility. At the most there is minimal haptic feedback through buzzes, and the screen reader but does not provide a sense of a user interface that visual cues do. In current interfaces, there seems to be little or no mapping or information redundancy between the visual and audio channels. A transfer of feedback from the visual to an aural and tangible channel is required for appropriate feedback as recommended for usability of the interfaces. Users could then subconsciously process information while interacting with the interface. Such interfaces could be translated to have a parallel aural and haptic interface. For instance a Morse-like code which vibrates privately in the hand. Vibration and aural standards could be defined as alternatives to visual interfaces, over and above screen reader which are essentially text to speech. For example, some existing studies investigate providing prosodic cues with screen readers [START_REF] Murphy | Designing auditory cues to enhance spoken mathematics for visually impaired users[END_REF][START_REF] Pitt | Improving the usability of speech-based interfaces for blind users[END_REF].

Accessible security interfaces should focus on achieving better speed and ease-ofuse. Occasionally used screens such as Settings or Account creation should be accessible enough to avoid assistance from sighted usersor at least designed to allow mediation and assistance but maintaining privacy of the users wherever required.

New accessible phone locks can be exploredagain focusing on ease and speed of use for visually impaired or eyes-free access. For existing phone locks, fallbacks could be introduced: e.g. Touch-ID to PIN. Instead of locking out phones after unsuccessful attempts to unlock the phones (caused by errors in input), users could be given a secondary lock interface. Anchoring points could be developed or overlaid on touch screens (as in the mark on the '5'-key on earlier phones) which could assist users to orient and anchor themselves to use visual/spatial interfaces such as PINS. There is scope for the pattern locks to be improved for accessibility. Potentially, there are a lot of cues from the earlier tangible Symbian phones, and how blind users used them, which could transition into the newer touchscreen smartphones.

Users currently use the accessibility settings for privacy, such as a rapidly speaking screen reader or dim screen. The accessibility features could be enhanced to embrace this behaviour, and designed for better obscurity, allowing privacy from blind and sighted users alike.

Conclusions

We believe that the area of security interventions for smartphones in the context of usability can be better aligned. Users face constant difficulties due to accessibility shortcomings. This affects their productivity and they opt out of using locking mechanisms. They cope up by appropriating the assistive features as obscurity for privacy. Improvement in the accessible phone locks, password recovery and account creation, could vastly assist them being independent and secure.

Fig. 1 .

 1 Fig. 1. Affinity Diagramming

Findings

Fig. 3 .

 3 Fig. 3. Migration across phone locking mechanisms

Fig. 4 .

 4 Fig. 4. User using a Pattern lock accurately identifying the dots

Table 1 .

 1 Particpants details

		Female	Male	All
	Number of participants	15	36	51
	Average Age	25	25	25
	18 to 20 years	3	8	11
	21 to 25 years	6	16	22
	26 to 30 years	4	7	11
	31 to 35 years	2	3	5
	36 to 40 years	0	2	2
	Number of Android Users	12	32	44
	Number of iPhone Users	3	4	7
	Number of Employed participants	9	13	22
	Students	5	22	27
	Unemployed	1	1	2

Table 2 .

 2 Key themes and supporting notes considered

	Key themes	Supporting
		notes considered
	Accessibility challenges lead to predictable passwords	82
	Migration across locking mechanisms	97
	Assistive software as a layer of security	42
	Patterns -a maze	27
	Password backups and fallback users	34

Acknowledgments. We thank all the users, volunteers, and all publication support and staff, especially the reviewers who wrote and provided helpful comments on versions of this document. We thank Interact for supporting and improving our paper through its shepherding process.


Michaela Riganova

Jan Balata

Zdenek Mikovec

Crowdsourcing of Accessibility Attributes on Sidewalk-Based Geodatabase

de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

According to Sammer et al. [START_REF] Sammer | Identification of mobility-impaired persons and analysis of their travel behavior and needs[END_REF], almost 16 % of the population is limited in mobility, namely visually impaired, hearing impaired, wheelchair users, and people with impaired ability to walk. Appropriate navigation system considering sidewalks and their accessibility attributes can help significantly. However, current navigation systems are created for cars, thus ignoring sidewalks, crosswalks, landmark information and important accessibility attributes.

To address this issue, we designed a sidewalk-based geodatabase1 (Geographical Information System -GIS) with the following features: line features tied to large part of the pedestrian segment (a sidewalk, a crosswalk, an underpass) with attributes (sidewalk slope, material, light signalization, traffic noise); point features tied to short part of the pedestrian segment that acts as a barrier (a staircase, obstacle) or a landmark (corner, recess) with attributes (corner shape, number of steps, unobstructed width).

The GIS is created in two phases: 1) Pedestrian segments with line and point features are drawn into the GIS by a professional using resources such as satellite imaging, a "map of town utilities," creating a template for the second phase. 2) The template is filled in with attributes assigned to the features via professional "on-site reconnaissance," which is highly labor demanding. The features and their attributes were carefully designed and selected in cooperation with orientation and mobility specialists. The GIS enabled us, for example, to generate landmark-enhanced itineraries for blind pedestrians [START_REF] Balata | Automatically generated landmark-enhanced navigation instructions for blind pedestrians[END_REF].

Our aim is to design a mobile application for collection of pedestrian attributes of segment features in the field using crowdsourcing. The non-experts will fill the data in the professionally created template of the GIS for a fraction of the effort of professional "on-site reconnaissance." The research questions are: How to accommodate the expert language to be well understood by non-experts? What methods will non-experts use for measurements? How to efficiently visualize pedestrian segments on a map? What is the quality of non-expert collected geodata? What is the efficiency of introduced gamification elements?

Related Work

Recently, there were attempts to improve sidewalk accessibility using Google Street View: a collection of crossroads data [START_REF] Guy | Crossingguard: exploring information content in navigation aids for visually impaired pedestrians[END_REF] and public transport stations locations [START_REF] Hara | Improving public transit accessibility for blind riders by crowdsourcing bus stop landmark locations with google street view: An extended analysis[END_REF] to be described to visually impaired people, or barriers on sidewalks and crosswalks [START_REF] Hara | Combining crowdsourcing and google street view to identify street-level accessibility problems[END_REF] to hint wheelchair users about accessibility. However, neither used the data in sidewalk-based GIS to enable efficient routing and route description.

Comparing the quality of crowdsourced geodata from experts and non-experts, See et al. [START_REF] See | Comparing the quality of crowdsourced data contributed by expert and non-experts[END_REF] conclude that it do not differ significantly and non-experts can improve using training or examples (especially concerning accessibility where they are not as proficient [START_REF] Zeng | Improvement in environmental accessibility via volunteered geographic information: a case study[END_REF]). Moreover, the crowd can not only provide the data, but also provide their validation [START_REF] Goodchild | Assuring the quality of volunteered geographic information[END_REF]. Regarding motivation of the crowd, Mooney and Corcoran [START_REF] Mooney | Characteristics of heavily edited objects in openstreetmap[END_REF] conclude that majority of geodata is often contributed by the minority of users. On the other hand, crowdsourcing geodata that brings benefit to the community of contributors can be used as a motivation [START_REF] Klettner | Acquisition and cartographic applications of subjective geodata[END_REF]. The gamification proved to be a good motivation for crowdsourcing, using concepts like points, leaderboards, etc. [START_REF] Hamari | Does gamification work?-a literature review of empirical studies on gamification[END_REF].

Crowdsourcing of Accessibility Attributes

In our research, we consider following scenarios of crowdsourcing: 1) collecting new attributes for the features like sidewalk slope and material, corner shape, crosswalk curbs, ramps and signalization, 2) reporting temporary obstacles like potholes or construction works, 3) crowd validation of the crowdsourced geodata.

Design process and preliminary results

The expert language is often complex and not well understood by non-experts. To observe relevant non-expert language conventions for attributes description and their skills when collecting accessibility geodata without any special equipment, we organized three focus group sessions with 11 participants of various age (22-26, 27-35, 35-51).

Each group received a simplified hand-drawn map of pedestrian segments with line and point features of our interest (see Fig. 1a). The tasks were to name depicted features and collect data about their accessibility attributes. We were interested mainly in the shapes of corners, properties of crosswalks (such as a presence of tactile pavement, audio signalization, a presence of ramp or curb), positions of obstacles, passable widths, slopes and materials of pedestrian segments and properties of tram stops.

All participants were able to agree on a single term for given features. On the other hand, the participants struggled to name some of their attributes (e.g., the shape of a corner, different kinds of a slope, type of tactile paving surfaces). Regarding the slope, in the end, participants agreed on "direct slope" for longitudinal slope and "side slope" for cross slope.

The participants were not provided with any special tools for measuring required attributes. For measuring length, width, and depth, the most common technique was stepping or using their feet. They also used credit cards and squared paper as compensation for a meter (see Fig. 1b). However, the participants struggled to measure an exact slope of pedestrian segments; they even tried using a mobile app. However, it was not sensitive enough. Instead, they used terms as "gentle," "small," "smooth" or "slightly" uphill/downhill.

Based on the results from focus groups, we designed pictograms in combination with easy-to-understand language for the description of pedestrian segment features and their attributes. We conducted 4 design probe sessions based on paper mock-ups concluding that most participants do not want to spend too much time collecting the geodata and they proposed faster methods of input such as sliders, drop-down menus, or drag&drop instead of text fields for precise values. Further, they doubted clarity of pictograms for complicated attributes such as a presence of guiding lines for visually impaired on crosswalks and they mentioned that they would prefer additional photo example.

Gamification elements

Further, we elaborated on suitable gamification elements to engage crowdsourcing activities. Based on [START_REF] Hamari | Does gamification work?-a literature review of empirical studies on gamification[END_REF], we selected weekly and overall leaderboards, badges, weekly missions -where the task is to collect accessibility attributes for a particular combination of features, and credibility -based on validation of user's crowdsourced data by other users. Moreover, we introduced personalizations such as profile photo and nickname. These gamification elements were later included in a further design process.

Next steps

Currently, we are creating a hi-fi prototype using HTML and JavaScript. The main challenges are a visualization of the pedestrian segments, features and attributes over Google Maps on a mobile device; and how to support the identification of the desired features or reported obstacles by non-expert users (see Fig. 2). After the usability inspection of the hi-fi prototype, we plan to conduct a long-term experiment evaluating the quality of collected accessibility attributes and efficiency of gamification elements.

Conclusion

We present first design steps of the application for crowdsourced collection of pedestrian accessibility attributes in the urban environment. Focus group sessions were directed at accommodation of the expert language to non-expert users and the methods they can use for attributes measurement. Created paper mockup was evaluated in design probes. In the future, we aim to compare the quality of the collected data by non-experts and efficiency of gamification elements.

Fig. 1 .

 1 Fig. 1. a) A map representing template of the GIS -shapes depict features for which the attributes were collected; b) examples of measuring methods used.

Fig. 2 .

 2 Fig. 2. From the left: a pedestrian segment visualization with features; gamification elements; obstacle reporting; crosswalk ramps; recapitulation of collected data.

Route4All -http://www.route4all.eu/en/

Acknowledgements The research has been supported by the project Navigation of handicapped people funded by grant no. SGS16/236/OHK3/3T/13 (FIS 161 -1611663C000) and by Czech Radio Foundation project "Světluška".


Aditi Nettar

Nishita Chowdhari
email: nishitac123@gmail.com

Ro Xan

Karan Jia

Pallavi Rao Gadahad
email: pallavi.rao@nmims.edu

Sneha Deshmukh
email: sneha.deshmukh@nmims.edu

M Ukesh Patel

Design and Development of a Location-Based Social Networking Mobile Application

Keywords: Location based design, Social networking, M obile application

Location based services in social networking mobile applications are on the rise. Considering the benefits of incorporating location for collaboration amongst users, we were approached by a client to develop a location based social networking mobile application for a specific requirement. The mobile application thus developed was evaluated with users. Findings from the user study are summarized and recommendations for implementation and adoption of location based mobile social networking applications are discussed.

Introduction

With the advent and growing ubiquity of mobile devices, there has been an increased use of such devices for social interactions. A significant value addit ion to such mobile social networking platforms can be in the form of location based services. Considering the benefits of incorporating location in mobile social networking platform, we were approached by a client to develop a location based mobile application for parents to collaborate. Our client, being a single working parent who had newly shifted to an area, faced problems because she did not know many other parents in the vicinity. As she did not have time to go and network with other parents in the vicinity, she realised the need of having a location based social networking mobile platform for parents to collaborate and requested us to build such an application (app). Before proceeding with the app development, we delved into the challenges of incorporating location based services in mobile apps. One of the main technical challenges was excessive bandwidth consumption due to rendering of maps. Several mobile apps, particularly those developed for the tourism and travel domain, make use of maps to optimise user experience. Maps are one of the important visual cues in the case of location as they aid the user to view his or her position with respect to other elements in the app. However, the difficulty of rendering maps due to excessive bandwidth consumption must be considered, as well as privacy aspects of displaying location [START_REF] Tan | A Glimpse into the Research Space of Location Based Services[END_REF]. In this regard, studies [START_REF] Tan | A Glimpse into the Research Space of Location Based Services[END_REF][START_REF] Zipf | User-adaptive maps for Location-Based Services (LBS) for tourism, Information and communication technologies in tourism[END_REF][START_REF] Li | Analysis of a Location-Based Social Network[END_REF] emphasise the importance of giving users the control and choice to specify the situations where they want to reveal their location and also allow them the flexib ility of choosing how it is displayed to other users.

Apart from the above technical challenge, users' privacy is also considered as one of the critical challenges in designing location based services [START_REF] Wang | M obile Social Networking and Computing: A M ultidisciplinary Int egrated Perspective[END_REF]. However, past studies conducted in investigating users' perception towards sharing their location in a mobile platform, have contradicting viewpoints. For example, Tan et al [START_REF] Tan | A Glimpse into the Research Space of Location Based Services[END_REF] highlights that users are reluctant to share their location with unknown users and discuss privacy controls to limit display of such information. On the contrary, Barkuus and Dey [START_REF] Barkuus | Location-Based Services for M obile Telephony: a Study of Users' Privacy Concerns[END_REF] state that the willingness of a user to share their location is direct ly correlated to the usefulness of the app to the user. While distinguishing between position aware apps (which simp ly displays users' location, automatically retrieved by the app or device) and location tracking apps (which actively use users' location to perform a task, typically mapping or tracking the users' route), the researchers [START_REF] Barkuus | Location-Based Services for M obile Telephony: a Study of Users' Privacy Concerns[END_REF] claim that location tracking apps are more intrusive than position aware apps. Thus, users were comfortable using and sharing location in position aware apps, particularly for socialising. In line with these findings, in a study on understanding the impact of location sharing on users' privacy, Fusco et al [START_REF] Fusco | Location-Based Social Networking: Impact on Trust in Relationships[END_REF], say that users' comfort with sharing their location increases over a period of time and with increased use.

After explo ring the literature, we understood the technical challenges involved in developing location based services in mobile apps and incorporated a few suggestions to our design as suggested in the literature. It is also observed that, past studies have differing views on users' perceptions towards sharing location with unknown users. For investigating this further, we conducted user studies with real users. In sum, the purpose of this case study is to design, develop and evaluate location based services in a mobile social networking application for parents to collaborate.

Design and Development

For the time being, our client is interested only in the basic aspects in the app. She has plans to commercialize this later with added features. The beta version of the app we developed main ly consists of a location specific d iscussion forum for parents to collaborate. Along with this, there are other features such as book swap to facilitate cre ation of a virtual library, a message feature enabling one to one communication b etween parents and calendar synchronisation to keep track of scheduled events. The app was developed using Android Studio. Considering that the primary focus of our users is to get to know other parents who live in areas near to them and not their exact location, we realised that we do not need to make extensive use of maps. This gives our users the privacy of not sharing their exact location as well as the ben efit of interaction driven by location. Minimising the use of maps also enables faster rendering of screens and processing of location informat ion, thus improving the overall user experience. Further, location filtering is done internally by the system and the area of filtering is visible to the user as text. However, the user must be aware of his own location so that he can make effective use of the app. To ensure this, we have provided the user a map as well as a text d isplay of his location on his home screen .

Filtering threads by location is done by comparing the location value for the threads from the database to the current location. Threads are displayed if the area value in the address matches the user location area value. Filtering is done in a similar manner for other features of the app such as the book swap feature, which shows users, the books available in their vicinity.

User Study

After implementing the beta version of the app, we evaluated it with nine parents (ages 43 to 46; six female and three male). These parents main ly use location tracking apps (Google maps, Ola/Uber services) and find them very useful though some of them raised privacy concerns. We gave a few tasks (such as opening and participating in a discussion thread, lending and borrowing books and creating an event to meet a parent) to the partic ipants and observed them wh ile they performed these tasks. All the participants were able to co mplete the tasks quickly (10 to 15 minutes). After the participants completed the tasks given to them, we interviewed them to probe further about their opinion on our app. The observation and interview sessions were audio recorded and transcribed individually and analyzed qualitatively. The analysis showed that all the study participants found that adding "location" to the discussion forum is very useful, ma king it a great source of finding help nearby and bringing parents together. Many of them specifically mentioned that "location filtering" is a very useful feature.

When asked about any concerns using these apps, two of the participants raised concerns on the topic of discussions in the forum and that there should be a mature communicat ion. About future usage of this app, all the participants were ready to download and use it if launched on the Google Playstore. They felt that incorporating location in such discussion forums is an interesting concept and it will be of g reat help for parents to collaborate. One of the participants said that the app is a great beta ve rsion as the idea behind it is very good and upon refining it further, it can be an extremely useful app. Few participants suggested adding a nearby events feature to the app for sharing informat ion of upcoming events in the vicinity.

Challenges

One of main concerns in incorporating location is users' privacy. In order to handle this, we did not make extensive use of maps in our app (unlike location tracking apps, our users simply need to know other parents in the vicinity, not their exact location). This gives our users the privacy of not sharing their exact location. Minimising the use of maps also enabled faster rendering of screens. However, a few participants in our user study still raised privacy concerns but found our app useful and did not mind sharing their location. The idea of collaborating with other parents might have made the participants feel more secure. A lso, as highlighted by Barkuus and Dey [START_REF] Barkuus | Location-Based Services for M obile Telephony: a Study of Users' Privacy Concerns[END_REF], people are comfortable sharing location in position aware apps (like ours) rather than location tracking apps.

Another concern by the study participants was having mature content in the discussion forum as it is about parents discussing about their children and their activ ities.

We have incorporated a moderator facility in the forum, ensuring that content can be moderated by the moderators , depending on how appropriate it is .

All the study participants were ready to use this app in future when it is refined and launched on Google Playstore as they found location based social networking apps an interesting and useful concept. Perhaps people are becoming comfo rtable with sharing location as the benefits they offer outweigh any concerns. Also, when the requirement is specific, they prefer such apps over social media groups. As hig hlighted by one of the study participants, these apps present informat ion in an organized manner unlike any social media groups.

Recommendations

The study conducted showed that filtering threads by location is a very useful feature in the app. Also, there were suggestions for adding a "nearby events" feature for sharing information about upcoming events in the vicinity. Adding events such as book sale in the vicin ity is not only useful for parents but can be commercially beneficial. We plan to incorporate this feature as well some other features (as requested by our client) befo re releasing the app to the market. Implementation of location based services helps to build communities of support in the vicinity by facilitating communication and collaboration among users. The beta version of the app is an initial step in understanding the challenges of developing location based services in mobile social networking platform. The small scale user study may not be an actual indication of users' adoption intentions. Large scale investigation is preferred in this regard. However, designers and developers can use the recommendations summarized in this study for considering viable approaches to ta king location based technology ahead.


Eunice Sari
email: eunice.sari@acm.org

Adi Tedjasaputra
email: adit@acm.org

Designing Valuable Products with Design Sprint

Keywords: product, design, sprint, designsprint, designthinking, business, teamwork, agile, ux, process

The shift of creating valuable products, from only aesthetically pleasing, usable, or loveable products, has required adjustment of skills to create value as well as a mindset change. Instead of spending weeks and months to design a product, a rapid validation process takes place to explore how a product should be transformed into a valuable one. This course will teach the participants several key Design Sprint techniques in a nutshell (80 minutes). Google Ventures initially introduced Design Sprint to tackle critical business problems and come up with viable solutions within five days. Open to anyone who is involved in product and service design, the course aims to teach Design Sprint key techniques to create meaningful insights and hands-on experience for the participants. At the conclusion of the course, the participants are expected to envision how the lessons learned from the course can be applied in either academia or industry.

Introduction

Many organizations are getting better in designing aesthetically pleasing, usable, or loveable products. At the same time, in many product design processes, great physical forms, appearances and features are still often considered as the main factors that determine the success of a product. Spending a significant amount of resources, i.e. time, financial and human resources to design a product does not always create value to stakeholders, i.e. investors, companies, organizations or intended users. Thus, there has been a shift in paradigm to design valuable products with minimum resources.

In Human-Computer Interaction (HCI), user satisfaction can be increased by improving usability and accessibility of the product. Through User Experience (UX), user motivation and interaction are closely examined during a design process to plan for a successful adoption and acquisition.

To make this process more systematic, Google Ventures (GV) have created a framework to tackle the issues of designing value in the product using Design Sprint technique [START_REF] Knapp | Sprint: How to Solve Big Problems and Solve New Ideas in Just Five Days[END_REF]. This technique has been applied internally for Google products, as well as extensively across the world to design and develop many award-winning products. The agility and effectiveness of Design Sprint has allowed for innovations that transform many companies and organizations.

Google Design Sprint

Design Sprint has been considered as an effective framework to validate ideas through rapid prototyping and user testing, and contains five stages: Understand, Diverge, Decide, Prototype, and Validate.

The Course

At INTERACT 2017, we deliver the introductory course on Designing Valuable Products with Design Sprint to showcase how UX professionals apply Design Sprint techniques to design and develop valuable products and services. During the course, we will introduce the 5-day techniques in a nutshell to give insights for the participants to experience the Design Sprint.

The course participants will be guided to develop solutions for a problem using stepby-step Design Sprint techniques. The participants will engage in a group of 4-5 people in various hands-on activities. The maximum number of participants who can take part in this course is 40 people, preferably a good mixed of academia and industries. There is no specific requirement for potential participants to participate in this 80-minute hands-on activity. Anyone who are involved in the design and development of products or services, decision makers, business people, developers, researchers are encouraged to participate in this course.

By the end of the course, it is expected that the participants get meaningful insight about Design Sprint techniques and to be able to envision how the Design Sprint techniques can be applied to their own contexts at either academia or industries.

Dr Eunice Sari

Eunice is the CEO and Co-Founder of UX Indonesia, the first and premier UX Consulting, Training and Research company based in Indonesia. She is a leading UX/CX and ICT in Education Expert with more than 15+ years of experience working in both academia and industries. She has pioneered a number of forwardthinking and innovative projects, such as user experience for digital products and services, mobile learning, Internet of Things (IoT), service design and online community in order to effect changes in life and improve the bottom line of business in various vertical industries in USA, Europe, Australia and Asia.

She co-founded and chaired the Indonesia ACM SIGCHI Chapter (Association Computing Machinery Special Interest Group on Computer-Human Interaction a.k.a CHI UX Indonesia), and later the Association of Digital Interaction Indonesia -Perkumpulan Interaksi Digital Indonesia (PIDI). She is also the co-founder of ACM SIGCHI Southeast Asia community, the South East Asia Liaison for ACM SIGCHI Asia Development Committee, the Expert Member of the International Federation for Information Processing (IFIP) TC 13 -Human Computer Interaction (HCI) for Indonesia, and the Western Australia Representative for the Human Factors Ergonomic Association Computer Human Interaction Special Interest Group (HFESA CHISIG). With her roles, she facilitates the collaboration between academia and industry in the fields of Education, Technology, HCI and UX.

At Google, Eunice is the first female Google Expert in UX/UI from Indonesia who has helped hundreds of international startups from Indonesia, USA, Australia, Ireland, Brazil, India and Southeast Asian countries through Google Launchpad and Accelerator Programs to improve a range of complex product and service portfolios, evaluate them with users, as well as facilitating design and business workshops with key stakeholders. In addition to that, she is also a Google Certified Design Sprint Instructor who has run a number of public and private design sprint activities with startups and established organizations in many countries.

With her seasoned international experience from industry and academic, Eunice is passionately interested to help international business clients design experience strategy and roadmap that exceed customer expectations.

Josh (Adi Tedjasaputra, M.Sc)

Josh is the Director and Co-Founder of UX Indonesia, who has been working in both academia and industries for more than 15 years. Josh has a passion for the design, development, and use of Information and Communication Technology (ICT) for a better life. He has helped many companies, educational and non-profit organisations in Europe and Asia Pacific to achieve their business goals and make the best investment in ICT.

(a) Step 1 -

 1 Understand: Participants evaluate the problem they are trying to solve, the personas they are designing for, and the form factor they are going to use. (b) Step 2 -Diverge: Participants are encouraged to let go of all their presumptions and engage in different activities to generate as many ideas as they can, regardless of how feasible or far-fetched they are. (c) Step 3 -Decide: Through different activities, participants decide which ideas to pursue further. (d) Step 4 -Prototype: Participants rapidly sketch, design and prototype their ideas, concentrating on User Interface (UI) flow. (e) Step 5 -Validate: Participants put their product in front of users, test and are encouraged to show and tell when possible.

With his engineering and computer science background, he has introduced forward-thinking and innovative projects that improve the bottom line of businesses in different vertical industries through Human-centred design, computing and engineering.

Josh is currently leading the Indonesia ACM SIGCHI Chapter in Indonesia and running annual international HCI and UX conference mainly for Southeast Asian practitioners and academics in the region. At Google, Josh has been a global mentor for international startups in addition to his contribution to the development startup ecosystem in Indonesia. Josh has also been running a number of public and private Design Sprint activities His current interests include the Internet of Things, Human-centred Computing, Computational Thinking, e-Learning, Moodle, WordPress and Agile and Lean UX.