Multi-User File-Sharing Systems Based on LWE

Multi-user file-sharing plays an important role in the cloud storage.It allows different users to share files via the cloud.However,it usually faces many security issues because the cloud is usually public and semi-trusted.To overcome these issues,we propose multi-user file-sharing systems(MFS)in this paper.According to the date sources,we propose two frameworks of MFS based on the framework of proxy re-encryption(PRE),unique source(uni-source)MFS and multi-source MFS.We formalize the security models,which contain ciphertext security,secret key security and master secret security.With the frameworks,we propose two secure and efficient MFS schemes based on LWE,the uni-source MFS UM and the multi-source MFS MM.We prove that UM is secret key and ciphertext security,and MM is secret key,master secret and ciphertext security with the hardness assumptions of LWE and SIS.Furtherly,we prove they have some useful properties,such as non-interactive and anonymous.

不平等与环境两大危机及其应对--世界史分析的方法论意义及历史学家的任务

文章针对人类面临的不平等和环境恶化两大危机,指出现有对不平等的研究局限于经济学的单一解释,缺乏诸如环境和健康等多视域探讨,建议引入世界史方法对1500年以来的全球不平等进行跨学科的大数据分析和考察。文章介绍了应对不平等和环境危机的一个组织(CHIA)和三大项目,讨论了诸项目的内容和目标;阐明对不平等进行世界史分析的理论框架、基本假设及方法论意义;指出在收集、整理及分析数据上面临的七大挑战;分析现有学科知识在应对两大危机上的缺陷,指出历史学家应作的努力。

A One-Time Pad Encryption Scheme Based on Efficient Physical-Layer Secret Key Generation for Intelligent IoT System

The one-time pad(OTP)is an applicationlayer encryption technique to achieve the informationtheoretic security,and the physical-layer secret key generation(SKG)technique is a promising candidate to provide the random keys for OTP.In this paper,we propose a joint SKG and OTP encryption scheme with the aid of a reconfigurable intelligent surface(RIS)to boost secret key rate.To maximize the efficiency of secure communication,we divide the process of secure transmission into two stages:SKG and then encrypted packet transmission.Meanwhile,we design an optimal algorithm for allocating time slots for SKG to maximize SKG efficiency without security risk.Furthermore,we design a key updating protocol based on our SKG scheme for OTP encryption.Simulation results verify that our scheme can generate keys securely and efficiently,and significantly improve the secure communication performance in an intelligent IoT system.

Radio frequency fingerprint identification for Internet of Things:A survey

Radio frequency fingerprint(RFF)identification is a promising technique for identifying Internet of Things(IoT)devices.This paper presents a comprehensive survey on RFF identification,which covers various aspects ranging from related definitions to details of each stage in the identification process,namely signal preprocessing,RFF feature extraction,further processing,and RFF identification.Specifically,three main steps of preprocessing are summarized,including carrier frequency offset estimation,noise elimination,and channel cancellation.Besides,three kinds of RFFs are categorized,comprising I/Q signal-based,parameter-based,and transformation-based features.Meanwhile,feature fusion and feature dimension reduction are elaborated as two main further processing methods.Furthermore,a novel framework is established from the perspective of closed set and open set problems,and the related state-of-the-art methodologies are investigated,including approaches based on traditional machine learning,deep learning,and generative models.Additionally,we highlight the challenges faced by RFF identification and point out future research trends in this field.

Preface: Security and safety in physical layer systems

This special topic mainly focuses on the progress of physical-layer security(PLS)technologies and their potential applications for the future beyond fifth-generation(B5G)and sixth-generation(6G)networks.The tremendous growth in connectivity and the ubiquity of wireless communications have resulted in an unprecedented awareness of the importance of security and privacy.Achieving secure and trusted communications is vital for future intelligent connected applications,especially life-critical vehicle-toeverything(V2X)applications.However,the heterogeneous,dynamic and decentralized architecture of these networks leads to difficulties for cryptographic key management,and distribution.By exploiting the physical characteristics of devices,wireless channels and noise,PLS offers reliable solutions against eavesdropper attacks as complementary approaches to cryptographic techniques.

A High Consistency Wireless Key Generation Scheme for Vehicular Communication Based on Wiener Filter Extrapolation

Secret key generation from wireless channel is an emerging technology for communication network security,which exploits the reciprocity and time variability of wireless channels to generate symmetrical keys between the communication parties.Compared to the existing asymmetric key distribution methods,secret key generation from wireless channel has low complexity and high security,making it especially suitable for distributed networks.In vehicular communications,the reciprocity of wireless channel is degraded due to the movement of vehicular.This paper proposes a high consistency wireless key generation scheme for vehicular communication,especially applied to LTE-V2X(LTE vehicle to everything)systems.A channel reciprocity enhancement method is designed based on Wiener filter extrapolation,which can efficiently reduce the mismatch between the channels at the receiver and significantly reduce key disagreement rate.A real experimental system based on vehicle and universal software radio peripheral(USRP)platform is setup to verify the secret key generation in LTE-V2X systems.The effectiveness of the proposed method is verified in simulations and extensive practical tests.

Secure transmission technology based on direct modulation with random channel characteristics

Aiming at the problem of insufficient security in the existing wireless data trans-mission,a security transmission technology based on direct modulation with random channel characteristics is proposed.The method first estimates channel characteristics using the preamble in the communication frame,and then embeds channel characteristics into the I/Q modulator.After that,the modulated constellation diagram undergoes random hopping of the constellation position compared with the original constellation diagram,thus achieving the effect of secure transmission.Due to the reciprocity of the uplink and downlink channels,channel characteristics estimated by the downlink receiver are almost the same as those esti-mated by the uplink receiver,and the correct plaintext data can be recovered by performing corresponding demodulation with them.Compared with the existing scheme of quantizing channel characteristics and then encrypting data,the method reduces the performance loss caused by quantization.In addition,its bit error rate is lower than that of the quantization method.In general,it has higher security and convenience.

A novel artificial noise aided security scheme to resist blind source separation attacks

In this paper,we discuss the physical layer security from a new angle of view and propose a novel approach to resist some attacks in signal processing perspective.The scenario considered in this paper is that the eavesdropper has the similar channel performance compared to the legitimate receiver.We design the optimal artificial noise(AN)to resist the attacks of the eavesdropper who uses the blind source separation(BSS)technology to reconstruct the secret information.For speech signals,the optimal AN is obtained by minimizing the maximum of the correlation coefficients between the source signal and the received signals at Eve and the correlation coefficients between the source signal and separated results of BSS.For binary phase shift keying(BPSK)signals,we maximize the minimum bit error rates(BERs)of the separated signals and the obtained signals at Eve.Moreover,we consider the AN design from the point of breaking the BSS conditions,and propose a method by changing the correlation coefficient randomly.The simulation results show that the AN we proposed has better performance than that of the white Gaussian AN to resist the BSS attacks for both speech signals and the BPSK signals.

Secure transmission technology based on direct modulation with random channel characteristics

Aiming at the problem of insucient security in the existing wireless data trans-mission,a security transmission technology based on direct modulation with random channel characteristics is proposed.The method rst estimates channel characteristics using the preamble in the communication frame,and then embeds channel characteristics into the I/Q modulator.After that,the modulated constellation diagram undergoes random hopping of the constellation position compared with the original constellation diagram,thus achieving the e ect of secure transmission.Due to the reciprocity of the uplink and downlink channels,channel characteristics estimated by the downlink receiver are almost the same as those esti-mated by the uplink receiver,and the correct plaintext data can be recovered by performing corresponding demodulation with them.Compared with the existing scheme of quantizing channel characteristics and then encrypting data,the method reduces the performance loss caused by quantization.In addition,its bit error rate is lower than that of the quantization method.In general,it has higher security and convenience.

全球史观下的中国社会保险(1949—1978)

现有关于福利国家和社会保险的研究,局限在特定国家的社会、经济和政治背景之下,从而忽视了全球模式在一国社会政策产生演变中的作用。本文通过对福利国家的概念理论,尤其是'社会权利'的简要分析,运用全球史观对中国劳动保险(1949—1978)的兴衰进行了研究。本文将中国20世纪社会保险的发展置于全球社会保险运动的背景之下,即两大社会保险模式(德国资本主义模式和苏联社会主义模式)自19世纪80年代以来在全球的传播。中国在1951年采纳苏联社会保险模式建立了自己的劳动保险制度。然而,苏式劳动保险制度在中国国内政治环境下的实施则是一个失败,大跃进以及'文化大革命'等群众运动最终摧毁了这一劳动保险制度。最后,本文探讨了有关中国社会保险的经验对理解20世纪中国历史的意义。