论文标题
PEARL：使用WOM编码合理地拒绝闪光翻译层
PEARL: Plausibly Deniable Flash Translation Layer using WOM coding
论文作者
论文摘要
当对手足够强大以胁迫用户揭示加密密钥时，仅加密就不足以用于数据保护。合理的可否认性（PD）机制可以通过使用户仅通过提供同一设备上托管的合理的“封面文本”或“公共数据量”来隐藏敏感数据的存在来解决这一问题。 不幸的是，随着（NAND）闪存作为高性能成本效益的存储介质的越来越多，在存在现实的对手的情况下，PD通常可以在多个时间点访问设备（“ Multi-Snapshot”）。这是因为读/写操作对Flash不会导致对基础设备状态的直观相应更改。由于这种行为主要是专有的事实，问题进一步加剧了问题。例如，在大多数商业上可用的闪光设备中，从上层发出的删除或覆盖操作几乎肯定不会导致实际的立即擦除基础闪光灯。 为了应对这些挑战，我们设计了一类新的写入内存（WOM）代码，以将隐藏的位存储在与其他公共位相同的物理位置。 NAND Flash的固有性质以及向现有页面中未写入的目标单元的多个写作的可能性使这成为可能。 我们设计了Pearl，这是一种通用闪光翻译层（FTL），允许用户合理地将隐藏的数据存储在NAND闪存设备中。我们在广泛使用的模拟器Flashsim上实施并评估了Pearl（Kim等人，2019年）。 Pearl在现实工作负载上表现良好，与非PD基线相对。 Pearl是第一个实现NAND闪存设备可否认可否认性的系统，可保护逼真的多刺激对手。
When adversaries are powerful enough to coerce users to reveal encryption keys, encryption alone becomes insufficient for data protection. Plausible deniability (PD) mechanisms resolve this by enabling users to hide the mere existence of sensitive data, often by providing plausible "cover texts" or "public data volumes" hosted on the same device. Unfortunately, with the increasing prevalence of (NAND) flash as a high-performance cost-effective storage medium, PD becomes even more challenging in the presence of realistic adversaries who can usually access a device at multiple points in time ("multi-snapshot"). This is because read/write operations to flash do not result in intuitive corresponding changes to the underlying device state. The problem is further compounded by the fact that this behavior is mostly proprietary. For example, in a majority of commercially-available flash devices, an issued delete or overwrite operation from the upper layers almost certainly won't result in an actual immediate erase of the underlying flash cells. To address these challenges, we designed a new class of write-once memory (WOM) codes to store hidden bits in the same physical locations as other public bits. This is made possible by the inherent nature of NAND flash and the possibility of issuing multiple writes to target cells that have not previous been written to in existing pages. We designed PEARL, a general-purpose Flash Translation Layer (FTL) that allows users to plausibly deniably store hidden data in NAND flash devices. We implemented and evaluated PEARL on a widely used simulator FlashSim (Kim et al. 2019). PEARL performs well on real-world workloads, comparably to non-PD baselines. PEARL is the first system that achieves strong plausible deniability for NAND flash devices, secure against realistic multi-snapshot adversaries.
