SaTC: CORE: Small: Collaborative: Hardware-assisted Plausibly Deniable System for Mobile Devices

移动计算设备通常使用加密来保护敏感信息。然而，移动设备中使用的传统加密系统无法抵御主动攻击者，这些攻击者可以强制移动设备所有者公开用于解密敏感信息的密钥。对于那些成为国家目标的持不同政见的用户来说，这尤其令人担忧。这方面的一个例子是，一名人权工作者在一个压迫或冲突地区收集不良活动的证据，并将这些证据以加密形式存储在移动设备上，然后被一名官员强迫披露解密密钥。似是而非的加密（PDE）已经被提出来防御这样的对手，他们可以强迫用户泄露加密的敏感内容。然而，现有的技术在基于闪存的移动设备中使用时存在一些问题，例如由于在操作系统级别和闪存转换层处理读/写/擦除操作的方式而导致的弱可否认性，各种类型的侧信道攻击，以及移动设备的计算和功率限制。该项目研究了在主流移动设备上开发高效（低开销）和有效（高可否认性）硬件辅助的PDE方案的独特机会，该方案对多快照对手具有鲁棒性。该项目包括重要的课程开发活动和面向K-12学生的推广活动。该项目通过利用现有的硬件功能，如闪存转换层（FTL）固件和TrustZone，从根本上推进了移动PDE系统，以低开销实现高可否认性。具体来说，该项目开发了一个PDE系统，其功能包括：1)防御使用移动设备上的原始闪存的快照攻击；2)消除损害可否认性的侧信道攻击；3)可扩展到主流移动设备；4)高效提供快速模式切换等实用功能。该项目还为K-12学生和区域网络安全教育合作组织（RCEC）开发了关于PDE和网络安全的新教材，这是密歇根州网络安全方面的一个新的教育合作伙伴关系。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Mobile computing devices typically use encryption to protect sensitive information. However, traditional encryption systems used in mobile devices cannot defend against an active attacker who can force the mobile device owner to disclose the key used for decrypting the sensitive information. This is particularly of concern to dissident users who are targets of nation states. An example of this would be a human rights worker collecting evidence of untoward activities in a region of oppression or conflict and storing the same in an encrypted form on the mobile device, and then being coerced to disclose the decryption key by an official. Plausibly Deniable Encryption (PDE) has been proposed to defend against such adversaries who can coerce users into revealing the encrypted sensitive content. However, existing techniques suffer from several problems when used in flash-memory-based mobile devices, such as weak deniability because of the way read/write/erase operations are handled at the operating systems level and at the flash translation layer, various types of side channel attacks, and computation and power limitations of mobile devices. This project investigates a unique opportunity to develop an efficient (low-overhead) and effective (high-deniability) hardware-assisted PDE scheme on mainstream mobile devices that is robust against a multi snapshot adversary. The project includes significant curriculum development activities and outreach activities to K-12 students. This project fundamentally advances the mobile PDE systems by leveraging existing hardware features such as flash translation layer (FTL) firmware and TrustZone to achieve a high deniability with a low overhead. Specifically, this project develops a PDE system with capabilities to: 1) defend against snapshot attacks using raw flash memory on mobile devices; and 2) eliminate side-channel attacks that compromise deniability; 3) be scalable to deploy on mainstream mobile devices; and 4) efficiently provide usable functions like fast mode switching. This project also develops novel teaching material on PDE and cybersecurity for K-12 students and the Regional Cybersecurity Education Collaboration (RCEC), a new educational partnership on cybersecurity in Michigan.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.