This deliverable combines much of the work within OCTAVE which has implemented hybrid solutions to automatic speaker verification and also innovative new countermeasure solutions to detect and prevent spoofing attacks of increasing sophistication and diversity. Key to the complementarity of the work reported here to that elsewhere within the OCTAVE work programme is the combination of automatic speaker verification with fully integrated spoofing countermeasures. While increasing security, they also have the potential to impact on the usability of OCTAVE systems; there is an inherent trade-off between the requirements for convenience and security. The analysis of the relationship between these two essentially competing requirements is the objective of the work reported herein. The empirical analysis involves the use of three different, standard corpora. Their use with four scenarios involving different text constraints encapsulates the two OCTAVE use cases, namely those of telephony banking, a logical access scenario, and a physical access scenario involving the protection of sensitive airport infrastructure. Each experimental condition includes a study of multiple automatic speaker verification frontends and multiple spoofing countermeasures. The study involving combined text constraints constitutes the hybrid condition. Furthermore, two different approaches to automatic speaker verification and spoofing countermeasure integration are considered: cascaded and parallel. The study is the broadest and deepest analysis of the convenience-security trade-off performed to date. The analysis of the convenience-security trade-off relates to the balance between false rejections and false acceptances. Spoofing attacks aim to provoke false acceptances; countermeasures aim to reduce them. However, any solution to deliver lower false acceptance in the form of spoofing countermeasures generally results in higher false rejection rates. Convenience, in contrast, demands low false rejection rates whereas this cannot be achieved without increasing the false acceptance rate, hence the need to properly understand the relationship between convenience and security in the OCTAVE project. Results reported in this deliverable show that the cascaded integration of speaker verification and spoofing countermeasures is a suitable approach, which preserves user convenience while greatly improving system reliability and security.

Source: WP 4 Hybrid Voice Biometrics

Dissemination level: Confidential

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