CSR: Small: A Multi-Layered Deniable Steganographic File System

记者、援助工作者和民主倡导者都为了他人的利益而将自己置于危险之中。然而，他们明显需要安全地存储数据。通常，秘密数据是用假定不可破解的加密来保护的。然而，如果在一个充满敌意的环境中，那些人被发现拥有加密的数据，他们可能会被迫通过强迫或身体伤害的威胁来遵守。调查人员建议将数据隐藏起来，这样操作系统甚至都不知道它在那里。因此，所有者可以完全否认数据的存在。隐写文件系统通过使用外部虚拟块设备驱动程序来操作。它利用秘密共享、外部熵源和擦除编码在现有文件系统的未分配空间内可靠地存储数据。通过擦除编码将一组要隐藏的数据块与熵块结合起来，产生一组混淆的载波块，然后与磁盘上的其他伪随机块无法区分。然后需要这些块的一个子集来重建数据。在不知道熵块的情况下，系统理论上是信息安全的。该系统将是第一个完全可否认的、安全的、可调的隐写文件系统。以前的所有尝试都可能获得安全性或性能，但牺牲了可否认性。该项目不仅将突破现代隐写术的界限，而且调查人员将建立一个完整的工作系统，可以通过密集的法医检查。这将使现场用户在不危及其生命的情况下拥有可靠、安全的携带信息的手段。调查人员计划通过Bitbucket或Github等公开资源以及存储和系统研究中心的网页，在项目结束后继续维护该项目。在某种程度上，研究人员打算将该系统包含在Linux源代码树中。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。

Journalists, aid workers, and democracy advocates all put themselves in harm's way for the benefit of others. Yet, there is a glaring need for them to store data securely. Typically, secret data is protected with encryption that is assumed unbreakable. Yet, if those in a hostile environment are caught with encrypted data, they could be forced to comply through coercion or threats of bodily harm. The investigators propose to secure data in plain sight by hiding it so that the operating system does not even know it is there. Therefore, the owner can completely deny the existence of the data.The Steganographic file system operates through the use of an external virtual block device driver. It utilizes secret sharing, external entropy sources, and erasure coding to store data deniably and reliably within the unallocated space of an existing file system. A set of data blocks to be hidden are combined with entropy blocks through erasure coding to produce a set of obfuscated carrier blocks that are then indistinguishable from other pseudorandom blocks on the disk. A subset of these blocks is then required to reconstruct the data. The system is information theoretically secure without knowledge of the entropy blocks.This system will be the first fully deniable, secure, and tunable steganographic file system. All previous attempts might attain security or performance but sacrifice deniability. The project will not only push the boundaries of modern steganography, but the investigators will build a fully working system that can survive intensive forensic examination. This will allow users in the field to have a reliable, secure means of carrying information where the presence of that information does not endanger their lives.The investigators plan to maintain the project well beyond the project period through publicly available sources such as Bitbucket or Github, as well as on the Storage and Systems Research Center's web page. At some point the investigators intend to include the system in the Linux source tree.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.