Privacy-enhancing technologies are technologies that implement fundamental data protection principles. With respect to biometric recognition, different types of privacy-enhancing technologies have been introduced for protecting stored biometric data which are generally classified as sensitive. In this regard, various taxonomies and conceptual categorizations have been proposed and standardisation activities have been carried out. However, these efforts have mainly been devoted to certain sub-categories of privacy-enhancing technologies and therefore lack generalization. This work provides an overview of concepts of privacy-enhancing technologies for biometric recognition in a unified framework. Key properties and differences between existing concepts are highlighted in detail at each processing step. Fundamental characteristics and limitations of existing technologies are discussed and related to data protection techniques and principles. Moreover, scenarios and methods for the assessment of privacy-enhancing technologies for biometric recognition are presented. This paper is meant as a point of entry to the field of data protection for biometric recognition applications and is directed towards experienced researchers as well as non-experts.

隐私增强技术是实现基本数据保护原则的技术。关于生物特征识别，已经引入了不同类型的隐私增强技术来保护通常被归类为敏感的存储的生物特征数据。在这方面，已经提出了各种分类法和概念分类，并开展了标准化活动。然而，这些努力主要致力于隐私增强技术的某些子类别，因此缺乏普遍性。这项工作概述了统一框架中生物识别的隐私增强技术的概念。每个处理步骤都详细强调了现有概念之间的关键属性和差异。讨论了现有技术的基本特征和局限性，并与数据保护技术和原则相关。此外，还提出了评估生物特征识别隐私增强技术的场景和方法。本文旨在作为生物识别应用数据保护领域的切入点，面向经验丰富的研究人员和非专家。