Over the last few years, there has been an almost exponential increase in the number of mobile applications that deal with sensitive data, such as applications for e-commerce or health. When dealing with sensitive data, classical authentication solutions based on username-password pairs are not enough, and multi-factor authentication solutions that combine two or more authentication factors of different categories are required instead. Even if several solutions are currently used, their security analyses have been performed informally or semiformally at best, and without a reference model and a precise definition of the multi-factor authentication property. This makes a comparison among the different solutions both complex and potentially misleading. In this article, we first present the design of two reference models for native applications based on the requirements of two real-world use-case scenarios. Common features between them are the use of one-time password approaches and the support of a single sign-on experience. Then, we provide a formal specification of our threat model and the security goals, and discuss the automated security analysis that we performed. Our formal analysis validates the security goals of the two reference models we propose and provides an important building block for the formal analysis of different multi-factor authentication solutions.

中文翻译：

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具有单点登录登录的移动多因素身份验证的形式分析

在过去几年中，处理敏感数据的移动应用程序数量几乎呈指数级增长，例如电子商务或健康应用程序。在处理敏感数据时，基于用户名-密码对的经典认证方案是不够的，而需要结合两个或多个不同类别的认证因素的多因素认证方案。即使当前使用了几种解决方案，它们的安全分析也只是非正式地或半正式地执行，并且没有参考模型和多因素身份验证属性的精确定义。这使得不同解决方案之间的比较既复杂又可能具有误导性。在本文中，我们首先根据两个实际用例场景的要求，为原生应用程序设计两个参考模型。它们之间的共同特征是使用一次性密码方法和支持单点登录体验。然后，我们提供威胁模型和安全目标的正式规范，并讨论我们执行的自动化安全分析。我们的形式分析验证了我们提出的两个参考模型的安全目标，并为不同的多因素身份验证解决方案的形式分析提供了重要的构建块。我们提供了威胁模型和安全目标的正式规范，并讨论了我们执行的自动化安全分析。我们的形式分析验证了我们提出的两个参考模型的安全目标，并为不同的多因素身份验证解决方案的形式分析提供了重要的构建块。我们提供了威胁模型和安全目标的正式规范，并讨论了我们执行的自动化安全分析。我们的形式分析验证了我们提出的两个参考模型的安全目标，并为不同的多因素身份验证解决方案的形式分析提供了重要的构建块。