论文标题
当心丢弃所用SRAM:信息已永久存储
Beware of Discarding Used SRAMs: Information is Stored Permanently
论文作者
论文摘要
数十年来,安全专家长期以来一直是电子行业的重点,重点是硬盘恢复,这是一种非易失性记忆。不幸的是,从学术界,工业或政府中的现有研究都没有考虑从动荡的记忆中恢复数据。根据定义,当数据关闭时会丢失。据我们所知,我们是第一个提出一种从静态随机访问内存中恢复数据的方法。常规的观点是SRAM在关闭时会失去其内容,并且在基于SRAM的计算系统退休时,不需要保护敏感信息,例如固件代码,秘密加密密钥等。不幸的是,综合电路的回收对保护知识产权构成了严重威胁。在本文中,我们提出了一个新颖的概念,可以检索SRAM数据,因为老化会导致带有存储值的烙印的加强状态。我们表明,我们提出的方法可以部分恢复先前使用的SRAM含量。与单个芯片相比,通过合并多个SRAM芯片可以进一步提高恢复数据的准确性。不可能检索某些稳定的SRAM细胞的先前含量,其中衰老会使这些细胞向稳定性转移。由于由于无法控制的过程变化,这些细胞的位置因芯片到芯片而异,同一细胞在任何芯片中都具有较高的不稳定或稳定的机会,这有助于我们恢复内容。最后,多数投票用于结合一组SRAM芯片数据以恢复存储的数据。我们在进行加速衰老之前,使用带有存储的二进制图像数据的商业现成的SRAM介绍了实验结果。我们证明了对SRAM的成功部分检索,这些SRAM的年龄仅为4小时,以85c的速度加速衰老。
Data recovery has long been a focus of the electronics industry for decades by security experts, focusing on hard disk recovery, a type of non-volatile memory. Unfortunately, none of the existing research, neither from academia, industry, or government, have ever considered data recovery from volatile memories. The data is lost when it is powered off, by definition. To the best of our knowledge, we are the first to present an approach to recovering data from a static random access memory. It is conventional wisdom that SRAM loses its contents whenever it turns off, and it is not required to protect sensitive information, e.g., the firmware code, secret encryption keys, etc., when an SRAM-based computing system retires. Unfortunately, the recycling of integrated circuits poses a severe threat to the protection of intellectual properties. In this paper, we present a novel concept to retrieve SRAM data as aging leads to a power-up state with an imprint of the stored values. We show that our proposed approaches can partially recover the previously used SRAM content. The accuracy of the recovered data can be further increased by incorporating multiple SRAM chips compared to a single one. It is impossible to retrieve the prior content of some stable SRAM cells, where aging shifts these cells towards stability. As the locations of these cells vary from chip to chip due to uncontrollable process variation, the same cell has a higher chance of being unstable or stable against aging in any of the chips, which helps us recover the content. Finally, majority voting is used to combine a set of SRAM chips' data to recover the stored data. We present our experimental result using commercial off-the-shelf SRAMs with stored binary image data before performing accelerated aging. We demonstrate the successful partial retrieval on SRAMs that are aged with as little as 4 hours of accelerated aging with 85C.