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TypeFormer: transformers for mobile keystroke biometrics

TypeFormer: transformers for mobile keystroke biometrics
TypeFormer: transformers for mobile keystroke biometrics

The broad usage of mobile devices nowadays, the sensitiveness of the information contained in them, and the shortcomings of current mobile user authentication methods are calling for novel, secure, and unobtrusive solutions to verify the users’ identity. In this article, we propose TypeFormer, a novel transformer architecture to model free-text keystroke dynamics performed on mobile devices for the purpose of user authentication. The proposed model consists in temporal and channel modules enclosing two long short-term memory recurrent layers, Gaussian range encoding, a multi-head self-attention mechanism, and a block-recurrent transformer layer. Experimenting on one of the largest public databases to date, the Aalto mobile keystroke database, TypeFormer outperforms current state-of-the-art systems achieving equal error rate values of 3.25% using only five enrolment sessions of 50 keystrokes each. In such way, we contribute to reducing the traditional performance gap of the challenging mobile free-text scenario with respect to its desktop and fixed-text counterparts. To highlight the design rationale, an analysis of the experimental results of the different modules implemented in the development of TypeFormer is carried out. Additionally, we analyse the behaviour of the model with different experimental configurations such as the length of the keystroke sequences and the amount of enrolment sessions, showing margin for improvement.

Biometrics, HCI, Keystroke dynamics, Mobile devices, Transformers
0941-0643
18531-18545
Stragapede, Giuseppe
f90048a3-7cac-400a-b241-1aa69d945e7a
Delgado-Santos, Paula
61d96aa4-4228-4b7d-9e55-45737560512e
Tolosana, Ruben
93125127-5ac2-4e76-94aa-4d09f28a3e51
Vera-Rodriguez, Ruben
d9c7e17e-332c-47ac-a9a9-30cc75d26a3e
Guest, Richard
93533dbd-b101-491b-83cc-39ccfdc18165
Morales, Aythami
158f3aeb-4e1d-49b2-854e-175946a4cb1f
Stragapede, Giuseppe
f90048a3-7cac-400a-b241-1aa69d945e7a
Delgado-Santos, Paula
61d96aa4-4228-4b7d-9e55-45737560512e
Tolosana, Ruben
93125127-5ac2-4e76-94aa-4d09f28a3e51
Vera-Rodriguez, Ruben
d9c7e17e-332c-47ac-a9a9-30cc75d26a3e
Guest, Richard
93533dbd-b101-491b-83cc-39ccfdc18165
Morales, Aythami
158f3aeb-4e1d-49b2-854e-175946a4cb1f

Stragapede, Giuseppe, Delgado-Santos, Paula, Tolosana, Ruben, Vera-Rodriguez, Ruben, Guest, Richard and Morales, Aythami (2024) TypeFormer: transformers for mobile keystroke biometrics. Neural Computing and Applications, 36 (29), 18531-18545. (doi:10.1007/s00521-024-10140-2).

Record type: Article

Abstract

The broad usage of mobile devices nowadays, the sensitiveness of the information contained in them, and the shortcomings of current mobile user authentication methods are calling for novel, secure, and unobtrusive solutions to verify the users’ identity. In this article, we propose TypeFormer, a novel transformer architecture to model free-text keystroke dynamics performed on mobile devices for the purpose of user authentication. The proposed model consists in temporal and channel modules enclosing two long short-term memory recurrent layers, Gaussian range encoding, a multi-head self-attention mechanism, and a block-recurrent transformer layer. Experimenting on one of the largest public databases to date, the Aalto mobile keystroke database, TypeFormer outperforms current state-of-the-art systems achieving equal error rate values of 3.25% using only five enrolment sessions of 50 keystrokes each. In such way, we contribute to reducing the traditional performance gap of the challenging mobile free-text scenario with respect to its desktop and fixed-text counterparts. To highlight the design rationale, an analysis of the experimental results of the different modules implemented in the development of TypeFormer is carried out. Additionally, we analyse the behaviour of the model with different experimental configurations such as the length of the keystroke sequences and the amount of enrolment sessions, showing margin for improvement.

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More information

Accepted/In Press date: 27 June 2024
e-pub ahead of print date: 30 July 2024
Keywords: Biometrics, HCI, Keystroke dynamics, Mobile devices, Transformers

Identifiers

Local EPrints ID: 492980
URI: http://eprints.soton.ac.uk/id/eprint/492980
ISSN: 0941-0643
PURE UUID: 43e2459b-65a3-428b-8bf2-c4f5715f5644
ORCID for Richard Guest: ORCID iD orcid.org/0000-0001-7535-7336

Catalogue record

Date deposited: 21 Aug 2024 17:06
Last modified: 01 Oct 2024 02:12

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Contributors

Author: Giuseppe Stragapede
Author: Paula Delgado-Santos
Author: Ruben Tolosana
Author: Ruben Vera-Rodriguez
Author: Richard Guest ORCID iD
Author: Aythami Morales

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