Florentin Putz, M.Sc.

Strong authentication on all layers / Acoustic communication / Researcher

Contact Information

Pankratiusstraße 2
D-64289 Darmstadt
S2|20 203
fputz@seemoo.tu-darmstadt.de
+49 6151 16-25475
+49 6151 16-25471

Biography

Florentin Putz is a researcher at the Secure Mobile Networking Lab. His research focuses on strong authentication on all layers, for example: Improving the design of authentication tokens, or innovative physical layers for device pairing (e.g., acoustic communication), or applications using the FIDO2 standards. He received his B.Sc. (2016) and M.Sc. (2019) degrees from Technical University of Darmstadt, Germany. During his master’s studies, he was a visiting graduate student at the University of British Columbia, Canada. He is recipient of the Best Student Award (for the best master’s degree at the electrical engineering department), the Datenlotsen Award (for an outstanding master’s thesis), and the KuVS Award 2020 (nationwide award from the German special interest group on Communication and Distributed Systems).

Here you can find the PDF version of our recent publication on FIDO2 extensions:

F. Putz, S. Schön, M. Hollick. Future-Proof Web Authentication: Bring Your Own FIDO2 Extensions. In: 4th International Workshop on Emerging Technologies for Authorization and Authentication. ETAA 2021. Springer LNCS 13136, pp. 17–32, 2021. https://doi.org/10.1007/978-3-030-93747-8_2

PDF author version

Research Interests

Strong Authentication
Usable Security
Device Pairing
Acoustic Communication
Hierarchical Modulation

Teaching

Coordination and teaching assistant of course Physical Layer Security in Wireless Systems
Selected seminar topics in (Advanced) Seminar on Networking, Security, Mobility, and Wireless Communications
Selected lab topics in Secure Mobile Networking Lab/Project

Offered Theses Topics

Type

Year

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2022 In progress

Smartphone Pairing Schemes

Supervisor: Florentin Putz

Summary

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2022 Open

Acoustic Communication: Ubiquitous ad-hoc communication?

Supervisor: Florentin Putz

Summary

I offer challenging topics on all aspects of the acoustic physical layer, which allows smartphones to use their integrated audio hardware for aerial communication, similar to wireless radio communication. The main use case is short-range communication, e.g., for pairing.The advantage: We can implement custom physical layers without expensive SDRs.

Contact me if you have any research ideas on this topic. Experience with signal processing is recommended.

2021 Completed

FIDO2 Platform Authenticators

Supervisor: Florentin Putz

Summary

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2021 Completed

Evaluation of Acoustic Communication Schemes

Supervisor: Florentin Putz

Summary

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2021 In progress

Impact of Multi-Path Effects on Acoustic Keylogging Systems

Supervisor: Matthias Gazzari Florentin Putz

Summary

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2021 Completed

Evaluation of Ultra-Wideband for Secure Device Pairing

Supervisor: Alexander Heinrich Florentin Putz

Summary

Evaluation of Ultra-Wideband for Secure Device Pairing

2021 In progress

Enterprise Authentication Systems

Supervisor: Florentin Putz

Summary

Enterprise Authentication Systems

2021 Completed

Analyzing the Deployment of Device-Specific Android Security Features

Supervisor: Florentin Putz

Summary

Analyzing the Deployment of Device-Specific Android Security Features

2021 Completed

Investigating the Pitfalls of FIDO2 Usability in Practice

Supervisor: Florentin Putz

Publications

Type

Year

Show awards only

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2021 4th International Workshop on Emerging Technologies for Authorization and Authentication Conference

Future-Proof Web Authentication: Bring Your Own FIDO2 Extensions

Florentin Putz Steffen Schön Matthias Hollick

PDF BibTeX DOI: 10.1007/978-3-030-93747-8_2

Abstract

The FIDO2 standards for strong authentication on the Internet define an extension interface, which allows them to flexibly adapt to future use cases. The domain of establishing new FIDO2 extensions, however, is currently limited to web browser developers and members of the FIDO alliance. We show how researchers and developers can design and implement their own extensions for using FIDO2 as a well-established and secure foundation to demonstrate innovative authentication concepts or to support custom deployments. Our open-source implementation targets the full FIDO2 stack, such as the Chromium web browser and hardware tokens, to enable tailor-made authentication based on the power of the existing FIDO2 ecosystem. To give an overview of existing extensions, we survey all published FIDO2 extensions by manually inspecting the source code of major web browsers and authenticators. Their current design, however, hinders the implementation of custom extensions, and they only support a limited number of extensions out of the box. We discuss weaknesses of current implementations and identify the lack of extension pass-through as a major limitation in current FIDO2 clients.

2020 13th ACM Conference on Security and Privacy in Wireless and Mobile Networks Conference

Acoustic Integrity Codes: Secure Device Pairing Using Short-Range Acoustic Communication

Florentin Putz Flor Álvarez Jiska Classen

PDF BibTeX DOI: 10.1145/3395351.3399420

Abstract

Secure Device Pairing (SDP) relies on an out-of-band channel to authenticate devices. This requires a common hardware interface, which limits the use of existing SDP systems. We propose to use short-range acoustic communication for the initial pairing. Audio hardware is commonly available on existing off-the-shelf devices and can be accessed from user space without requiring firmware or hardware modifications. We improve upon previous approaches by designing Acoustic Integrity Codes (AICs): a modulation scheme that provides message authentication on the acoustic physical layer. We analyze their security and demonstrate that we can defend against signal cancellation attacks by designing signals with low autocorrelation. Our system can detect overshadowing attacks using a ternary decision function with a threshold. In our evaluation of this SDP scheme’s security and robustness, we achieve a bit error ratio below 0.1% for a net bit rate of 100 bps with a signal-to-noise ratio (SNR) of 14 dB. Using our open-source proof-of-concept implementation on Android smartphones, we demonstrate pairing between different smartphone models.