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的境地。然而，他们显然需要安全地存储数据。通常，秘密数据使用假定不可破解的加密来保护。然而，如果那些处于敌对环境中的人被发现携带加密数据，他们可能会被迫通过胁迫或人身伤害威胁来遵守。调查人员提议，通过隐藏数据，使操作系统甚至不知道它在那里，从而确保数据的安全。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以不可否认的方式可靠地存储数据。通过擦除编码将待隐藏的一组数据块与熵块组合，以产生一组模糊的载波块，然后这些载波块无法与盘上的其他伪随机块区分。然后需要这些块的子集来重建数据。该系统在理论上是信息安全的，不需要知道信息块。该系统将是第一个完全可否认的、安全的和可调的隐写文件系统。所有以前的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，而且调查人员还将建立一个完整的工作系统，能够在密集的法医检查中幸存下来。这将使外地用户能够有一种可靠、安全的方式携带信息，而这些信息的存在不会危及他们的生命。调查人员计划通过可公开获得的来源，如BitBucket或Github，以及在存储和系统研究中心的网页上，在项目期后很长时间内维持该项目。在某种程度上，调查人员打算将该系统包括在Linux源代码树中。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势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.