User authentication on publicly exposed terminals with established mechanisms, such as typing the credentials on a virtual keyboard, can be insecure e.g. due to shoulder surfing or due to a hacked terminal. In addition, username and password entry can be time-consuming and thus improvable with relation to usability. As security and comfort are often competing with each other, novel authentication and authorization methods especially for public terminals are desirable. In this paper, we present an approach on a distributed authentication and authorization system, where the user can be easily identified and enabled to use a service with his smartphone. The smartphone (as personal and private device the user is always in control of) can provide a highly secure authentication token that is renewed and ex- changed in the background without the user’s participation. The claimed improvements were supported by a user sur- vey with an implementation of a digital room management system as an example for a public display. The proposed au- thentication procedure would increase security and yet enable fast authentication within publicly exposed terminals.

1. Technische Universität München
Visual Authentication
A Secure Single Step Authentication for User Authorization
Luis Roalter 1, Matthias Kranz 2, Andreas Möller 1, Stefan Diewald 1,
Tobias Stockinger 2, Marion Koelle 2, Patrick Lindemann 2
1 Technische
Universität München
2 Universität Passau
December 5th 2013
Mobile and Ubiquitous Multimedia (MUM 2013), Luleå, Sweden

2. Technische Universität München
mobile & usable
security
for interaction with
public terminals
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MUM 2013 Presentation: Visual Authentication – A Secure Single Step Authentication for User Authorization
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3. Technische Universität München
Current Situation
username 1
password 1
username 2
password 2
username 3
password 3
username 4
password 4
Different credentials
username 5
password 5
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username 6
password 6
username 8
password 8
MUM 2013 Presentation: Visual Authentication – A Secure Single Step Authentication for User Authorization
image source: http://commons.wikimedia.org/wiki/File:Singapore_Road_Signs_-_Restrictive_Sign_-_Stop_-_Security_Check.svg
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4. Technische Universität München
Federated Authentication: Single Sign-On (SSO)
Related Work
•
Sign in once to use all services
•
Single, familiar login mask for
different services, e.g.
– “Sign in with Facebook”
– “Sign in with Google”
•
One username, one password
•
Improved user experience
Optional: two-factor authentication
with side channel, e.g. mobile phone
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MUM 2013 Presentation: Visual Authentication – A Secure Single Step Authentication for User Authorization
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5. Technische Universität München
Increased Security: Multi-Factor Authentication
Related Work
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MUM 2013 Presentation: Visual Authentication – A Secure Single Step Authentication for User Authorization
image source: Microsoft Office Online Clipart Gallery
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6. Technische Universität München
Problems in the Context of Mobile and Usable Security
•
•
Security-centered issues
– Access credentials can be stolen, e .g.
• man-in-the-middle attack
• shoulder surfing
• phishing
as the terminal usually does not authenticate towards the user
– Trust relationship towards the device might be limited, even if the device
can prove its identity, e.g. if it is a shared device
à lack of trust, reluctant to use services, …
Device-centered issues
– Limited capabilities of the input device (e.g. no keyboard)
– Limited ergonomics (e.g. wall-mounted device)
– hygiene concerns
à time-consuming, uncomfortable, …
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MUM 2013 Presentation: Visual Authentication – A Secure Single Step Authentication for User Authorization
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7. Technische Universität München
Proposal: Usable Security with Single Step Authentication
sessionID: xyz
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MUM 2013 Presentation: Visual Authentication – A Secure Single Step Authentication for User Authorization
image source: Microsoft Office Online Clipart Gallery
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8. Technische Universität München
Proposal: Additional Benefits of the Mobile Authenticator
• User-enabled Session Management
- Remote session logout
- Session transfer between systems
• Maintenance of profile and personal
information
à Transparency to the user (full information)
• Without mobile authenticator app:
can be used with a web-based interface
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MUM 2013 Presentation: Visual Authentication – A Secure Single Step Authentication for User Authorization
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9. Technische Universität München
Example Use Case: Room Reservation and Access
•
Tablet PC as digital door sign for meeting rooms
•
Provides resource-centred information and access
(e.g. seeing when rooms are occupied or available)
•
Use case:
Book a room through the public display
– Need for authentication & authorization
(accounting - who reserved the room?)
– Single Sign-On with QR code & mobile
(no credentials to type on public display
– Allows physical room access & usage
(remotely controlled digital door lock)
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MUM 2013 Presentation: Visual Authentication – A Secure Single Step Authentication for User Authorization
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10. Technische Universität München
Example Use Case: How does it work?
User is scanning a QR code with smartphone
(containing a session token, SID), data sent to IdP
with user credentials (user name & password)
Case 1: Authenticator app installed
• Credentials (which were previously
stored in app once) and session token
are sent to the service
• The user is authenticated in one step
Case 2: No authenticator app installed
• Redirection to a web page where
credentials are entered (securely on
mobile device)
• The URI is recognized by the tablet and
authenticates the user
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MUM 2013 Presentation: Visual Authentication – A Secure Single Step Authentication for User Authorization
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11. Technische Universität München
Example Use Case: Initial User Study with “Room Access”
•
Initial user survey with the prototype system (room access)
– 20 participants (18 males, 2 females) aged between 20 and 64 years
– (non-balanced, non-representative, not providing statistically usable results)
•
RQ1: Do users have security concerns when entering
personal credentials on a public display?
– Participants agreed that they have security concerns entering personal
information on a publicly exposed display
– Avg. 3.8 on 5-step Likert-Scale (fully disagree = 1, fully agree = 5), SD=1.3
•
RQ2: Do users have security concerns when using the smartphone-based
visual authentication system in conjunction with a public display?
– Participants agreed that they have security concerns in the smartphonebased authentication approach
– Avg. 2.3 on 5-step Likert-Scale (fully disagree = 1, fully agree = 5), SD=1.4
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12. Technische Universität München
Summary and Discussion
Proposed approach for “mobile usable security” providing user-friendly multifactor authentication in a public-private device scenario, addressing
• input modalities and device
(replacing potentially non-convenient input methods, hygiene aspects, …)
• security issues
(SSO with side-channel authentication, prohibiting shoulder surfing, phishing
attacks, potential to de-authenticate sessions remotely, trusted …)
• usability aspects
(less error-prone, faster, more convenient, …)
Open Issues
• Multiple identity providers require pre-established trust relationships
• Network connection for side-channel/multi-factor authentication needed
• Shift of responsibility to the user (non-expert in security issues)
• Device-to-device communication problems (visible lighting, (audible) noise, …)
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13. Technische Universität München
Outlook and Future Work
•
•
•
Technical enhancement
– Pluggable Authentication Module (QR code-based PAM module) for PC login
– Transfer of running sessions and their contexts between terminals
Usability evaluation and user study
– Acceptance and usability tests
• in a real-world deployment
• w.r.t. long-term effects on usable security
– Investigation of novel applications and domains and scenario-specific
potentials (public displays, distributed environments, internet of things)
Security evaluation
– Resistance to man-in-the-middle/replay attacks
– Simulate different hacking scenarios
– Creation of an overall security concept
– Extended information (e.g. WLAN AP scan, GPS, etc. to detect “fakes”)
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14. Technische Universität München
Thank you very much for your kind attention!
Questions?
?
?
Contact:
Luis Roalter (roalter@tum.de)
Matthias Kranz (matthias.kranz@uni-passau.de)
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15. Technische Universität München
Citation Information
•
Please cite this work as follows:
L. Roalter, M. Kranz, A. Möller, S. Diewald, T. Stockinger, M. Koelle, P. Lindemann: Visual
Authentication - A Secure Single Step Authentication for User Authorization. In: Proceedings of the
12th International Conference on Mobile and Ubiquitous Multimedia (MUM 2013), Luleå, Sweden,
2013
•
Please use the following BibTex file:
@inproceedings{MUM2013Roalter,
author = {Roalter, Luis and Kranz, Matthias and M"{o}ller, Andreas and Diewald,
Stefan and Stockinger, Tobias and Koelle, Marion and Lindemann, Patrick},
title = {Visual Authentication – A Secure Single Step Authentication for User
Authorization},
booktitle = {Proceedings of the 12th International Conference on Mobile and Ubiquitous
Multimedia},
series = {MUM '13},
year = {2013},
location = {Luleaa, Sweden},
publisher = {ACM},
address = {New York, NY, USA},
} "
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