Implementation and characterization of flash-based hardware security primitives for cryptographic key generation

Hardware security primitives, also known as physical unclonable functions (PUFs), perform innovative roles to extract the randomness unique to specific hardware. This paper proposes a novel hardware security primitive using a commercial off-the-shelf flash memory chip that is an intrinsic part of most commercial Internet of Things (IoT) devices. First, we define a hardware security source model to describe a hardware-based fixed random bit generator for use in security applications, such as cryptographic key generation. Then, we propose a hardware security primitive with flash memory by exploiting the variability of tunneling electrons in the floating gate. In accordance with the requirements for robustness against the environment, timing variations, and random errors, we developed an adaptive extraction algorithm for the flash PUF. Experimental results show that the proposed flash PUF successfully generates a fixed random response, where the uniqueness is 49.1%, steadiness is 3.8%, uniformity is 50.2%, and min-entropy per bit is 0.87. Thus, our approach can be applied to security applications with reliability and satisfy high-entropy requirements, such as cryptographic key generation for IoT devices.     

FPGA-based Physical Unclonable Functions: A comprehensive overview of theory and architectures

Physically Unclonable Functions (PUFs) are a promising technology and have been proposed as central building blocks in many cryptographic protocols and security architectures. Among other uses, PUFs enable chip identifier/authentication, secret key generation/storage, seed for a random number generator and Intellectual Property (IP) protection. Field Programmable Gate Arrays (FPGAs) are re-configurable hardware systems which have emerged as an interesting trade-off between the versatility of standard microprocessors and the efficiency of Application Specific Integrated Circuits (ASICs). In FPGA devices, PUFs may be instantiated directly from FPGA fabric components in order to exploit the propagation delay differences of signals caused by manufacturing process variations. PUF technology can protect the individual FPGA IP cores with less overhead. In this article, we first provide an extensive survey on the current state-of-the-art of FPGA based PUFs. Then, we provide a detailed performance evaluation result for several FPGA based PUF designs and their comparisons. Subsequently, we briefly report on some of the known attacks on FPGA based PUFs and the corresponding countermeasures. Finally, we conclude with a brief overview of the FPGA based PUF application scenarios and future research directions.     

一种基于PUF的物理层安全认证方法

传统无线通信的认证主要依赖于上层加密机制,无法保证系统处理的实时性与物理层的安全性。文章设计了一种基于物理不可克隆函数(Physical Unclonable Function,PUF)进行物理层安全认证的方案,利用硬件固有的激励-响应对(Chalenge-Response Pair,CRP)的唯一性与发送信息的随机性实时生成验证标签,在接收端通过比较接收与生成的标签来识别接收信号与其发射端,为物理层的信息安全提供有效保护。该方法不需要复杂的密码算法,减小了通信过程中的计算量。仿真结果表明,该方法有较高的实用价值。     

基于PUF适用于大规模RFID系统的移动认证协议

针对移动射频识别系统中的安全问题,采用物理不可克隆函数研究适用于大规模RFID系统的移动认证协议。为解决移动RFID认证环境下读写器易遭受假冒攻击的问题,在Vaudenay模型中加入攻击者入侵读写器的能力,并通过服务器对读写器的身份认证来抵御攻击者的假冒攻击;为解决标签的运算能力不足问题和服务器搜索标签耗时长的问题,采用PUF生成会话密钥来减轻标签加密过程中的运算量,服务器通过共享密钥异或运算实现对检索标签和读写器身份标识的快速检索。利用Vaudenay模型理论,分析和证明了研究的协议可实现Destructive等级的隐私保护;仿真结果表明,PMLS协议中服务器的搜索耗时不随标签数目增长而加长,满足大规模移动RFID系统的应用要求。     

基于TrustZone的可信移动终端云服务安全接入方案

可信云架构为云计算用户提供了安全可信的云服务执行环境,保护了用户私有数据的计算与存储安全. 然而在移动云计算高速发展的今天, 仍然没有移动终端接入可信云服务的安全解决方案. 针对上述问题, 提出了一种可信移动终端云服务安全接入方案, 方案充分考虑了移动云计算应用背景, 利用ARM TrustZone硬件隔离技术构建可信移动终端, 保护云服务客户端及安全敏感操作在移动终端的安全执行, 结合物理不可克隆函数技术, 给出了移动终端密钥与敏感数据管理机制. 在此基础之上, 借鉴可信计算技术思想, 设计了云服务安全接入协议, 协议兼容可信云架构, 提供云服务端与移动客户端间的端到端认证. 分析了方案具备的6种安全属性, 给出了基于方案的移动云存储应用实例, 实现了方案的原型系统. 实验结果表明, 可信移动终端TCB较小, 方案具有良好的可扩展性和安全可控性, 整体运行效率较高.     

基于PUFS的不经意传输协议

不经意传输(OT, oblivious transfer）协议是密码学中的一个基本协议。基于物理不可克隆函数（PUF, physical unclonable function）给出物理不可克隆函数系统（PUFS, physical unclonable function system）的概念,并在此基础上提出一个新的不经意传输协议（POT, PUFS based OT）,最后在通用可组合（UC, universal composition）框架内给出POT协议抵抗静态敌手的安全性证明。相比于传统基于公钥加密的OT方案,POT协议不使用任何可计算的假设,而是基于PUFS的安全属性实现,因此在很大程度上减小了计算和通信开销。     

一步法制备聚脲甲醛包覆反应性乙烯基硅油微胶囊

以聚脲甲醛(PUF)为囊壁,乙烯基硅油为囊芯,采用原位聚合"一步法"成功制备出具有自修复功能且粒径均匀的新型PUF包覆乙烯基硅油微胶囊。研究了分散剂/表面活性剂种类及用量、m(囊芯)∶m(囊壁)比例对微胶囊物理性能的影响,并通过扫描电镜(SEM)、金相显微镜、激光粒度分析仪和红外光谱(FT-IR)法等对微胶囊的形貌、粒径大小等进行了研究。结果表明:选用较高浓度的聚乙烯醇(PVA1799)作为分散剂时,有利于微胶囊的形成;当w(PVA1799)=3.00%(相对于体系总质量而言)、m(囊芯)∶m(囊壁)=2.8∶1.0时,在1500r/min条件下,可制备出平均粒径小于20μm且粒径分布较均匀的理想微胶囊。     

基于RRAM PUF的轻量级RFID认证协议

针对当前轻量级的射频识别（RFID）加密方案信息防护手段有限的问题,结合由阻变存储器（RRAM）构成的物理不可克隆函数（PUF）,提出了一种新型的轻量级RFID双向认证协议。利用多级响应加密机制实现阅读器与标签之间的安全认证处理。结合RRAM PUF模型,采用了特殊的纠错处理方法提高PUF响应的可靠性并阻止了信息泄露。此外添加了密钥更新机制和异常攻击标识,抵御了追踪攻击和去同步攻击等威胁。经仿真、分析和对比结果表明,该协议可以有效抵抗多种攻击手段,具有较高的安全性和较低的计算成本。     

Dynamic viscoelasticity of PUF under small strain and prediction of dynamic viscoelasticity in a wide frequency range

The dynamic viscoelasticity of polyurethane fiber (PUF) under small strain was studied with dynamic mechanical analysis and differential scanning calorimetry, and its viscoelasticity was predicted in a wide frequency range. The results revealed that the loss factor (tan δ) was about 0.05 and the phase angle (δ) was 2.86°, very close to the δ of a perfect elastomer in the range from −100°C to −80°C. The master curves superimposed by time-temperature superposition (TTS), the frequency range of the storage modulus master curve spanned 17 orders of magnitude from 10⁻⁷ Hz to 10¹⁰ Hz, and the loss modulus master curve spanned 13 orders of magnitude from 10⁻³ Hz to 10¹⁰ Hz. The apparent activation energy of the soft segment relaxation decreased with increasing temperature in the range from −70 to −26°C. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47070.     

PUF树脂的固化动力学研究

为了使PUF树脂得到有效应用,采用傅立叶红外光谱和DSC热分析技术,对PUF树脂进行固化动力学研究。研究表明,合成的PUF共缩聚树脂,主要是通过羟甲基键进行固化反应;结合Kissingger方程和Ozawa方程及不同物质的量比PUF树脂DSC曲线,显示随着F／（P＋U）物质的量比的提高,固化的表观活化能逐渐减小。得出了不同物质的量比的PUF共聚树脂固化反应动力学模型。