Traffic analysis attacks remain a significant problem for online security. Communication between nodes can be observed by network level attackers as it inherently takes place in the open. Despite online services increasingly using encrypted traffic, the shape of the traffic is not hidden. To prevent traffic analysis, the shape of a system's traffic must be independent of secrets. We investigate adapting the data-oblivious approach the reactive setting and present OblivIO, a secure language for writing reactive programs driven by network events. Our approach pads with dummy messages to hide which program sends are genuinely executed. We use an information-flow type system to provably enforce timing-sensitive noninterference. The type system is extended with potentials to bound the overhead in traffic introduced by our approach. We address challenges that arise from joining data-oblivious and reactive programming and demonstrate the feasibility of our resulting language by developing an interpreter that implements security critical operations as constant-time algorithms.
Network Oblivious Transfer via Noisy Channels: Limits and Capacities
Institute for Communications Technology, Technische Universität Braunschweig（不伦瑞克工业大学通信技术研究所在）；Faculty of Electrical Engineering, K. N. Toosi University of Technology（K. N. 托伊西理工大学电气工程学院）
A Practical Oblivious Map Data Structure with Secure Deletion and History Independence
我们提出了一个新的不经意的RAM，支持可变大小的存储块（vORAM），这是第一个ORAM，允许不同的块大小，没有琐碎的填充。我们还提出了一个新的历史无关的数据结构（HIRB树），可以存储在一个vORAM。总之，这种构造为键/值映射提供了有效且实用的不经意数据结构（ODS），并且与现有ODS映射相比进一步提供了额外的隐私保证：即使在客户端受损时，已删除的数据和旧操作的历史仍然对攻击者隐藏。我们使用Amazon Web Services实现和测量了我们的系统的性能，并且对于一个实际的数据库（最多$2^{18}$条目），单次操作时间小于1秒。这表示与Wang等人（CCS 14）的当前最佳不经意映射数据结构（其既不提供安全删除也不提供历史独立性）相比100倍的加速。
On (Im)possibility of Network Oblivious Transfer via Noisy Channels and Non-Signaling Correlations
Institute for Communications Technology, Technical University of Braunschweig（布伦瑞克工业大学通信技术研究所）；Chair of Theoretical Information Technology, Technical University of Munich（慕尼黑大学理论信息技术讲席）
