This dissertation proposes a framework of user-centered security in Natural
Language Processing (NLP), and demonstrates how it can improve the
accessibility of related research. Accordingly, it focuses on two security
domains within NLP with great public interest. First, that of author profiling,
which can be employed to compromise online privacy through invasive inferences.
Without access and detailed insight into these models' predictions, there is no
reasonable heuristic by which Internet users might defend themselves from such
inferences. Secondly, that of cyberbullying detection, which by default
presupposes a centralized implementation; i.e., content moderation across
social platforms. As access to appropriate data is restricted, and the nature
of the task rapidly evolves (both through lexical variation, and cultural
shifts), the effectiveness of its classifiers is greatly diminished and thereby
often misrepresented.
Under the proposed framework, we predominantly investigate the use of
adversarial attacks on language; i.e., changing a given input (generating
adversarial samples) such that a given model does not function as intended.
These attacks form a common thread between our user-centered security problems;
they are highly relevant for privacy-preserving obfuscation methods against
author profiling, and adversarial samples might also prove useful to assess the
influence of lexical variation and augmentation on cyberbullying detection.

本学位论文提出了一种用户中心的自然语言处理（NLP）安全框架，并演示了如何改进相关研究的可访问性。该框架主要研究语言上的对抗攻击，并探讨如何通过语言的对抗样本实现隐私保护，并评估文化变革和词汇增强对网络欺凌检测的影响。