Abstract

An investigation is performed of individual behavioral characteristics of text input that are based on the keystroke dynamics using a virtual keyboard, and their application in the authentication of mobile device users. Key hold time, time between two consecutive keystrokes, and keystroke pressure are used as features to build a user model. A feature vector of a freely typed text is constructed by a user-adapting algorithm that divides digraphs into groups according to the pressing speed and the grouping of keys according to their functionality. Outliers are sought and corrected on the basis of quartiles with subsequent standardization of values. A fuzzy search for exceptions based on potential functions is used to solve the problem of classification when there are no examples of keystrokes by an attacker in a training sample. The resulting software, which consists of a custom Android system keyboard, is used for data collection and experimental assessment of the quality of the proposed approach to building a user behavioral model, proving its effectiveness. The software is also used to develop a prototype of a user authentication system that employs biometric characteristics of interaction with an onscreen keyboard to protect all applications on a mobile device that uses a standard system keyboard.

中文翻译：

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移动设备用户认证中文本输入的行为模型

摘要

对基于使用虚拟键盘的按键动态的文本输入的各个行为特征进行了调查，并研究了它们在移动设备用户身份验证中的应用。按键保持时间，两次连续击键之间的时间以及击键压力被用作构建用户模型的功能。自由键入文本的特征向量是通过用户自适应算法构造的，该算法会根据按下速度将二字图分为几组，并根据其功能将键分组。在四分位数的基础上寻找并纠正异常值，并随后进行值的标准化。当训练样本中没有攻击者敲击键盘的示例时，可以使用基于潜在函数的模糊搜索来解决分类问题。最终的软件由一个定制的Android系统键盘组成，用于数据收集和实验评估所提出的构建用户行为模型的方法的质量，证明了其有效性。该软件还用于开发用户身份验证系统的原型，该原型利用与屏幕键盘交互作用的生物特征来保护使用标准系统键盘的移动设备上的所有应用程序。