These are the papers CASA and the HGI will be presenting at CHI 24

The CHI takes place this year from May 11-16 in Honolulu, USA.

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At this year's Conference on Human Factors in Computing Systems (CHI), , which will take place from May 11-16 in Honolulu, scientists from the Cluster of Excellence CASA and the Horst Görtz Institute for IT Security will be represented with several papers. You can find a detailed list in the overview and a link to the video presentation.

Two of the papers will be honored with an Honourable Mention Award : The paper “Do You Need to Touch? Exploring Correlations between Personal Attributes and Preferences for Tangible Privacy Mechanisms” by CASA PI Karola Marky and CASA PhD Priyasha Chatterjee (et al.) and the paper ‘A Comparative Long-Term Study of Fallback Authentication Schemes’ by HGI scientists Philipp Markert, Leona Lassak and CASA PI Markus Dürmuth (et al.).

CHI has been organized annually by the Association for Computing Machinery (ACM) since 1982. It is one of the leading conferences for interactive digital technologies with a focus on human-computer interactions.



I see an IC: A Mixed-Methods Approach to Study Human Problem-Solving Processes in Hardware Reverse Engineering
René Walendy, Markus Weber, Jingjie Li, Steffen Becker, Carina Wiesen, Malte Elson, Younghyun Kim, Kassem Fawaz, Nikol Rummel, Christof Paar

Trust in digital systems depends on secure hardware, often assured through Hardware Reverse Engineering (HRE). This work develops methods for investigating human problem-solving processes in HRE, an underexplored yet critical aspect. Since reverse engineers rely heavily on visual information, eye tracking holds promise for studying their cognitive processes. To gain further insights, we additionally employ verbal thought protocols during and immediately after HRE tasks: Concurrent and Retrospective Think Aloud. We evaluate the combination of eye tracking and Think Aloud with 41 participants in an HRE simulation. Eye tracking accurately identifies fixations on individual circuit elements and highlights critical components. Based on two use cases, we demonstrate that eye tracking and TA can complement each other to improve data quality. Our methodological insights can inform future studies in HRE, a specific setting of human-computer interaction, and in other problem-solving settings involving misleading or missing information.


Self-Efficacy and Security Behavior: Results from a Systematic Review of Research Methods
Nele Borgert, Luisa Jansen, Imke Böse, Jennifer Friedauer, Angela Sasse, Malte Elson

Amidst growing IT security challenges, psychological underpinnings of security behaviors have received considerable interest, e.g. cybersecurity Self-Efficacy (SE), the belief in one’s own ability to enact cybersecurity-related skills. Due to diverging definitions and proposed mechanisms, research methods in this field vary considerably, potentially impeding replicable evidence and meaningful research synthesis. We report a preregistered systematic literature review investigating (a) cybersecurity SE measures, (b) SE’s proposed roles, and (c) intervention approaches. We minimized selection bias by detailed exclusion criteria, interdisciplinary search strategy, and double coding. Among 174 cybersecurity SE studies (2010-2021) from 18 databases with 55,758 subjects, we identified 173 different SE measures with considerable differences in psychometric quality and validity evidence. We found 276 variables as assumed causes/outcomes of cybersecurity SE and identified 13 intervention designs. This review demonstrates the extent of methodological and conceptual fragmentation in cybersecurity SE research. We offer recommendations to inspire our research community toward standardization.



Do You Need to Touch? Exploring Correlations between Personal Attributes and Preferences for Tangible Privacy Mechanisms
Sarah Delgado Rodriguez, Priyasha Chatterjee, Anh Dao Phuong, Florian Alt, Karola Marky

This paper explores how personal attributes, such as age, gender, technological expertise, or "need for touch", correlate with people's preferences for properties of tangible privacy protection mechanisms, for example, physically covering a camera. For this, we conducted an online survey (N = 444) where we captured participants' preferences of eight established tangible privacy mechanisms well-known in daily life, their perceptions of effective privacy protection, and personal attributes. We found that the attributes that correlated most strongly with participants' perceptions of the established tangible privacy mechanisms were their "need for touch" and previous experiences with the mechanisms. We use our findings to identify desirable characteristics of tangible mechanisms to better inform future tangible, digital, and mixed privacy protections. We also show which individuals benefit most from tangibles, ultimately motivating a more individual and effective approach to privacy protection in the future.



Understanding Users' Interaction with Login Notifications
Philipp Markert, Leona Lassak, Maximilian Golla, Markus Dürmuth

Login notifications intend to inform users about sign-ins and help them protect their accounts from unauthorized access. Notifications are usually sent if a login deviates from previous ones, potentially indicating malicious activity. They contain information like the location, date, time, and device used to sign in. Users are challenged to verify whether they recognize the login (because it was them or someone they know) or to protect their account from unwanted access. In a user study, we explore users' comprehension, reactions, and expectations of login notifications. We utilize two treatments to measure users' behavior in response to notifications sent for a login they initiated or based on a malicious actor relying on statistical sign-in information. We find that users identify legitimate logins but need more support to halt malicious sign-ins. We discuss the identified problems and give recommendations for service providers to ensure usable and secure logins for everyone.



A Comparative Long-Term Study of Fallback Authentication Schemes
Leona Lassak, Philipp Markert, Maximilian Golla, Elizabeth Stobert, Markus Dürmuth

Fallback authentication, the process of re-establishing access to an account when the primary authenticator is unavailable, holds critical significance. Approaches range from secondary channels like email and SMS to personal knowledge questions (PKQs) and social authentication. A key difference to primary authentication is that the duration between enrollment and authentication can be much longer, typically months or years. However, few systems have been studied over extended timeframes, making it difficult to know how well these systems truly help users recover their accounts. We also lack meaningful comparisons of schemes as most prior work examined two mechanisms at most. We report the results of a long-term user study of the usability of fallback authentication over 18 months to provide a fair comparison of the four most commonly used fallback authentication methods. We show that users prefer email and SMS-based methods, while mechanisms based on PKQs and trustees lag regarding successful resets and convenience.



Decide Yourself or Delegate - User Preferences Regarding the Autonomy of Personal Privacy Assistants in Private IoT-Equipped Environments
Karola Marky, Alina Stöver, Sarah Prange, Kira Bleck, Paul Gerber, Verena Zimmermann, Florian Müller, Florian Alt, Max Mühlhäuser

Personalized privacy assistants (PPAs) communicate privacy-related decisions of their users to Internet of Things (IoT) devices. There are different ways to implement PPAs by varying the degree of autonomy or decision model. This paper investigates user perceptions of PPA autonomy models and privacy profiles - archetypes of individual privacy needs - as a basis for PPA decisions in private environments (e.g., a friend's home). We first explore how privacy profiles can be assigned to users and propose an assignment method. Next, we investigate user perceptions in 18 usage scenarios with varying contexts, data types and number of decisions in a study with 1126 participants. We found considerable differences between the profiles in settings with few decisions. If the number of decisions gets high (  1/h), participants exclusively preferred fully autonomous PPAs. Finally, we discuss implications and recommendations for designing scalable PPAs that serve as privacy interfaces for future IoT devices.




Out-of-Device Privacy Unveiled: Designing and Validating the Out-of-Device Privacy Scale (ODPS)
Habiba Farzand, Karola Marky, Mohamed Khamis

This paper proposes an Out-of-Device Privacy Scale (ODPS) - a reliable, validated psychometric privacy scale that measures users’ importance of out-of-device privacy. In contrast to existing scales, ODPS is designed to capture the importance individuals attribute to protecting personal information from out-of-device threats in the physical world, which is essential when designing privacy protection mechanisms. We iteratively developed and refined ODPS in three high-level steps: item development, scale development, and scale validation, with a total of N=1378 participants. Our methodology included ensuring content validity by following various approaches to generate items. We collected insights from experts and target audiences to understand response variability. Next, we explored the underlying factor structure using multiple methods and performed dimensionality, reliability, and validity tests to finalise the scale. We discuss how ODPS can support future work predicting user behaviours and designing protection methods to mitigate privacy risks.



Beyond Aesthetics: Evaluating Response Widgets for Reliability & Construct Validity of Scale Questionnaires
Habiba Farzand, David Al Baiaty Suarez, Thomas Goodge, Shaun Alexander Macdonald, Karola Marky, Mohamed Khamis, Paul Cairns

Scale questionnaires are psychometric tools that capture perspectives and experiences. Consequently, these tools need to be reliable and valid. In this paper, we investigate the impact of response widgets - the UI elements that allow users to answer scale items - on the overall scale reliability and construct validity of three varied length scale questionnaires in a user study (N=30). Our results reveal that optimum reliability was achieved using radio buttons and dropdowns in all varied-length questionnaires. Further, valid results were produced utilising the slider and dropdown. No significant differences were found in time consumption, but click count was significantly higher with dropdown. Radio buttons scored lower in format satisfaction than others, and dropdown was the least effective in ease of selection and quick completion. In light of these results, we conclude that response widgets are more than just aesthetics and should be selected as per the researcher's aims.



General note: In case of using gender-assigning attributes we include all those who consider themselves in this gender regardless of their own biological sex.